introduction of a literature review

Introductions and Literature Reviews

Author By Troy Mikanovich
Publication date December 16, 2022
Categories: Academic Publication , Research Writing
Categories: academic journal , CARS , introduction , literature review , research , research question

Writing literature reviews is one of the trickiest things you’ll have to do in graduate school. It is even more tricky because a lot of professors will want you to do things that are pedagogically valuable but so tailored to the specific class they are teaching that it can be hard to generalize the lessons you are meant to take away.

This page is meant to be a general overview to the goals and purposes of introductions and literature reviews (or an introduction that contains a literature review–we’ll talk about that), so even if it doesn’t exactly match what you have been asked to do in an assignment, I hope it’ll be helpful.

What is the difference between an introduction and a literature review?

As of writing this, the year is 2022 and words mean nothing. Rather than getting caught up on what these things are in some kind of objective sense, let’s look at what they are supposed to do.

The introduction and the literature review of your paper have the same job. Both are supposed to justify the question(s) you are asking about your topic and to demonstrate to your audience that the thing you are writing about is interesting and of some importance. However, while they have the same job, they do it in two different ways.

An introduction should demonstrate that there is some broader real-world significance to the thing that you are writing about. You can do this by establishing a problem or a puzzle or by giving some background information on your topic to show why it is important. Here’s an example from Brian E. Bride’s “Prevalence of Secondary Traumatic Stress among Social Workers” (2007, link below), where he begins by establishing a problem:

“ In the United States, the lifetime prevalence of exposure to traumatic events ranges from 40 percent to 81 percent, with 60.7 percent of men and 51.2 percent of women having been exposed to one or more traumas and 19.7 percent of men and 11.4 percent of women reporting exposure to three or more such events (Breslau, Davis, Peter-son, & Schultz, 1997; Kessler, Sonnega, Bromet, & Nelson, 1995; Stein, walker, Hazen, & Forde, 1997). Although exposure to traumatic events is high in the general population, it is even higher in subpopulations to whom social workers are likely to provide services…

Although not exhaustive of the populations with whom social workers practice, these examples illustrate that social workers face a high rate of professional contact with traumatized people. Social workers are increasingly being called on to assist survivors of childhood abuse, domestic violence, violent crime, disasters, and war and terrorism. It has become increasingly apparent that the psychological effects of traumatic events extend beyond those directly affected.”

So, Bride (2007) starts with a broad problem (lots of people with exposure to traumatic events) and narrows it to a more specific problem (social workers who work with those people are exposed to secondary trauma as they assist them) .

A literature review should demonstrate that there is some academic significance to the thing you are writing about. You can do this by establishing a scholarly problem (i.e. a “research gap”) and by demonstrating that the state of the existing scholarship on your topic needs to develop in a particular way.

As Bride (2007) transitions to talking about the scholarship on the topic of social workers and secondary trauma, he establishes what scholarship has done and identifies what it has not done .

“Figley (1999) defined secondary traumatic stress as “the natural, consequent behaviors and emotions resulting from knowledge about a traumatizing event experienced by a significant other. It is the stress resulting from helping or wanting to help a traumatized or suffering person” (p. 10). Chrestman (1999) noted that secondary traumatization includes symptoms parallel to those observed in people di-rectly exposed to trauma such as intrusive imagery related to clients’ traumatic disclosures (Courtois, 1988; Danieli, 1988; Herman, 1992; McCann & Pearlman, 1990); avoidant responses (Courtois; Haley, 1974); and physiological arousal (Figley, 1995; McCann & Pearlman, 1990). Thus, STS is a syndrome of symptoms identical to those of PTSD, the characteristic symptoms of which are intrusion, avoidance, and arousal (Figley, 1999)…

Collectively, these studies have provided empirical evidence that individuals who provide services to traumatized populations are at risk of experiencing symptoms of traumatic stress (Bride). However, the extant literature fails to document the prevalence of individual STS symptoms and the extent to which diagnostic criteria for PTSD are met as a result of work with traumatized populations.”

Taken together, Bride (2007) justifies its existence–the research that the author has undertaken in order to read the article that you are now reading–like this:

Broad real world background: Lots of people are suffering from traumatic stress.

Narrowed real world background: People who have suffered traumatic experiences often work with social workers.

Real world problem: Many social workers may through their work suffer from secondary exposure to traumatic experiences.

Broad academic background: There has been a lot of research on secondary traumatic stress

Narrowed academic background: Particularly, this research has shown that social workers are at risk of experiencing symptoms of secondary traumatic stress.

Academic problem/gap : We don’t know how prevalent individual symptoms of secondary traumatic stress are.

Introductions, then, give you space to explain why you are writing about the thing you are writing about, and literature reviews are where you explain what prior scholarship has said about the topic and what the consequences of that prior scholarship are. In an introduction you are writing about the topic; in a literature review you are writing about people writing about the topic.

Diagram showing how in the introduction you are writing about a topic and in a literature review you are writing about a scholarly conversation

So does a literature review need to be a separate section from an introduction? Or is a literature review part of an introduction?

It depends on your field, tbh. And on the expectations of the assignment/journal/outlet that you are writing for.

For instance, in the above example (Bride, 2007) the literature review is a part of the introduction. Here’s that paper and some other examples of other places where this is the case. Notice that they do not differentiate between an introductory section and a distinct “Literature Review” as they outline their topic/questions before describing their methodology:

Bride, B. E. (2007) Prevalence of secondary traumatic stress among social workers. Social Work, 52 (1), 63-70. https://doi.org/10.1093/sw/52.1.63

Wei, X., Teng, X., Bai, J., & Ren, F. (2022). Intergenerational transmission of depression during adolescence: The mediating roles of hostile attribution bias, empathetic concern, and social self-concept. The Journal of Psychology, 157 (1), 13-31. https://doi.org/10.1080/00223980.2022.2134276

Stephens, R., Dowber, H., Barrie, A., Sannida, A., & Atkins, K. 2022) Effect of swearing on strength: Disinhibition as a potential mediator. Quarterly Journal of Experimental Psychology . Advance online publication. https://doi.org/10.1177/17470218221082657

However, plenty of other articles have distinct “Literature Review” sections separate from their introductions. The first two examples name it as such, while the third organizes its literature review with thematic sub-sections:

Schraedley, M.K., & Dougherty, D.S. (2021). Creating and disrupting othering during policymaking in a polarized context. Journal of Communication, 72 (1), 111-140. https://doi.org/10.1093/joc/jqab042

Gil de Zúñiga, H., Cheng, Z., & González-González, P. (2022). Effects of the news finds me perception on algorithmic news attitudes and social media political homophily. Journal of Communication, 72 (5), 578-591. https://doi.org/10.1093/joc/jqac025

Brandão, T., Brites, R., Hipólito, J., & Nunes O. (2022) Attachment orientations and family functioning: The mediating role of emotion regulation. The Journal of Psychology , 157 (1), 1-12. https://doi.org/10.1080/00223980.2022.2128284

Whether you separate your literature review into its own distinct section is mostly a function of what you’ve been asked to do (if you are writing for a class) or what the conventions and constraints are of your field.

Literature Reviews

Overview of Literature Reviews and Systematic Reviews
How to Get Started and Developing a Research Question
Finding and Evaluating Sources
Citations This link opens in a new window
Synthesizing Sources
Writing the Literature Review
Systematic Reviews This link opens in a new window
Suggested Readings
Elements of a Literature Review
Introduction
Reference List

All literature reviews contain the following elements:

See the tabs to right for further explanation of each of these elements.

The introduction to a literature review should include the following:

Define the topic to provide context for the review
Identify trends in previous publications
Give your reasoning for reviewing the literature (Why is it necessary? What is your point of view?)
Explain the criteria that was used to conduct the search
Indicate how the review is organized

The body of the literature review will discuss each source. Find patterns and ways to tie the main points together. This can be organized thematically, chronologically, or methodologically.

Thematic-organized around a topic or issue

Chronological-organized according to when the articles were published or according to when trends took place

Methodological-organized by the methods used by the researchers

The conclusion should summarize the literature review. Discuss any implications drawn from the literature and what further research is needed.

A reference list at the end of a literature review is essential. Citing all sources gives credit to the authors of the literature, allows others to find the literature for evaluation or their own research, and helps to avoid plagiarism. For more information on creating a reference list, see our Citation Styles guide.

Adding Content & Organizing the Review

The literature review is about both content and form. In terms of content, keep in mind that your literature review is intended to:

Set up a theoretical framework for your own research
Show a clear understanding of the key concepts/ideas/studies/models related to your topic
Demonstrate knowledge about the history of your research area and any related controversies
Illustrate that you are able to evaluate and synthesize the work of others
Clarify significant definitions and terminology
Develop a space in your discipline for your research

Some questions to ask yourself when you begin to write your first draft include:

How will my literature review be organized: Chronologically, thematically, conceptually, methodologically or a combination?
What section headings will I be using?
How do the various studies relate to each other?
What contributions do they make to the field?
What are the limitations of a study/where are the gaps in the research?
And finally but most importantly, how does my own research fit into what has already been done?

Some questions to ask after the first draft:

Is there a logical flow from section to section, paragraph to paragraph, sentence to sentence?
Does the content proceed from topic to topic?
Does your conclusion match your introduction?
Were you consistent in documenting and using the correct citation style?

Attribution

The content of this page was developed from Chapter 8, "Writing a Literature Review" in:

Frederiksen, L., & Phelps, S. F. (2017). Literature reviews for education and nursing graduate students. Rebus Community. https://open.umn.edu/opentextbooks/textbooks/literature-reviews-for-education-and-nursing-graduate-students

<< Previous: Synthesizing Sources
Next: Systematic Reviews >>
Last Updated: Nov 30, 2023 1:07 PM
URL: https://libguides.chapman.edu/literature_reviews

Literature Reviews

Introduction.

Tutorials and resources
Step 1: Literature search
Step 2: Analysis, synthesis, critique
Step 3: Writing the review

If you need any assistance, please contact the library staff at the Georgia Tech Library Help website .

This guide will answer some common questions about literature reviews and point you to useful resources to learn more. This guide is organized in the following sections:

Tutorials and resources for further exploration
Literature search
Analysis, synthesis, critique
Writing the review

What is a literature review?

What does that mean? The literature review establishes the fact that you have familiarized yourself with the particular area(s) or discipline(s) in which you are conducting research. A literature review will summarize the existing scholarly literature on your chosen topic, establish relationships between different research projects of the past, show where there are gaps in past research , and show how the past published work relates to your own work.

Why is a literature review important?

The literature review is a vital part of the argument the author makes in support of a thesis. The literature review offers brief descriptions , summaries , and critical evaluations of each work, and does so in the form of a well-organized essay. The goal is to summarize , synthesize , and critique arguments and ideas of others, and point to gaps in the current literature.

The literature review shows where your own research work is situated in the current research landscape. The literature review sets the stage for showing how your own work advances and expands upon the work done before , fills in knowledge gaps, or maybe - in some cases - disproves or debunks what was previously thought to be true. The literature review, therefore, is an essential part of a well-researched thesis, so it's important to do it right.

Acknowledgments

The following resources were invaluable in the creation of this resource guide.

University of Michigan Library
RMIT University Library
Case Western Reserve University Kelvin Smith Library
Next: Tutorials and resources >>
Last Updated: Apr 2, 2024 11:21 AM
URL: https://libguides.library.gatech.edu/litreview

University Library

Write a literature review.

Examples and Further Information

1. Introduction

Not to be confused with a book review, a literature review surveys scholarly articles, books and other sources (e.g. dissertations, conference proceedings) relevant to a particular issue, area of research, or theory, providing a description, summary, and critical evaluation of each work. The purpose is to offer an overview of significant literature published on a topic.

2. Components

Similar to primary research, development of the literature review requires four stages:

Problem formulation—which topic or field is being examined and what are its component issues?
Literature search—finding materials relevant to the subject being explored
Data evaluation—determining which literature makes a significant contribution to the understanding of the topic
Analysis and interpretation—discussing the findings and conclusions of pertinent literature

Literature reviews should comprise the following elements:

An overview of the subject, issue or theory under consideration, along with the objectives of the literature review
Division of works under review into categories (e.g. those in support of a particular position, those against, and those offering alternative theses entirely)
Explanation of how each work is similar to and how it varies from the others
Conclusions as to which pieces are best considered in their argument, are most convincing of their opinions, and make the greatest contribution to the understanding and development of their area of research

In assessing each piece, consideration should be given to:

Provenance—What are the author's credentials? Are the author's arguments supported by evidence (e.g. primary historical material, case studies, narratives, statistics, recent scientific findings)?
Objectivity—Is the author's perspective even-handed or prejudicial? Is contrary data considered or is certain pertinent information ignored to prove the author's point?
Persuasiveness—Which of the author's theses are most/least convincing?
Value—Are the author's arguments and conclusions convincing? Does the work ultimately contribute in any significant way to an understanding of the subject?

3. Definition and Use/Purpose

A literature review may constitute an essential chapter of a thesis or dissertation, or may be a self-contained review of writings on a subject. In either case, its purpose is to:

Place each work in the context of its contribution to the understanding of the subject under review
Describe the relationship of each work to the others under consideration
Identify new ways to interpret, and shed light on any gaps in, previous research
Resolve conflicts amongst seemingly contradictory previous studies
Identify areas of prior scholarship to prevent duplication of effort
Point the way forward for further research
Place one's original work (in the case of theses or dissertations) in the context of existing literature

The literature review itself, however, does not present new primary scholarship.

Next: Examples and Further Information >>

Creative Commons Attribution 3.0 License except where otherwise noted.

Land Acknowledgement

The land on which we gather is the unceded territory of the Awaswas-speaking Uypi Tribe. The Amah Mutsun Tribal Band, comprised of the descendants of indigenous people taken to missions Santa Cruz and San Juan Bautista during Spanish colonization of the Central Coast, is today working hard to restore traditional stewardship practices on these lands and heal from historical trauma.

The land acknowledgement used at UC Santa Cruz was developed in partnership with the Amah Mutsun Tribal Band Chairman and the Amah Mutsun Relearning Program at the UCSC Arboretum .

The Literature Review: 1. Introduction

1. Introduction
2. Why Do a Literature Review?
3. Methods for Searching the Literature
4. Analysing the Literature
5. Organizing the Literature Review

6. Writing the Review

1. About This Guide

This guide provides an introduction to the literature review process:

1. Introduction 1. About This Guide | 2. What is the Literature? | 3. What is a Literature Review? | 4. What a Literature Review is Not! | 5. Literature Reviews: An Overview for Graduate Students

2. Why Do a Literature Review? 1. Reasons for Doing a Literature Review | 2. Purposes of a Literature Review | 3. Components of a Literature Review

4. Analysing the Literature 1. Recording the Literature | 2. The Evolving Literature Review | 3. Questions to Ask

5. Organizing the Review 1. Organizing Principles | 2. Structure of the Literature Review | 3. Tips on Structure | 4. Selected Online Resources | 5. A Final Checklist

1. Writing the Literature Review Part 1: Step-by-Step Tutorial for Graduate Students | 2. Writing the Literature Review Part 2: Step-by-Step Tutorial for Graduate Students | 3. Tips for Effective Literature Reviews | 4. Literature Review Samples | 5. Resources @ UWISA Libraries

2. What is the "Literature"?

The works you consult in order to identify the ideas and knowledge that have been established on your topic:

Journal articles are the most common sources of materials for literature reviews. They provide:

concise and up-to-date information
some guarantee of the quality of the work they publish

Books are usually less up-to-date than journal articles. They are:

useful for providing overall summaries of the state of knowledge in an area
a starting point for finding more detailed information sources

Conference proceedings may contain research not yet published in journals.

Reports of government and international agencies

Theses and dissertations can be valuable sources of original research

Newspapers and magazines may inlcude news stories on research that you can follow up to find more detail

Web pages/documents on the Internet

3. What is a Literature Review?

Definitions

" The analysis, critical evaluation and synthesis of existing knowledge relevant to your research problem, thesis or the issue you are aiming to say something about " (Hart, 2018, p. 3 & 4)

"A literature review uses as its database reports of primary or original scholarlship and does not report new primary scholarship itself.... Second, a literature review seeks to describe, summarize, evaluate, clarify and/or interrogate the content of primary reports." (Cooper, 1998, p. 7)

"A literature review is a written document that presents a logically argued case founded on a comprehensive understanding of the current state of knowledge about a topic of study. This case establishes a convincing thesis to answer a study's question." (Machi & McEvoy, 2016, p. 5)

Writing a Literature Review A useful guide with respect to the where, when, why, what and how of the literature review.

4. What a Literature Review is Not!

It is not an annotated bibliography!

An annotated bibliography "is a list of citations to books, articles, and documents. Each citation is followed by a brief (usually about 150 words) descriptive and evaluative paragraph, the annotation. The purpose of the annotation is to inform the reader of the relevance, accuracy, and quality of the sources cited." Definition from Cornell University Library, available at http://guides.library.cornell.edu/annotatedbibliography

Major Differences

Literature Review

Written in essay style and organized around a central idea or thesis
A single source may be referred to numerous times depending on its importance in the field or its relationship to other sources

Annotated Bibliography

An alphabetical list of sources accompanied by summaries
A single source appears just once

5. Literature Reviews: An Overview for Graduate Students - NCSU Video

Acknowledgement

Research guide updated and maintained by petronetta pierre - robertson indexer/documentalist.

Sincere thanks to Jennifer Warburton of the University of Melbourne for permission to draw on some of the content of her Guide .

Next: 2. Why Do a Literature Review? >>
Last Updated: Feb 8, 2022 5:25 PM
URL: https://libguides.uwi.edu/litreviewsoe

University Libraries
Research Guides
Subject Guides

What is a literature review?

Getting Started

Introduction

Definition and use/purpose, four stages, questions to ask.

Finding the Literature
Organization
Connect with Your Librarian
More Information

Acknowledgements

This page is based on Write a Literature Review from UC Santa Cruz.

Helpful links

Literature review assignments Helpful breakdown of common elements and their purposes in lit reviews from Auckland University of Technology
Literature review scoring rubric From, Boote, D. N., & Beile, P. (2005). Scholars before researchers: On the centrality of the dissertation literature review in research preparation. Educational Researcher, 34(6), 3-15. doi:10.3102/0013189x034006003 (p.8)
Writing a Short Literature Review An example of a literature review in stages, from annotated bibliography to lit review by William Ashton, Ph.D., York College, CUNY.

A literature review may constitute an essential chapter of a thesis or dissertation, or may be a self-contained review of writings on a subject. In either case, its purpose is to:

Place each work in the context of its contribution to the understanding of the subject under review
Describe the relationship of each work to the others under consideration
Identify new ways to interpret, and shed light on any gaps in, previous research
Resolve conflicts amongst seemingly contradictory previous studies
Identify areas of prior scholarship to prevent duplication of effort
Point the way forward for further research
Place one's original work (in the case of theses or dissertations) in the context of existing literature

The literature review itself, however, does not present new primary scholarship.

Similar to primary research, development of the literature review often follows four stages:

Problem formulation—which topic or field is being examined and what are its component issues?
Literature search—finding materials relevant to the subject being explored
Data evaluation—determining which literature makes a significant contribution to the understanding of the topic
Analysis and interpretation—discussing the findings and conclusions of pertinent literature

Literature reviews can comprise the following elements:

An overview of the subject, issue or theory under consideration, along with the objectives of the literature review
Division of works under review into categories (e.g. those in support of a particular position, those against, and those offering alternative theses entirely)
Explanation of how each work is similar to and how it varies from the others
Conclusions as to which pieces are best considered in their argument, are most convincing of their opinions, and make the greatest contribution to the understanding and development of their area of research

In assessing each resource (e.g., article, book chapter) you collect as part of your research, consider:

Provenance—What are the author's credentials? Are the author's arguments supported by evidence (e.g. primary historical material, case studies, narratives, statistics, recent scientific findings)?
Objectivity—Is the author's perspective even-handed or prejudicial? Is contrary data considered or is certain pertinent information ignored to prove the author's point?
Persuasiveness—Which of the author's theses are most/least convincing?
Value—Are the author's arguments and conclusions convincing? Does the work ultimately contribute in any significant way to an understanding of the subject?
What is already known about the area of study?
What are the characteristics of the key concepts or the main factors or variables?
What are the relationships between these key concepts, factors, or variables?
What are the existing theories?
What are the inconsistencies or other shortcomings in our knowledge and understanding?
Why study (further) the research problem?
What contribution can your study be expected to make?
Next: Finding the Literature >>
Last Updated: Aug 17, 2023 9:45 AM
URL: https://libguides.unm.edu/litreview

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Conducting a literature review: why do a literature review, why do a literature review.

How To Find "The Literature"
Found it -- Now What?

Besides the obvious reason for students -- because it is assigned! -- a literature review helps you explore the research that has come before you, to see how your research question has (or has not) already been addressed.

You identify:

core research in the field
experts in the subject area
methodology you may want to use (or avoid)
gaps in knowledge -- or where your research would fit in

It Also Helps You:

Publish and share your findings
Justify requests for grants and other funding
Identify best practices to inform practice
Set wider context for a program evaluation
Compile information to support community organizing

Great brief overview, from NCSU

Want To Know More?

Next: How To Find "The Literature" >>
Last Updated: Apr 25, 2024 1:10 PM
URL: https://guides.lib.berkeley.edu/litreview

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The Literature Review

What is a Literature Review?
Plan Your Literature Review
Identify a Research Gap
Define Your Research Question
Search the Literature
Analyze Your Research Results
Manage Research Results
Write the Literature Review

What is a Literature Review? What is its purpose?

The purpose of a literature review is to offer a comprehensive review of scholarly literature on a specific topic along with an evaluation of the strengths and weaknesses of authors' arguments . In other words, you are summarizing research available on a certain topic and then drawing conclusions about researchers' findings. To make gathering research easier, be sure to start with a narrow/specific topic and then widen your topic if necessary.

A thorough literature review provides an accurate description of current knowledge on a topic and identifies areas for future research. Are there gaps or areas that require further study and exploration? What opportunities are there for further research? What is missing from my collection of resources? Are more resources needed?

It is important to note that conclusions described in the literature you gather may contradict each other completely or in part. Recognize that knowledge creation is collective and cumulative. Current research is built upon past research findings and discoveries. Research may bring previously accepted conclusions into question. A literature review presents current knowledge on a topic and may point out various academic arguments within the discipline.

What a Literature Review is not

A literature review is not an annotated bibliography . An annotated bibliography provides a brief summary, analysis, and reflection of resources included in the bibliography. Often it is not a systematic review of existing research on a specific subject. That said, creating an annotated bibliography throughout your research process may be helpful in managing the resources discovered through your research.
A literature review is not a research paper . A research paper explores a topic and uses resources discovered through the research process to support a position on the topic. In other words, research papers present one side of an issue. A literature review explores all sides of the research topic and evaluates all positions and conclusions achieved through the scientific research process even though some conclusions may conflict partially or completely.

From the Online Library

SAGE Research Methods is a web-based research methods tool that covers quantitative, qualitative and mixed methods. Researchers can explore methods and concepts to help design research projects, understand a particular method or identify a new method, and write up research. Sage Research Methods focuses on methodology rather than disciplines, and is of potential use to researchers from the social sciences, health sciences and other research areas.

Sage Research Methods Project Planner - Reviewing the Literature View the resources and videos for a step-by-step guide to performing a literature review.

The Literature Review: Step by Step

Follow this step-by-step process by using the related tabs in this Guide.

Define your Research question
Analyze the material you’ve found
Manage the results of your research
Write your Review

Getting Started

Consider the following questions as you develop your research topic, conduct your research, and begin evaluating the resources discovered in the research process:

What is known about the subject?
Are there any gaps in the knowledge of the subject?
Have areas of further study been identified by other researchers that you may want to consider?
Who are the significant research personalities in this area?
Is there consensus about the topic?
What aspects have generated significant debate on the topic?
What methods or problems were identified by others studying in the field and how might they impact your research?
What is the most productive methodology for your research based on the literature you have reviewed?
What is the current status of research in this area?
What sources of information or data were identified that might be useful to you?
How detailed? Will it be a review of ALL relevant material or will the scope be limited to more recent material, e.g., the last five years.
Are you focusing on methodological approaches; on theoretical issues; on qualitative or quantitative research?

What is Academic Literature?

What is the difference between popular and scholarly literature?

To better understand the differences between popular and scholarly articles, comparing characteristics and purpose of the publications where these articles appear is helpful.

Database Search Tips

Boolean Operators
Keywords vs. Subjects
Creating a Search String
Library databases are collections of resources that are searchable, including full-text articles, books, and encyclopedias.
Searching library databases is different than searching Google. Best results are achieved when using Keywords linked with Boolean Operators .
Applying Limiters such as full-text, publication date, resource type, language, geographic location, and subject help to refine search results.
Utilizing Phrases or Fields , in addition to an awareness of Stop Words , can focus your search and retrieve more useful results.
Have questions? Ask a Librarian

Boolean Operators connect keywords or concepts logically to retrieve relevant articles, books, and other resources. There are three Boolean Operators:

Using AND

Narrows search results
Connects two or more keywords/concepts
All keywords/concepts connected with "and" must be in an article or resource to appear in the search results list

Venn diagram of the AND connector

Example: The result list will include resources that include both keywords -- "distracted driving" and "texting" -- in the same article or resource, represented in the shaded area where the circles intersect (area shaded in purple).

Broadens search results ("OR means more!")
Connects two or more synonyms or related keywords/concepts
Resources appearing in the results list will include any of the terms connected with the OR connector

Venn diagram of the OR connector

Example: The result list will include resources that include the keyword "texting" OR the keyword "cell phone" (entire area shaded in blue); either is acceptable.

Excludes keywords or concepts from the search
Narrows results by removing resources that contain the keyword or term connected with the NOT connector
Use sparingly

Venn diagram of the NOT connector

Example: The result list will include all resources that include the term "car" (green area) but will exclude any resource that includes the term "motorcycle" (purple area) even though the term car may be present in the resource.

A library database searches for keywords throughout the entire resource record including the full-text of the resource, subject headings, tags, bibliographic information, etc.

Natural language words or short phrases that describe a concept or idea
Can retrieve too few or irrelevant results due to full-text searching (What words would an author use to write about this topic?)
Provide flexibility in a search
Must consider synonyms or related terms to improve search results
TIP: Build a Keyword List

Example: The keyword list above was developed to find resources that discuss how texting while driving results in accidents. Notice that there are synonyms (texting and "text messaging"), related terms ("cell phones" and texting), and spelling variations ("cell phone" and cellphone). Using keywords when searching full text requires consideration of various words that express an idea or concept.

Subject Headings
Predetermined "controlled vocabulary" database editors apply to resources to describe topical coverage of content
Can retrieve more precise search results because every article assigned that subject heading will be retrieved.
Provide less flexibility in a search
Can be combined with a keyword search to focus search results.
TIP: Consult database subject heading list or subject headings assigned to relevant resources

Example 1: In EBSCO's Academic Search Complete, clicking on the "Subject Terms" tab provides access to the entire subject heading list used in the database. It also allows a search for specific subject terms.

Example 2: A subject term can be incorporated into a keyword search by clicking on the down arrow next to "Select a Field" and selecting "Subject Terms" from the dropdown list. Also, notice how subject headings are listed below the resource title, providing another strategy for discovering subject headings used in the database.

When a search term is more than one word, enclose the phrase in quotation marks to retrieve more precise and accurate results. Using quotation marks around a term will search it as a "chunk," searching for those particular words together in that order within the text of a resource.

"cell phone"

"distracted driving"

"car accident"

TIP: In some databases, neglecting to enclose phrases in quotation marks will insert the AND Boolean connector between each word resulting in unintended search results.

Truncation provides an option to search for a root of a keyword in order to retrieve resources that include variations of that word. This feature can be used to broaden search results, although some results may not be relevant. To truncate a keyword, type an asterisk (*) following the root of the word.

For example:

Library databases provide a variety of tools to limit and refine search results. Limiters provide the ability to limit search results to resources having specified characteristics including:

Resource type
Publication date
Geographic location

In both the EBSCO and ProQuest databases, the limiting tools are located in the left panel of the results page.

EBSCO ProQuest

The short video below provides a demonstration of how to use limiters to refine a list of search results.

Each resource in a library database is stored in a record. In addition to the full-text of the resources, searchable Fields are attached that typically include:

Journal title
Date of Publication

Incorporating Fields into your search can assist in focusing and refining search results by limiting the results to those resources that include specific information in a particular field.

In both EBSCO and ProQuest databases, selecting the Advanced Search option will allow Fields to be included in a search.

For example, in the Advanced Search option in EBSCO's Academic Search Complete database, clicking on the down arrow next to "Select a Field" provides a list of fields that can be searched within that database. Select the field and enter the information in the text box to the left to use this feature.

Stop words are short, commonly used words--articles, prepositions, and pronouns-- that are automatically dropped from a search. Typical stop words include:

In library databases, a stop word will not be searched even if it is included in a phrase enclosed in quotation marks. In some instances, a word will be substituted for the stop word to allow for the other words in the phrase to be searched in proximity to one another within the text of the resource.

For example, if you searched company of America, your result list will include these variatons:

company in America
company of America
company for America

Creating an Search String

This short video demonstrates how to create a search string -- keywords connected with Boolean operators -- to use in a library database search to retrieve relevant resources for any research assignment.

Database Search Menu Template Use this search menu template to plan a database search.
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Last Updated: May 7, 2024 2:33 PM
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Literature Reviews - An Introduction: Definition

How do I recognize a Literature Review?
How do I find a Literature Review?
How do I write a Literature Review?

For Library Updates

Literature review: definition and example.

A Literature Review is "a systematic, explicit, and reproducible method for identifying, evaluating, and synthesizing the existing body of completed and recorded work produced by researchers, scholars, and practitioners."

- From Conducting Research Literature Reviews: From Internet to Paper , by Arlene Fink, 2nd ed. Sage Publications: Thousand Oaks, 2005.

Subject Guide

Next: How do I recognize a Literature Review? >>
Last Updated: Dec 11, 2019 3:02 PM
URL: https://suffolk.libguides.com/LitReview

Introduction

Welcome to Writing in the Social Sciences!
Author Biographies
Acknowledgments
UNIT 1. WRITING TOOLS
1. Writing in the Social Sciences
2. Writing Tools
3. Writing Processes
4. Grammar & Mechanics
UNIT 2. ACADEMIC AUDIENCES
7. Writing for Academic Audiences
8. Finding & Evaluating Sources
9. Discussing & Citing Sources
10. Defining Literature Reviews
11. Planning Literature Reviews
12. Writing Literature Reviews
13. Crafting Proposals
UNIT 3. GENERAL AUDIENCES
14. Writing for General Audiences
15. Applying for Jobs & Graduate Schools
16. Creating Public Texts
17. Presenting
Translations

Writing Literature Reviews

Choose a sign-in option.

Tools and Settings

Questions and Tasks

Citation and Embed Code

Learning Outcomes

writing an introduction, body paragraphs, a discussion/conclusion, abstract, and other elements
drafting and getting feedback
revising your literature review

Note: Because this chapter involves the steps for writing your Literature Review, the discussion questions in each section will be more involved than in other chapters, so give yourself extra time. But never fear! They will all lead to writing a better paper.

12.1 Draft and Synthesize

First, I want you to watch this 10-minute video because it both reviews what we talked about in the last chapter and provides great ways to get started on the actual writing of your paper. Here are some highlights to pay attention to:

questions to ask as you take or review your notes that will guide your writing

suggestions for how to organize your notes. (Or actually, I should spell it "organise" with an "s" since the video comes from Australia.)

ways to add interpretation to what you say about your sources

language to use to comment on the studies you're summarizing and synthesizing

examples of literature review synthesis

Video Review

What three strategies or elements from the video do you plan to incorporate into your own Literature Review?

Start Drafting

Now it's time to start drafting your paper. Follow the structure from your outline and start filling in the missing parts. Get out your notes and remind yourself of the sources you plan to talk about. You don't have to write your paper from beginning to end in order—you can go to the parts that feel the easiest and start there. Here are some places you can start:

Bullet-Point Draft

Writing your Bullet Points should be as fast as this Bullet Train. Photo by Fikri Rasyid on Unsplash

I often have my students start with a Bullet-Point draft that takes the ideas they've been outlining and fills them in with more details but only in bullet-point form. The beauty of bullet points is that they keep you from getting caught up in the language and style and allow you to focus simply on your main points. You can smooth out the sentences and transitions later, but for now, just get your ideas on the page.

Write the Introduction

Another way to get started is to just write the Introduction. You already have a thesis statement that can go at the end, so now you can start introducing your topic and its importance, setting up your Literature Review. See below for more specific help with Introductions.

Write a Body Paragraph

Or a third place to start is to jump into writing a body paragraph that synthesizes your sources—the way you did in that synthesis activity earlier. Take your notes and choose one set to talk about in paragraph form.

Don't think too hard about getting things perfect when you're drafting—that's what revision is for. Just focus on getting started and filling in some of the missing pieces. If you get stuck, do some brainstorming activities to get your creative juices flowing. Once you have something written, I suggest seeking feedback to make sure you're going in the right direction. In fact, I recommend getting as much feedback as possible along the way.

Start Writing

Now it's your turn to choose somewhere to start writing—choose either a bullet-point draft, the introduction, a body paragraph or something else. Then write the equivalent of at least one paragraph.

How to Write Each Section

Once you know what your main points will be, you're ready to introduce your ideas. As in any paper, you can't just jump right into your thesis statement and points; you need to set the stage first. Here are the elements of a good introduction to a literature review:

A good introduction

introduces the topic and indicates its importance (impact on individuals)
gives a context for the research question
defines key terms, concepts, and/or theories
explains what search methods were used and how many and what types of sources were reviewed (this is sometimes optional)
suggests the organization of the rest of the paper

Remember in some style guides like the APA Manual , you don't need to title your Introduction "Introduction"—you simply center the title of your paper at the top of your page (bolded and in title capitalization format) and then jump right into your first paragraph.

Tip: You don't always know where you're going when you start a paper, so just get a good draft of an introduction down. Then when you finish writing a first draft of your paper, read your conclusion and consider using some of it in your introduction instead. I often tell my students that conclusions make good introductions because you finally know exactly where you went in your paper. Either way, you'll want to revisit your introduction once your paper's done so you can adjust it to better match where your paper went.

Get a start on your introduction by writing an opening sentence that introduces your topic and/or indicates its importance. Then you can use that to jump start the rest of your introduction.

The body of your paper is where you can develop your points and use your newfound synthesis skills. Remember the synthesis activity with the videos you did in the last chapter? As you create a draft, you can start composing paragraphs using your awesome notes just like you practiced with those videos. Try to incorporate several sources into each paragraph to be sure that you're synthesizing and not just summarizing or listing without making connections. Your color-coded notes can help you be sure that each paragraph contains multiple sources.

In the body of your paper, you should

synthesize previous studies to inform the reader of the state of research

“identify relations, contradictions, gaps, and inconsistencies in the literature” ( APA Manual , p. 8)

group your points into major headings and subheadings (You choose the arrangement based on what you’ve found: similar concepts or theories, similar methods, chronological development, controversies, etc.)

support all points with sound reasoning or evidence drawn from sources and in which all borrowed information is documented

summarize sources most of the time, paraphrase sometimes, and use quotations very sparingly—only when specific wording is poignant or can’t be said in any other way.

One way to talk about your sources is known as the CEC Method: Claim-Evidence-Commentary.

Claim + Evidence + Commentary

Just like any paragraph, you should start with a Topic sentence that acts as a mini-Thesis statement or a general claim about your topic. Then you need to give evidence to support that claim. In a literature review, your evidence comes in the form of studies that have been done—all those brilliant notes you've been taking. This is where you can synthesize your sources and show that they are related under the umbrella of a topic. However, just listing or summarizing sources does not make the connection between them and your topic sentence clear. This is where commentary comes in. Your job is also to comment on and interpret the significance of your "evidence" so your audience can understand the connections between them. In synthesis, your language is the key.

In the next chapter, we'll talk more about how to do this, especially how to incorporate metacommentary into your paragraphs.

Add Metacommentary

Metacommentary is the key to synthesis. metacommentary (aka metadiscourse) is a type of commentary that guides your reader and helps them interpret the sources and evidence you're presenting. Think of it as really powerful transitions. First, let's remind ourselves what transitions are. Transition words act like signposts—they guide your reader through your points. They can also glue your ideas together so they feel more cohesive. Beware that transitions can definitely be overdone, but I'd say most students in general could use more transitions in their papers rather than fewer.

Here's an awesome list of transition words (also linked in the frame below) that are grouped by category from the famous Purdue OWL (Online Writing Lab—scroll down to see the list). You can also download a great handout from the University of Maryland here .

I always suggest that my students keep a categorized transition list like this handy as they write so that when they know they want to connect ideas in a certain way (e.g. to show contrast), you can easily find a good list of options (e.g. in contrast, conversely, etc.). Not only will transitions help your ideas feel more connected, they will also smooth out your writing style like butter.

You might think you can just stop at transition words, but metacommentary is much more than just sprinkling some "therefores" and "howevers" throughout your paper—metacommentary actually takes your synthesis to the next level. Remember the Claim-Evidence-Commentary pattern I've mentioned? The commentary part of that sandwich is where you should focus right now. What do you comment on? You can either highlight why a source is important or connect it with other sources. This is your chance to point out the answers to the four questions you looked for in your note-taking:

What do researchers agree and disagree about?

How are researchers narrowing or changing their focus to create new information?

What are each study’s limitations and strengths?

What’s the next step in research—what should be studied in the future? (The research gap)

You can think of metacommentary as a sandwich with your name on it. If my student's name were Alisa, here's what an "Alisa sandwich" would look like:

ALISA—SOURCE—ALISA

First, Alisa starts with a claim about what's happening in the field or about a particular subsection or focus of the field. This could serve as a topic sentence for a paragraph, for example.

Second, she sets up the source with guiding language like transitions and references to her past points or sources.

Third, she talks about the source itself and summarizes pertinent information.

Lastly, Alisa comments on the source and/or connects it to her main point or to next source.

This metacommentary is a lot like the interpretation mentioned in the video at the beginning of this chapter. This type of "sandwich" can occur several times in a paragraph as you synthesize your sources. Here's a sample paragraph from Chris, a Public Health student, (check this) who wrote a paper called "The Causes of a Behavioral Pandemic: Screen-time Addiction and Consequent Depression Among Adolescents." I've bolded the metacommentary Chris had added to guide his readers and to connect his points together.

Even though there have been far fewer studies on adolescents than adults , adolescent studies have consistently shown that those who are more physically active experience less depressive and associated symptoms, as well as a greater overall state of well-being (Kremer 2014). These studies have also shown that low levels of vigorous exercise in youth can independently cause depressive symptoms. One longitudinal study revealed that over 30% of children who participate in high levels of screen-time use experience moderate to high levels of depressive symptoms (Kremer 2014). Additionally, another study of children in the United States demonstrated that those who participated on a sports team were less likely to exceed recommended screen-time limits established by the US Department of Health. This study also demonstrated that as the number of total physical activity sessions increased among youth, both during free time and at organized events, children were less likely to exceed recommended screen-time limits (Carlson 2010). In this study, children who were more physically active consistently showed lower rates of depression and other emotional disorders. Therefore, evidence across multiple studies suggests that participating in screen-time activity may not be the direct cause of depressive symptoms, but rather the sedentary lifestyle and lack physical activity it causes among youth. With this recent evidence, experts are beginning to search for ways to replace screen-time participation of adolescents with physical activities.

If You Get Stuck

Literature reviews can be hard. If you get stuck, I have a little trick I tell my students. For your first draft, try starting every sentence with "Researchers . . ." I know this seems formulaic, but if you can keep your focus on what particular researchers did or what they agree or disagree on, you'll avoid the most common pitfalls of literature reviews: sounding like a typical argumentative research paper. If your focus is always on what researchers are doing or what they've found, then at the very least you'll stay in the realm of the literature review genre. Later you can go back through and change up your sentence structure, but I've found that this is an easy way for students to get through a first draft.

A Quick Word on Verb Tense

Verb Tenses to Use in Literature Reviews

Discussion/Conclusion

Your last section will either be called discussion or conclusion (or will possibly not have a heading depending on your teacher's preferences or the style guide you're following). In an effective Discussion (aka Conclusion) section you should

do more than sum up what you have said (though you should do that as well)

explain where there are gaps and limitations in the previous research done

indicate recommendations for future research based on those gaps

At the end of this section,

restate your position (thesis statement)

show the implications of your findings

You must also include a list of your References (also known as a Bibliography or Works Cited page depending on the documentation style) showing all the sources you referred to in your paper. Your references page must be in alphabetical order and formatted according to your chosen style guide (see Chapter 9: Talking About Sources ).

Other Elements

Your teacher might require you to include these other elements in your Literature Review paper. Be sure to follow the format from your style guide .

I've waited until now to talk about titles because it's wise to wait until you have a good draft before you choose a title. Why? Because you often don't know exactly where your paper will go until you've written it out. Your title is your readers' first entry into your paper, so you want it to be interesting and also reflect what's inside. Your title should also include as much information as possible while remaining appropriately short and sweet. For example, the APA Manual recommends not using extraneous words but sticking to the main point of your paper. My student Justin's title follows this model:

Implications of Chinese Involvement on Africa's Economy

He basically summarizes his main point in one succinct statement—the ultimate summary. APA would be proud.

360px-Someones_Mullet_from_their_Family_Photos_(39958323871).jpg

However, depending on your sub-field in the Social Sciences, many scholars like to do what I call a "reverse mullet." As you might know, the rad '80s mullet haircut that's short on top and long in the back has been described as

The Mullet: Business in the front, party in the back

A mullet starts with the serious and ends with the fun. But academic titles often do the reverse: they have an interesting introductory phrase, then a colon, and then the standard, more serious title. That's why I call them the

The Reverse Mullet: Party in the front, Business in back

A reverse mullet title gets the reader's attention before adding the serious explanation. For example, one of my students named Katelyn wrote her Literature Review on how much high school students' perception of their teachers was influenced by their teachers' apparel. Her title included a Reverse Mullet structure:

Keeping it Class-y: How Formality of Teacher Apparel Affects Student Perceptions of the Teacher in the Classroom

Your Name (centered)
Your Teacher's Name (centered on the next line)
A Page Number (in the top right corner that's continued throughout the paper)
Optional: the Name of the School or Department
Optional: the Name/Number of Your Course (e.g., English 315)
Optional: the Date

You should save writing your abstract until after you've completed your paper because it's a summary of the main points of your paper. You can try writing a preliminary abstract now as a type of outline, but you run the risk of finding out that once you're done with your paper, you actually went in some different directions. My advice is to hold off and wait to write the abstract until the end. You can create a page after the title page where your abstract will go, but to emphasize that you should write this last, we'll wait to cover the details of writing an an abstract until the next section.

If you have tables or figures ( or formulas or other data) that are too big to be added inside the text of your paper, you can put them at the end. If you only have one Appendix , you can call it just that. But if you have more than one, call them Appendix A, Appendix B, etc. and refer to them as such in the text of your paper.

Tables and Figures

One more element that could be helpful to your paper is to include tables and/or figures. You're probably familiar with Tables (you know, the boxes with lots of horizontal and vertical cells). A Figure is any type of image, graph, or chart besides a table. You can use tables or figures from your sources as long as you cite them properly. You can also create your own table or figure either from existing data or to explain a concept. See Chapter 6: Design for the details of how to create, use, or format tables and figures. Just remember to check your style guide; for example, in APA Format, you need to title and number your tables and figures separately.

I hope you feel like you have a better sense of the structure for your own Literature Review paper. In the next chapter, we'll talk about how to draft and revise your paper.

12.2 Write an Abstract

4k-wallpaper-abstract-abstract-expressionism-abstract-painting-acrylic-paint-art-1563849-pxhere.com.jpg

Not that kind of abstract! As great as abstract art is, what you need now is the abstract of your paper. (Note: some teacher's won't require an abstract, so you can skip this section in that case.) Why do you think we've saved the abstract for last even though it's the first thing your audience will read (after your title)? You guessed it: it's because the abstract is a summary of everything you've talked about in your paper, so if you haven't written your paper yet, it's pretty hard to summarize it.

A lot of students think that the abstract is a preview of your paper that simply invites the reader to learn more. But that's not the purpose of the abstract, that's the purpose of the Introduction . If your paper were a movie, your abstract would not be the movie trailer. A movie trailer is an invitation to see more without giving away too much; that's the point of your Introduction . Instead, your abstract would be the movie plot synopsis. It would have a big SPOILER ALERT sign in front of it because in it you want to give away all the punchlines from your paper. In fact, the more you include your most important points or findings, the better. Because readers might only ever read your abstract, you want the most important information there. Then just like you did in your own database searching, they will decide based on the abstract whether they should open your paper and read more details. Your job is to make sure they have the best information to do that.

An abstract has a few main parts that mirror the parts of your paper but in miniature. First, in 1-2 sentences, you should introduce the topic, its importance, and the problem or question you tried to answer. Then you should succinctly explain your methods (database searching) and the scope of your project. The last and largest part should consist of your main findings such as the main areas of inquiry where researchers are congregating. You should include the major strengths and limitations (gaps) you found in your review. Finally, you should explain any implications of your study and suggest where future research should go. See? A miniature paper. It should be so miniature, that the APA Manual says an abstract should not exceed 250 words. At the end, you can also list a few Keywords to make it easy to search for your paper on databases.

To solidify your understanding of how to write an abstract, watch this 3-minute video from the University of Melbourne that takes you through a good example. Try not to get distracted by their awesome Australian accents.

Now if you would like more details, you can refer to this explanation.

12.3 The Real Last Step: Revise (and Revise and Revise)

The best writers revise (and revise and revise). Think back to Chapter 3: Writing Processes and the section on Revision. You need to think like your audience, which means you have to get out of your own head and think mindfully. One way to do this is to revise with purpose or in other words, with specific goals in mind.

You can't revise without a decent draft, so don't blow off the first draft deadline. The better your first draft, the better your paper will be in the end because you'll have enough time to really look at your paper. Actually re-look at your paper, or in other words, re-vise. Get it? Re-vision?

So how can you get out of your own head? Two ways: people and levels. The first way to get a fresh perspective is audience-oriented revision: peer review, teacher conferences, writing center appointments, and other outside feedback from real, live people.

Get Feedback!

When you find out how other people react to your paper, it will give you invaluable perspective into what's working and what's not. This is feedback and is extremely valuable. Your teacher should help you do these kinds of peer reviews and revisions in class.

Feedback can also come from anyone—friends, teachers, relatives, Writing Center tutors, roommates—just be sure to choose someone you trust who also knows about good writing and won't hesitate to tell you where you can improve. I don't know your grandma, but if she's the type of grandma who will tell you your paper is great no matter what's in it because you're just so nice, then run away! Okay, don't really run away from your grandma—she's probably very loving and supportive. Give her a hug instead. However, don't give your paper to your grandma to critique in that case. My grandma is actually a fantastic writer and wouldn't be afraid to tell me where I can improve. Do give your paper to someone like my grandma.

Here's a tip: Most universities have a Writing Center where you can take your paper to a Writing Tutor for help and feedback for free. Do it! It's free! And they can even meet with you online.

We're lucky at BYU that we even have our very own Social Science-specific Writing Center: the FHSS Writing Lab . They know Literature Reviews well and can help you with any stage of the writing process from selecting a topic to citing sources to synthesis. If you have more general writing questions (or if you need an appointment after 5pm), you can also go to the main BYU Research & Writing Center . They also offer online appointments. If you're not on our campus, look up your school's writing center.

As an undergrad, my husband didn't start out with the best writing skills, so he used to take his papers to the BYU Writing Center over and over and over. I think they made the rule that you can only go once a day because of him. And guess what? It helped! His grades went up! That was his secret to success that I'm passing on to you. Your teacher doesn't have time to personally meet with each student over and over and over, but the Writing Tutors are literally paid to do just that. Well, maybe keep your visits to only one per day, but you get what I mean. Take advantage! Make an appointment right now! Did I mention that it's free?

If you need more motivation to just do it, watch this "motivational" video by Shia Le Boeuf.

Revise by Levels

The second way to improve your paper is to go through a layered revision process focusing on global and then local issues. As you re-see your paper, take my advice and tackle Global Revision before you focus on Local Revision . What do I mean by that? Let me tell you a quick story.

A Revision Story Involving Cats

When my family and I were moving to our town, we looked at a lot of houses online. We fell in love with a beautiful old house that had been totally renovated but was selling at a shockingly low price. When we finally visited the house with our realtor, we discovered why it had been on the market for so long: it smelled like cat pee. Like really, really smelled. It turns out the house had been occupied by what many people would call a "crazy cat lady"—an older woman who lived with at least 50 cats. Then tragically, a fire completely destroyed the house (I'm pretty sure the woman and her cats survived).

The home owner used $400,000 of insurance money to beautifully restore the house. They rebuilt the intricate wooden staircase, restored the stately crown molding, installed lush carpet, and added upgrades to a gorgeous kitchen. The only problem was that they did their restoration in the wrong order—they took care of the local issues of paint color and carpet thickness while ignoring the more global issue of the smell. Eventually, they had to rip up all their work in the basement in order to treat the floor with a special enzyme that combated cat urine. If they'd just treated the cat smell first, then they could have saved themselves thousands of dollars, hours of work, and could have sold their house for a much higher price.

The Moral of the Story

What does all this have to do with revision? You've got it—treat the g lobal issues first! Get rid of the cat pee! Don't worry about local issues like flowery language or sentences that connect perfectly to each other if you're just going to have to completely renovate that section later. Work on the global issues like ideas, logical order, and evidence first and wait until those are intact before focusing on the details. Put another way, whole-paper and paragraph-level revisions should come before sentence-level and word-level changes.

As a final gift, fantastic BYU Family Science professor Julie Haupt offers the following path for doing four purposeful revisions—two global revisions and two local revisions. If you really want to improve your literature review, follow these steps.

GLOBAL REVISION—The Forest

Level 1: Structural Review (Global)

Purpose: The structural review examines the document as a whole to see if all requirements are met and the document’s organization is sound.

Meet Assignment Requirements. Ask yourself if your paper meets all the requirements of the assignment? Look at your structure and make sure you have all necessary sections such as the following:

Introduction (with Thesis Statement and/or Organizing Statement)

Body with Headings

Conclusion/Discussion

Include a Thesis and an Organizing Statement. Does the current version of the thesis statement match the tone, scope, and organization of the body text? Does an organizing statement after the thesis introduce the major topics and the order they will appear in the body (e.g., “In this review, I will first discuss . . . then . . . and finally . . .)

Use Headings. Is the body text subdivided in a logical way with evidence-based information located in appropriate sections? Are the major sections roughly symmetrical (in terms of length)? Are the headings brief, yet descriptive? If subheadings are used, does the major section contain at least two? Are all levels of headings separated by text?

Level 2 (Global): Paragraph/Logic Review

Purpose: The Paragraph/Logic Review is designed to review each paragraph for cohesion and compliance to the CEC (Claim-Evidence-Commentary) format.

Sequence Paragraphs Effectively. When reading only the first sentence of each paragraph, does the logical pattern of the paper emerge? Do the claims made in these topic sentences coordinate well with the thesis of the paper?

LOCAL REVISION—The Tree

Level 3 (Local): APA Formatting Review

Purpose: The APA Formatting Review is designed to make sure all APA conventions are explicitly followed to help the paper reflect a high level of professionalism.

Check Document Formatting. Do the title page, abstract, body text, and reference page appear in the correct page formatting as required? (Use the APA Manual if you have questions.)

Examine the Reference List Closely. Are all references in the reference list ordered alphabetically? Is the reference list double spaced entirely (with no extra gaps between paragraphs)? Are all references (e.g., journal articles, internet resources, or books) listed in the correct format? Is every reference on the reference list cited at least once in the body and does each in-text citation have a corresponding reference in the reference list?

Make a Final Check of the In-Text Citations. Is all information properly cited with an in-text citation when needed? Do all in-text citations include the year next to the author(s)? When more than one citation is listed within parentheses are they separated by semi-colons and ordered alphabetically by first author’s last name? If included in parentheses, do studies with multiple authors use ampersands ("&" rather than the word "and") before listing the last author?

Use “et al.” Correctly. If a study has three or more authors, do you include only the first author’s last name + et al. + publication year in in-text citations? Do you include all authors up to 20 in the References page? For any publications with 21 or more authors, do you include the first 19 authors' name, then insert an ellipsis ( . . . ), and then the last author's name?

Level 4 (Local): Finishing Review

Purpose: The Finishing Review is an opportunity to look closely at sentence construction, language, hedging (qualifying statements), and grammar/punctuation.

Review Phrasing with a Read-Aloud Session. Read your paper aloud. Since having to read a sentence twice to get its meaning or “tripping over” phrasing can be an indication of awkward construction, are all sentences easily read aloud? Are any sentences so long that they have become difficult to comprehend, but could be split without changing the meaning?

Use Non-Biased, Non-Absolute Language. Do all references to people comply with the “people first” designation and avoid inappropriate uses of terms for various groups? Are the findings and summary statements in the review properly “ hedged ”?

Check Punctuation and Grammar. Are all commas, semicolons, colons, hyphens, and other punctuation used correctly throughout the document (including the reference page)? Are common grammar mistakes, such as parallelism, subject-verb agreement, incorrect misuse of pronouns, and other grammatical issues corrected?

I know Literature Reviews can be daunting, but I hope that after reading this chapter you feel better prepared to tackle this bodacious writing assignment. As you practice writing, you'll find that it'll get easier and easier until it's as intuitive as riding a hoverboard.

*Bonus Video

If you're still confused or would like more guidance on writing a literature review, here is an optional 25-minute video that thoroughly goes through the entire process of writing a literature review. As an extra bonus, it's made by Michael Paye from the University of Dublin who has an awesome Irish accent. Enjoy!

Brigham Young University

Cristie Cowles Charles teaches writing and literature courses at Brigham Young University in Provo, Utah. She enjoys sparking a love for writing in her students--or at least a love for having had written (it's always worth it in the end, right?). She thinks pumpkin pie counts as a vegetable, is married to a super hot mechanical engineering and neuroscience professor (yes, they exist), and adores her five magnificent children.

This content is provided to you freely by EdTech Books.

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The Guide to Thematic Analysis

Abductive Thematic Analysis
Collaborative Thematic Analysis
Deductive Thematic Analysis
How to Do Thematic Analysis
Inductive Thematic Analysis
Reflexive Thematic Analysis
Advantages of Thematic Analysis
Thematic Analysis for Case Studies
Thematic Coding
Disadvantages of Thematic Analysis
Thematic Analysis in Educational Research
Thematic Analysis Examples
Thematic Analysis for Focus Groups
Thematic Analysis vs. Grounded Theory
What is Thematic Analysis?
Increasing Rigor in Thematic Analysis
Thematic Analysis for Interviews
Introduction

What is a thematic literature review?

Advantages of a thematic literature review, structuring and writing a thematic literature review.

Thematic Analysis in Mixed Methods Approach
Thematic Analysis in Observations
Peer Review in Thematic Analysis
How to Present Thematic Analysis Results
Thematic Analysis in Psychology
Thematic Analysis of Secondary Data
Thematic Analysis in Social Work
Thematic Analysis Software
Thematic Analysis in Surveys
Thematic Analysis in UX Research
Thematic vs. Content Analysis
Thematic Analysis vs. Discourse Analysis
Thematic Analysis vs. Framework Analysis
Thematic Analysis vs. Narrative Analysis
Thematic Analysis vs. Phenomenology

Thematic Analysis Literature Review

A thematic literature review serves as a critical tool for synthesizing research findings within a specific subject area. By categorizing existing literature into themes, this method offers a structured approach to identify and analyze patterns and trends across studies. The primary goal is to provide a clear and concise overview that aids scholars and practitioners in understanding the key discussions and developments within a field. Unlike traditional literature reviews , which may adopt a chronological approach or focus on individual studies, a thematic literature review emphasizes the aggregation of findings through key themes and thematic connections. This introduction sets the stage for a detailed examination of what constitutes a thematic literature review, its benefits, and guidance on effectively structuring and writing one.

A thematic literature review methodically organizes and examines a body of literature by identifying, analyzing, and reporting themes found within texts such as journal articles, conference proceedings, dissertations, and other forms of academic writing. While a particular journal article may offer some specific insight, a synthesis of knowledge through a literature review can provide a comprehensive overview of theories across relevant sources in a particular field.

Unlike other review types that might organize literature chronologically or by methodology , a thematic review focuses on recurring themes or patterns across a collection of works. This approach enables researchers to draw together previous research to synthesize findings from different research contexts and methodologies, highlighting the overarching trends and insights within a field.

At its core, a thematic approach to a literature review research project involves several key steps. Initially, it requires the comprehensive collection of relevant literature that aligns with the review's research question or objectives. Following this, the process entails a meticulous analysis of the texts to identify common themes that emerge across the studies. These themes are not pre-defined but are discovered through a careful reading and synthesis of the literature.

The thematic analysis process is iterative, often involving the refinement of themes as the review progresses. It allows for the integration of a broad range of literature, facilitating a multidimensional understanding of the research topic. By organizing literature thematically, the review illuminates how various studies contribute to each theme, providing insights into the depth and breadth of research in the area.

A thematic literature review thus serves as a foundational element in research, offering a nuanced and comprehensive perspective on a topic. It not only aids in identifying gaps in the existing literature but also guides future research directions by underscoring areas that warrant further investigation. Ultimately, a thematic literature review empowers researchers to construct a coherent narrative that weaves together disparate studies into a unified analysis.

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Conducting a literature review thematically provides a comprehensive and nuanced synthesis of research findings, distinguishing it from other types of literature reviews. Its structured approach not only facilitates a deeper understanding of the subject area but also enhances the clarity and relevance of the review. Here are three significant advantages of employing a thematic analysis in literature reviews.

Enhanced understanding of the research field

Thematic literature reviews allow for a detailed exploration of the research landscape, presenting themes that capture the essence of the subject area. By identifying and analyzing these themes, reviewers can construct a narrative that reflects the complexity and multifaceted nature of the field.

This process aids in uncovering underlying patterns and relationships, offering a more profound and insightful examination of the literature. As a result, readers gain an enriched understanding of the key concepts, debates, and evolutionary trajectories within the research area.

Identification of research gaps and trends

One of the pivotal benefits of a thematic literature review is its ability to highlight gaps in the existing body of research. By systematically organizing the literature into themes, reviewers can pinpoint areas that are under-explored or warrant further investigation.

Additionally, this method can reveal emerging trends and shifts in research focus, guiding scholars toward promising areas for future study. The thematic structure thus serves as a roadmap, directing researchers toward uncharted territories and new research questions .

Facilitates comparative analysis and integration of findings

A thematic literature review excels in synthesizing findings from diverse studies, enabling a coherent and integrated overview. By concentrating on themes rather than individual studies, the review can draw comparisons and contrasts across different research contexts and methodologies . This comparative analysis enriches the review, offering a panoramic view of the field that acknowledges both consensus and divergence among researchers.

Moreover, the thematic framework supports the integration of findings, presenting a unified and comprehensive portrayal of the research area. Such integration is invaluable for scholars seeking to navigate the extensive body of literature and extract pertinent insights relevant to their own research questions or objectives.

The process of structuring and writing a thematic literature review is pivotal in presenting research in a clear, coherent, and impactful manner. This review type necessitates a methodical approach to not only unearth and categorize key themes but also to articulate them in a manner that is both accessible and informative to the reader. The following sections outline essential stages in the thematic analysis process for literature reviews , offering a structured pathway from initial planning to the final presentation of findings.

Identifying and categorizing themes

The initial phase in a thematic literature review is the identification of themes within the collected body of literature. This involves a detailed examination of texts to discern patterns, concepts, and ideas that recur across the research landscape. Effective identification hinges on a thorough and nuanced reading of the literature, where the reviewer actively engages with the content to extract and note significant thematic elements. Once identified, these themes must be meticulously categorized, often requiring the reviewer to discern between overarching themes and more nuanced sub-themes, ensuring a logical and hierarchical organization of the review content.

Analyzing and synthesizing themes

After categorizing the themes, the next step involves a deeper analysis and synthesis of the identified themes. This stage is critical for understanding the relationships between themes and for interpreting the broader implications of the thematic findings. Analysis may reveal how themes evolve over time, differ across methodologies or contexts, or converge to highlight predominant trends in the research area. Synthesis involves integrating insights from various studies to construct a comprehensive narrative that encapsulates the thematic essence of the literature, offering new interpretations or revealing gaps in existing research.

Presenting and discussing findings

The final stage of the thematic literature review is the discussion of the thematic findings in a research paper or presentation. This entails not only a descriptive account of identified themes but also a critical examination of their significance within the research field. Each theme should be discussed in detail, elucidating its relevance, the extent of research support, and its implications for future studies. The review should culminate in a coherent and compelling narrative that not only summarizes the key thematic findings but also situates them within the broader research context, offering valuable insights and directions for future inquiry.

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Introduction and Literature Review

First Online: 14 November 2020

Cite this chapter

Ibrahim Moukhtar 5 ,
Adel Z. El Dein 5 ,
Adel A. Elbaset 6 , 7 &
Yasunori Mitani 8

Part of the book series: Power Systems ((POWSYS))

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1 Citations

As the world’s supply of fossil fuels shrinks, there is a great need for clean and affordable renewable energy sources (RES) in order to meet growing energy demands. Furthermore, the conventional plants based on fossil fuel have serious environmental and financial problems, and therefore, the dependency of the distribution networks on the RES such as solar power systems for generating electrical power is significantly promoted. In the past few decades, solar energy systems have been received great attention as an important type of RES. Nowadays, solar energy sources constitute appropriate commercial options for small and large power plants. The two mainstream categories of solar energy systems utilized for this purpose are concentrated solar power (CSP) and photovoltaic (PV). This chapter presents a brief introduction about the role, important need, and advantages of renewable energies for today and the future, especially solar energy such as PV and CSP systems. In addition, it introduces a survey for all types of CSP technologies. As well as, it presents a literature review for the LCOE and cost reduction of CSP and PV systems, CSP modeling, and the application of ANN technologies in various SF systems. Further, it presents the problem definition, objectives, and outlines of this thesis.

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Electrical and Electronic Engineering, Kyushu Art Institute of Technology, Tobata-ku, Fukuoka, Japan

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Moukhtar, I., El Dein, A.Z., Elbaset, A.A., Mitani, Y. (2021). Introduction and Literature Review. In: Solar Energy. Power Systems. Springer, Cham. https://doi.org/10.1007/978-3-030-61307-5_1

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Exploring Social Media as an Information Source in IL Instruction

Kathia Salomé Ibacache Oliva, Elizabeth Novosel, and Stacy Gilbert *

According to a 2021 Pew Research report, over 80 percent of 18- to 29-year-olds use social media. Studies also show that higher education students use social media in both academic and everyday life. However, there is minimal research about how, or whether, librarians utilize social media in their library instruction as a source of information for students’ academic work. We examined 162 responses to a survey sent to an uncounted number of librarians in higher education, asking them about their teaching practices regarding social media to enable us to answer the following research questions: (1) How are teaching librarians using social media as an information source in their instruction?; (2) What are the benefits teaching librarians perceive regarding the use of social media in instruction?; (3) What are the challenges teaching librarians perceive regarding the use of social media in instruction? The survey results showed that most librarians surveyed are not utilizing social media as an information source in their library instruction. Although our results cannot be generalized, our study sheds light on how librarians incorporate social media in information literacy (IL) instruction, the tension between scholarly literature and voices not considered authoritative, and librarians’ perceptions of benefits and challenges to incorporating social media in library sessions.

Introduction

In today’s world, information moves fast, circulated by digital technologies such as social media. The first social media platforms, as we know them today, appeared in the late 1990s; 1 this led to dozens of sites captivating millions of people by the early 2000s, propelled by the emergence of Web 2.0 technologies. Today, social media is very much present in the lives of higher education students. According to a 2021 Pew Research report, over 80 percent of 18- to 29-year-olds use social media. 2 With people and organizations worldwide sharing information of varied authority, there is both potential—and a need—for librarians to teach students how to use social media critically to discover and access information for academic assignments. Addressing a gap in the literature, this paper explores whether and how teaching librarians utilize social media as a pedagogical tool in their library instruction to help learners find sources of information for their academic work. Additionally, our study reports on librarians’ perceptions of the benefits and challenges of using social media in library sessions.

Inspired by a faculty member’s request for a library session covering hashtags and social media skills to help students find reliable information sources, this exploration also responds to changes we have observed in higher education attitudes toward including underrepresented voices in addition to traditional scholarly perspectives in the academic narrative. First, we will summarize scholarly literature regarding college students’ use of social media as an information source, social media in higher education classrooms, and social media within library instruction. Second, we will present data gathered through a survey. Third, we will discuss the data in relation to our research questions and address possible benefits and challenges of using social media in library instruction.

What is Social Media in this Study?

This paper follows Andreas M. Kaplan and Michael Haenlein’s definition of social media : “a group of Internet-based applications that build on the ideological and technological foundations of Web 2.0, and that allow the creation and exchange of User Generated Content.” 3 We favored this definition because it emphasizes the notion of user-generated content. The eleven social media platforms utilized in this study were taken from a Pew Research Center article on social media use in 2021. The platforms are: YouTube, Facebook, Instagram, Pinterest, LinkedIn, Snapchat, Twitter, WhatsApp, TikTok, Reddit, and Nextdoor. 4

How is “Information Source” Defined in this Study?

In the context of social media, we understand an information source to be a primary or secondary source used for academic research or for assignments in a higher education setting. For example, students may access a report from a governmental office’s social media account, or may find a scholarly article posted by an author or an academically affiliated account.

Literature Review

There is abundant literature about the use of social media in different academic fields. 5 However, research about teaching librarians’ utilization of social media as a source of information within the context of IL instruction is scarce. 6 In a 2011 paper examining social media in the research workflow, David Nicholas expressed concern about librarians’ disconnect with social media in the academic setting because scholars were using social media to share their research. 7 His study surveyed 2,414 academics in 215 countries and found that researchers strongly agree that social media enhances their academic work “through the greater visibility it affords them.” 8 Nonetheless, a decade later, academic librarians still appear to be unlikely to introduce social media in IL instruction beyond minimal coverage of evaluation, shared content, online collaboration, and observation of informal scholarly interaction. This literature review considers studies addressing how students use social media as an information source for academic work, as well as social media applications in the higher education classroom.

Students’ Use of Social Media as an Information Source

Within the last decade, a few studies have noted that students use social media as a source of both background information and news for their academic work. 9 Referring to student use of social media, both for information seeking and academic purposes, librarians Kyung-Sun Kim, Yuqi He, and Sei-Chin Joanna Sin noted in 2013 that, while undergraduate students utilized media sharing sites such as Social Q&A and Wikis, graduate students preferred blogs. 10 These authors observed that students’ majors also determined the social media platforms they utilized. 11

Similarly, in 2014, Kim, Sin, and Eun Young Yoo-Lee found that students use some social media platforms as information sources, including Wikipedia and social networking sites. 12 Recently, a 2021 literature review examining students’ preferences on reading formats and the use of social media information sources for academic and non-academic purposes noted that college students use social media for “class assignments and projects.” 13 This review added that students use YouTube as a supplement for textbooks, blogs to follow topics of interest, and LinkedIn to check the authority of authors. 14

Interestingly, a 2021 paper—in which Kim, Sin, and Yoo-Lee compared two undergraduate cohorts’ (2013 and 2019) use of social media as an information source for academic and everyday purposes—found data that contradicts that of the Pew Research Center. Kim et al. found that the 2019 cohort utilized social media as an information source less frequently than the 2013 cohort did, suggesting a decline in use, 15 while a Pew Research Center study showed the opposite, reporting increased use of social media in 18- to 29-year-olds in 2021. 16 Although the Pew Research Center report did not specify data on the use of social media as an information source for academic purposes, the diverging data between these two sources is intriguing. 17 Perhaps future research could address this dichotomy.

Social Media in the Higher Education Classroom

The literature reveals that social media has been incorporated into higher education classrooms for different purposes since the 2000s. 18 Perhaps due to students’ familiarity with social media, instructors often report using it to communicate with students, instructors often report using it to communicate with students, increase class participation, promote engagement with course topics, encourage further discussion outside the classroom environment, and build a sense of community among participants. 19 For example, Anatoly Gruzd et al. note that social media promotes “networked learning,” in which students connect beyond classmates and instructors to broader academic and social communities with shared interests. 20 Scholars also observe that social media’s popularity has grown for “formal and informal learning in many disciplinary areas.” 21

In addition, some studies address the advantages of including social media in the classroom, such as faculty exposing students to sources outside the traditional academic setting, and “promoting learning through social interaction and collaboration.” 22 Of particular interest to our study is the idea of expanding the learning environment, which Gruzd et al. align with “discovery,” permitting students and instructors to find and access resources outside traditional settings. 23

Another social media use in the higher education classroom relates to platform data analysis and career skills development. For example, Michele Ewing, et al. write about the importance of social media analytics for students in the public relations field, arguing that practical experience using tools and methods is vital for student success. 24 Similarly, other authors argue in favor of teaching strong social media skills in journalism programs, addressing news coverage and competencies to create content. 25 This disciplinary interest in various aspects of social media suggests there is value in including social media in IL instruction to support course curricula.

Social Media in Library Instruction

Social media literature connected to information literacy emerged in the early 2000s, showing that librarians have utilized social media to help students understand the quality of sources, share content, promote online collaboration, and discuss informal scholarly interaction. 26 However, as mentioned earlier, not many studies provide data on teaching librarians’ incorporation of social media as an information source in IL instruction. 27 One study—examining Mississippi academic librarians—found that, even when these librarians concurred that social media was an essential component of IL instruction that would improve students’ ability to consume, disseminate, and create information, fewer than half of them attempted or planned to use social media in their library sessions. 28

Benefits of Using Social Media as an Information Source in Instruction

Some librarians see benefits to using social media in instruction. Sheila Stoeckel and Caroline Sinkinson emphasize the value of social media concerning its, “participatory nature of research and knowledge negotiation,” as opposed to the passive collection of resources. 29 Additionally, Natalie Burclaff and Catherine R. Johnson invite librarians to go beyond the demonstration of databases to incorporate social media as a research tool to access different perspectives and voices. 30 Kim et al. also recognize that social media provides information not found in traditional academic sources, offering a broader range of voices and opinions to consider. 31 Other librarians encourage using social media as a source of information based on its ability to disseminate information, the usefulness of hashtags to cover subject headings, and its ability to engage students in the research process. 32

Students’ familiarity with social media is another potential benefit that some authors consider when addressing social media in instruction. Scholars note that students’ comfort and previous experience with social media help them to practice critical thinking and become a part of informal scholarly interaction by participating in discussions in library sessions. 33 Critical thinking is crucial for students when evaluating information and sources. In a discussion about the Association of College & Research Libraries’ Framework and metaliteracy, Valerie J. Hill and Thomas P. Mackey highlight the initial inception of metaliteracy to promote critical thinking and collaboration in social media and other digital communities. 34 The authors add that a primary goal for metaliteracy is for learners to, “actively evaluate content while also evaluating one’s own biases.” 35 Additionally, Casey Fiesler—addressing information reliability in news disseminated on TikTok—asserts that this platform may provide accurate information, but advises us to, “consider the credibility of sources and information we choose to believe and share.” 36

Challenges of Using Social Media as an Information Source in Instruction

Some authors have expressed concerns about social media as an information source. These concerns include privacy and ethical implications, disinformation, and instructor competency. 37 Alison Hicks and Caroline Sinkinson discuss privacy issues within active learning activities, cautioning that digital tools may expose learners to tracking and surveillance. 38 Regarding personal data shared on social media, Lucy Pangrazio and Neil Selwyn emphasize the importance of including social and ethical considerations in “digital literacy” instruction, noting that students need to know how to engage with social media responsibly. 39

Other scholars have voiced concerns about the quality of information available on social media. Donna Witek and Teresa Grettano recognized that social media is an environment where “formal and informal sources of information” meet, and where it is important to teach students how to evaluate information. 40 This concern results from information being generated within a social context that is “directly related to how others in their networks value that information and whether the information is relevant to their friends or to themselves.” 41

This literature review addressed college students’ use of social media for academic purposes, social media use in the classroom, and favorable and critical views on integrating social media in instruction. Our study seeks to address the gap in the literature, and to advance the scholarship by shedding light on whether teaching librarians utilize social media as a pedagogical tool in IL instruction, as well as considering how teaching librarians perceive the benefits and challenges of teaching social media in library sessions.

Methodology

This research paper seeks to answer the following questions:

How are teaching librarians using social media as an information source in their instruction?
What are the benefits teaching librarians perceive regarding the use of social media in instruction?
What are the challenges teaching librarians perceive regarding the use of social media in instruction?

We used a thirty-five-question Qualtrics survey approved by the University of Colorado Institutional Review Board. The branched survey had thirty-three multiple-choice questions and two free-text questions. The survey was open from August 13th to October 6th, 2021. Although 162 respondents filled out the survey, the number of individuals who completed each question varied. The data collected were quantitative and qualitative. The closed-ended questions gathered data on the participants’ institutional affiliations and responsibilities as academic librarians. The multiple-choice questions gathered data on social media platforms used in library instruction sessions, frequency of use, and type of use. The survey had two hybrid questions and two fully qualitative questions. Questions 32 and 33 utilized a hybrid question design, where partially close-ended questions allowed respondents to select from the options provided and write additional comments using the field “Other.” Questions 32 and 33 gathered data on the challenges and benefits of using social media in IL instruction. Questions 34 and 35 collected qualitative information in free-text boxes about librarians’ perceptions of faculty’s reaction to social media in IL instruction. We organized the data in a spreadsheet for analysis. See the Appendix for the complete survey instrument.

Participants

We distributed the survey via email to the following disciplinary listservs: the Association of College and Research Libraries, History Librarians Interest Group, Education and Behavioral Sciences Section, Literature in English Section, the Seminar on the Acquisition of Latin American Library Materials, the Council on East Asian Libraries, the Collaborative Initiative for French and North American Libraries, the Colorado Council of Medical Librarians, and the Engineering Library Division. We chose these organizations due to their connection with library instruction in academic libraries. Due to low levels of participation, we also distributed the survey directly through email to 139 librarians with teaching responsibilities at eleven universities. 42 We searched the directories of these university libraries, identified all librarians who appeared to have teaching responsibilities, and emailed them directly.

Our Approach to the Data

Our study used a survey research approach. We identified our target audience as librarians with teaching responsibilities. We designed the questionnaire and piloted it with three instruction librarians who provided feedback to improve this instrument. Rather than approaching the data with a pre-existing hypothesis, the two main authors conducted three rounds of coding. First, we individually identified keywords from each response to the four questions with qualitative data and organized these keywords (codes) in a spreadsheet. Second, we compared our keywords and agreed on themes. Third, we reviewed our data again and allocated each response to the thematic categories we created.

Respondent Demographics

Table 1 summarizes the relationship between social media use and respondents’ background information. We separated responses into “Yes” and “No” categories of social media use, based on whether the respondent selected the option: “I have not used social media platforms in my instruction.” This table shows that 110 of 139 respondents work in a university that confers doctoral degrees, with only 29 respondents at other types of institutions. Table 1 also shows how respondents identified the nature of their positions, with a large representation of subject specialists followed by librarians who categorized their positions as instruction and reference. The largest percentage of librarians who used social media were those who identified their job as involving “outreach.” However, this group represents a smaller pool of respondents compared to subject specialists or those who categorized their position as “instruction.”

In addition, respondents reported supporting a wide variety of departments and programs, ranging from the sciences and humanities to the social sciences. The small percentage of respondents who supported departments related to communication, journalism, and media studies utilized social media more frequently than those supporting other academic programs. While it is interesting to note some of these trends in the data, we make no statistical claims about the relationship between respondents’ background information and their social media use. Additional data collection is necessary to ensure adequate subgroup sample sizes before this analysis is useful.

Use of Social Media in Instruction

Figure 1 shows the social media platforms respondents used in their instruction sessions. Data indicate that 42 percent of 139 respondents do not use social media platforms in their library sessions. Fifty-eight percent of respondents noted that they had used social media platforms in IL instruction. This percentage represents all the purposes of use as listed in table 2, and not just social media as a source of information. Figure 1 also indicates that the online video-sharing platform YouTube, and the microblogging and social networking site Twitter, have the highest use in library instruction, with 38 percent and 35 percent, respectively. Over 20 percent of respondents utilized Facebook and Instagram in their instruction. However, seven of the eleven platforms considered in this study had minimal use in library sessions, with fewer than three respondents selecting Nextdoor (platform for reporting news and events at the neighborhood level,) Snapchat (multimedia instant messaging app,) and WhatsApp (instant messaging and voice-over-IP service).

Table 2 shows how respondents used social media platforms in their instruction sessions (81 respondents). Table 2 indicates that 33 respondents (40 percent) reported that they referred to social media platforms in their instruction, but did not demonstrate their use. In addition, table 2 shows that most respondents (38 respondents) utilized a platform in their instruction session to teach about the context of information and what information is available on social media, although none of the purposes selected were utilized by even half of the respondents. Fewer than 45 percent of respondents (36 respondents) utilized social media for teaching lessons on citing, copyright and fair use, or to teach evaluation skills.

Only 29 respondents (36 percent) used a social media platform to teach how to find information by scholarly sources; 25 respondents (31 percent) utilized a platform to teach how to find news and current events. Fewer than sixteen respondents used platforms to teach data analytics, how to create platform content, or to find solutions to problems. In addition, respondents utilized platforms for other purposes, such as student engagement and classroom community building, as table 2 indicates.

Figure 2 shows the three most utilized platforms (YouTube, Facebook, and Twitter), as well as their purpose of use related to social media as an information source. We chose seven “purpose of use” categories based on the number of respondents and on their relevance to teaching. Respondents most frequently used Twitter to teach: evaluation skills, lessons on fake news, context of information and what information is available, and how to find news and current events. Respondent utilized YouTube the most often to teach lessons on citing, and on how to find posts by scholarly sources. Respondents most often used Facebook as a reference, but respondents who selected this option did not demonstrate or use this platform in instruction.

Frequency of Use of the Eleven Platforms

Figure 3 represents how frequently respondents reported using each of the 11 social media platforms in their instruction. Data showed that Twitter and YouTube had the highest frequency of use of the eleven platforms, with nine respondents utilizing Twitter, and 16 utilizing YouTube about three times per semester or more. It is important to note that platform use totals in figure 3 may not match the totals in table 2, as not all respondents answered all survey questions.

Challenges When Using Social Media in Library Instruction

Figure 4 indicates that 36 percent of respondents selected “there are too many things to teach in a session to include social media in library instruction.” Nearly 25 percent of respondents indicated concern regarding fast technological changes and privacy issues. Figure 4 also shows that there was no substantial consensus when selecting challenges. In addition, fewer than ten percent of respondents noted that students lack the skills and become distracted. Only 20 percent of respondents agreed with the statement: “social media often contains unreliable information.” Ten percent of respondents felt apprehensive about their own technical skills.

Thirty-six percent of respondents selected the option “other,” not shown in figure 4. We coded their statements using keywords derived from respondents’ answers. The following keywords represent these answers about challenges to using social media in IL instruction: “not useful,” “changes in technology access,” “lack of support,” and “not suitable and not scholarly.” Three respondents did not answer this question directly; however, they displayed a pessimistic attitude towards social media, stating: “I am disgusted by social media, which pervades my instruction,” “Giving off the ‘hello fellow kids’ vibe,” and “I do not want to support social media platforms in general so I don’t want to encourage using them for any purposes…”

Benefits When Using Social Media in Library Instruction

Figure 5 shows that 55 percent of 92 respondents perceived students’ familiarity with social media as a benefit of including it in library instruction. Forty-one percent of respondents noted that social media provides access to voices not represented in academic sources, and 27 percent considered social media skills necessary for everyday life. Slightly more than 20 percent indicated that social media provides current information, adds entertainment to the instruction session, and demonstrates a topic well.

Twenty-two respondents (24 percent) noted additional benefits in the option “Other.” This “Other” category revealed a few minor themes in how librarian instructors see teaching social media as beneficial, including that the platforms provide a convenient and helpful medium for instruction. Three respondents reported using social media in this way, two of whom specifically named YouTube. The third remarked that “videos” help them to teach about using the library catalog. Another theme was that social media provided data for students to work with and analyze. Other individuals identified benefits such as social media allowing them to teach concepts in classes, reach broader audiences, and learn to interact with social media in ways essential for their academic field.

Reactions of Faculty in Academic Departments to Social Media in Library Instruction

Seventy respondents shared their perceptions about departmental faculty’s reactions to social media in library instruction in a free-text box. Twenty-four respondents selected “not applicable” (N/A), or did not answer the question. Figure 6 shows that forty-one percent of respondents perceived their faculty to react positively to using social media in library instruction. Some librarians commented that professors were curious, supported the evaluation of contextual information and real-life examples, found social media fun, trusted the librarian, or considered the inclusion of social media inconspicuous because it was used in a limited capacity in IL instruction.

General Comments from Survey Respondents

The survey’s final question asked respondents if they had anything else to share about using social media in instruction. Forty-two people provided comments. Eight respondents advocated for teaching social media in library instruction, suggesting that social media is a part of modern life used by students and researchers, and thus should be addressed in library sessions. Three respondents expressed an interest in learning more about how others included social media in their instruction, or about the support they received from their institutions. Some participants mentioned that social media was helpful to them for teaching concepts and ideas. Other comments included the importance of social media for scholarly communication, engagement and outreach, and research interests.

Research Question 1: How are Teaching Librarians Using Social Media in their Instruction?

Our data indicate that, while respondents are using social media platforms in instruction, they mostly use them to provide examples and to help students understand the current information landscape, but not as a source of information that could help students find resources for their academic assignments. Specifically, our findings show that many respondents had either used—or referred to—a social media platform in instruction to teach a concept (e.g., citation, evaluation, fair use) or for classroom community building (table 2). However, fewer librarians use social media platforms as a source of information to find posts by authoritative sources, to teach lessons on fake news, or to find news and current events.

As mentioned above, some librarians utilize social media for lessons about fake news and misinformation; however, most respondents did not prioritize this option. Considering the amount of literature published in library science journals on evaluating sources, metaliteracy, and the challenges of doing research in the age of misinformation, it is intriguing that the librarians who responded to our survey did not report more actively using social media to address fake news and misinformation in IL instruction. 43

On the other hand, respondents’ relatively low use of social media in library instruction to seek information from authoritative or scholarly sources is somewhat predictable. Social media’s reputation as a credible or even acceptable source of information has plummeted in response to many scandals, such as when people used social media platforms to spread false news during the 2016 U.S. presidential election, or when publications—such as the New York Times —highlighted the negative effects of social media on youth, and published articles related to the Facebook whistle-blower (which prompted Congress to call for increased regulation of this platform). 44 Despite the many critiques of social media, we wonder whether teaching librarians should introduce these platforms as a pedagogical tool for students to find information for academic work in higher education. To this end, we consider how respondents perceived benefits and challenges to including social media in library instruction.

Research Question 2: What are the Benefits Teaching Librarians Perceive Regarding the Use of Social Media in Instruction?

The two greatest benefits to using social media in IL that respondents identified were students’ familiarity with social media platforms, and the access social media provides to voices that are often not represented in academic sources (figure 5). Some respondents considered social media to be helpful for the development of skills for everyday life, the ability to demonstrate topics, and for providing access to current information. Additionally, a few respondents mentioned that social media provided data for analysis, and that it was good for instruction using videos, or for teaching a concept.

Since social media is a part of everyday life for many people, including higher education students, it is unsurprising that some librarians would seek to harness students’ familiarity and comfort with social media to teach them about library research. The survey data reflects this use: many librarians felt that students’ familiarity with social media helped them relate to library instruction topics. One respondent offered the statement: “Great evaluation examples.” Similarly, another respondent stated, “I use social media as an example in discussions about how information moves in online spaces…” These statements help us reflect on the possible uses of social media in IL instruction.

Another use of social media is the dissemination of underrepresented voices. Scholarly literature represents one source of information commonly recognized as academic due to the peer review process, but it is not the only source of information. Social media may allow access to additional, different voices—such as those of activists, Indigenous peoples, members of underrepresented communities, and governmental and non-profit organizations—as well as to different contexts for information. Kim et al. acknowledge social media’s function as a place where different voices may be found:

Social media takes[sic] advantage of the wide range of experiences and expertise that people have. While their quality varies, social media information sources can provide information that traditional resources cannot efficiently provide. It would therefore be beneficial to acknowledge their usefulness as information sources and to develop IL programs for helping individuals to effectively evaluate and use them. 45

While we acknowledge the benefit of student familiarity with social media in IL instruction, we consider the more important benefit to be the access to first-hand knowledge and experiences from a wide variety of perspectives it provides, which may broaden students’ exposure to different ideas, and to help them understand the world more comprehensively.

Question 3: What are the Challenges Teaching Librarians Perceive Regarding the Use of Social Media in Instruction?

Respondents identified three substantial challenges to using social media in IL instruction: limited time to cover more material in sessions; fear of not being up to date due to fast changes in technology; and concern about privacy issues (figure 4). The biggest challenge—the lack of time to cover social media in IL instruction—suggests that respondents view social media as an additional or “extra” topic, rather than a source of examples for concepts already integrated within their lesson plan. Since time is a major concern for librarians using the one-shot instruction model, one solution could be incorporating social media into the topics they already cover. This model could benefit students by teaching them evaluation skills, and by providing access to a wide range of voices they could include in their academic work.

Another challenge respondents identified relates to the amount of time required to stay current using these technologies. The quickly evolving nature of social media “poses[sic] significant challenges for users,” forcing them to develop new skills and different types of competencies constantly. 46 Recognizing that technology changes continually, and that social media will probably continue to exist, we wonder whether teaching librarians would consider planning lessons where social media is seen as a source of information.

Privacy was another challenge respondents identified, including privacy issues for themselves as well as for their students. However, only 41 out of 107 respondents selected privacy concerns as one of their top three challenges for including social media in IL instruction. This data is remarkable, as we anticipated that privacy would be a top concern for many respondents, given the criticism of social media companies who use information from user accounts and social media posts to target users with political propaganda and advertisements. Social media has also been criticized for exposing users to illegal data appropriation and compromising users’ accounts. These issues are relevant to our discussion because librarians using social media platforms in instruction may legitimize the use of social media platforms, which subsequently exposes students to these risks.

Another risk associated with the use of social media in IL instruction relates to students’ ethical use of platforms. To illustrate: if students decided within a class research activity to search for information about their classmates or instructor instead of the research topic, then students might be infringing on the privacy of others. For this reason, any IL instruction activity involving social media would need to be carefully designed to include a discussion about using platforms in an ethical, responsible, and safe manner. 47

Another topic that received surprisingly little interest from respondents was that of misinformation. Few librarians indicated that “unreliable information” was a challenge when using social media. Given the degree of attention this topic has received in both scholarly and popular spaces, it is curious that so few respondents would identify this as an issue. A few respondents included comments such as “inappropriate content,” and “not useful,” but none specifically referred to “fake news,” or similar concerns.

Librarians’ Perceptions of Faculty Attitudes Towards Social Media in IL Instruction

Our data suggest that many librarians perceived positive reactions from departmental faculty toward using social media in IL instruction. This positive reaction might encourage librarians to explore using social media in IL instruction for a variety of purposes, including using it as an information source for academic work. However, advocacy for social media could be difficult if teaching librarians have a negative attitude toward it.

A few respondents openly expressed disapproval of social media, suggesting that some librarians may not approve of using social media in IL instruction. As discussed earlier, librarians are often in the position of trying to teach a great deal of content in very limited time frames. Therefore, it is understandable that teaching librarians would not want to spend time on something they consider not useful in the academic context.

However, a negative attitude toward including social media in IL instruction could have consequences. Teaching librarians may miss an opportunity to help students use platforms critically and effectively for scholarly research or other information-gathering purposes. Additionally, ignoring social media and its impact on the world could prevent librarians from understanding how students look for information, generating a disconnect between librarians and students. As teaching librarians ourselves, we recognize the concerns about social media as a source of information for academic work. Nonetheless, we invite our colleagues to investigate further the pedagogical use of these platforms as a source of information in IL instruction.

Limitations to This Study

The data collected in this study represents the responses of a small number of participants within the United States. Therefore, the findings cannot be used to make generalized assumptions, and statistical information is considered exploratory. In addition, it was challenging to create keyword codes for some of the qualitative data due to difficulties in interpreting responses. The survey also presented a limitation concerning some of the multiple-choice questions, which prompted respondents to select from author-created options rather than allowing respondents to generate their own answers.

Our study examines whether and how teaching librarians are using social media in their IL instruction, as well as the benefits and challenges they encounter when they do so. The desire to include other voices and resources in addition to traditional scholarly perspectives in the academic narrative motivated this exploration.

Despite the challenges of utilizing social media in IL instruction, these platforms provide a medium for people to participate in global conversations, to share many types of information—as well as experiences, beliefs, and solutions to problems—that may otherwise go unnoticed by scholars, and that may be useful to students’ academic work. Finally, given the popularity of social media, it seems likely that people will continue to use it extensively, and that voices representing societal changes and trends may be found there. Therefore, we encourage librarians to participate in the conversation about incorporating social media and non-scholarly voices into IL instruction.

Topics for Future Research

Future studies could examine the attitudes of professors toward the use of social media in IL instruction and their expectations about students’ inclusion of non-scholarly voices in their academic work. Future research is also needed about the most effective methods of integrating social media into IL instruction.

Acknowledgments

The authors thank Victoria Kravets, Katie Stewart, and Gregor Rumenov Tzinov from the Laboratory for Interdisciplinary Statistical Analysis at the University of Colorado Boulder for their support in reviewing the statistical data in this paper and preparation of Table 1. We also thank Aditya Ranganath, Data Librarian at the University of Colorado Boulder, for his input about survey research. Finally, the authors also thank the University of Colorado Boulder’s Writing Center for assisting us during our writing process.

Appendix. The Survey Instrument

□ Yes
□ Yes, one time session (workshops, one-shots, webinars, etc.)
□ Yes, courses (multiple related sessions)
□ No instruction responsibilities.
□ Doctorate university
□ Master’s college/university
□ Baccalaureate college/university
□ Associate’s college/community college
□ Special focus institution/technical college
□ Tribal college
□ None of the above
□ 0-2 years
□ 3-5 years
□ 6-10 years
□ 11 or more years
□ Subject specialist/liaison
□ Instruction
□ Data services/GIS
□ Reference
□ Assessment/analytics/user experience
□ Archiving/curatorial/rare books/preservation/conservation
□ Digital initiatives/systems/information technology/web development
□ Outreach
□ Media/multimedia specialist
□ Access services
□ Cataloging/bibliographic control/metadata
□ Scholarly communication
□ Press/publishing
□ Acquisitions/collection development/management/strategy
□ Communication/journalism/media studies
□ Business
□ Math/computer science/statistics/technology/engineering
□ Social sciences
□ Natural sciences
□ Health/medicine/nursing
□ Education
□ Art/art history/theater/music/film
□ Social work
□ Undergraduate writing and rhetoric
□ Humanities
□ Literature
□ Languages
□ History
□ Other, please specify
□ I do not liaise with any department
□ Facebook
□ Instagram
□ LinkedIn
□ Nextdoor
□ Pinterest
□ Reddit
□ Snapchat
□ TikTok
□ Twitter
□ WhatsApp
□ YouTube
□ Other
□ I have not used social media platforms in my instruction
□ I’ve used Facebook to teach evaluation skills (accuracy, relevancy, currency, etc.).
□ I’ve used Facebook to teach lessons on fake news/misinformation.
□ I’ve used Facebook to teach lessons on citing, copyright, fair use, and/or Creative Commons.
□ I’ve used Facebook to teach content of information and what information is available in social media platforms (e.g., currency of posts, who can post information to this platform, etc.).
□ I’ve used Facebook to teach how to find posts or other information by the general public, or to observe social interactions.
□ I’ve used Facebook to teach how to find posts or other information by authoritative/scholarly sources.
□ I’ve used Facebook to teach how to find news and current events.
□ I’ve used Facebook to teach how to find instruction and solutions to problems.
□ I’ve used Facebook to engage with students with the goals of increasing classroom participation by using a familiar platform.
□ I’ve used Facebook to engage with students with the goals of communicating with students.
□ I’ve used Facebook to engage with students with the goals of building classroom community.
□ I’ve used Facebook to engage with students with the goals of creating relevant examples that students can relate to the instruction.
□ I’ve used Facebook to engage with students with the goals of teaching analytic and data skills for this platform.
□ I’ve used Facebook to teach platform-specific skills, such as how to use the platform in their future professions.
□ I’ve used Facebook to teach platform-specific skills, such as teaching how to create content for this platform.
□ I’ve taught Facebook or Facebook posts using the platform itself.
□ I’ve taught Facebook or Facebook posts using a 3rd party platform that makes the data available (e.g. Netlytic, Social Studio, etc.).
□ I’ve taught Facebook or Facebook posts using references to the platform, but I do not demonstrate or use the platform.
How do you use Instagram in your instruction sessions? Select all that apply.
How do you use LinkedIn in your instruction sessions? Select all that apply.
How do you use Nextdoork in your instruction sessions? Select all that apply.
How do you use Pinterest in your instruction sessions? Select all that apply.
How do you use Reddit in your instruction sessions? Select all that apply.
How do you use Snapchat in your instruction sessions? Select all that apply.
How do you use Tiktok in your instruction sessions? Select all that apply.
How do you use Twitter in your instruction sessions? Select all that apply.
How do you use WhatsApp in your instruction sessions? Select all that apply.
How do you use YouTube in your instruction sessions? Select all that apply.
You indicated you use an “other” social media platform. How do you use the “other” social media platform in your instruction sessions? Select all that apply.
□ Regularly, about three times per semester or more.
□ Once or twice per semester.
□ Rarely, about once a year or less.
How often do you use Instagram in your Instruction?
How often do you use LinkedIn in your Instruction?
How often do you use Nextdoor in your Instruction?
How often do you use Pinterest in your Instruction?
How often do you use Reddit in your Instruction?
How often do you use Snapchat in your Instruction?
How often do you use TikTok in your Instruction?
How often do you use Twitter in your Instruction?
How often do you use WhatsApp in your Instruction?
How often do you use YouTube in your Instruction?
□ Students get distracted.
□ I do not feel confident about my technical skills.
□ Students often do not have the technical skills needed.
□ I am concerned about privacy issues for myself.
□ I am concerned about privacy issues for students.
□ Technology changes fast, I don’t want to teach something outdated.
□ There are too many things to teach in a session to include social media.
□ Social media often contains unreliable information.
□ Some students do not have accounts to social media sites I present.
□ Students are familiar with social media and can relate to the instruction.
□ Students in my discipline need to learn social media skills for their future careers.
□ Working with social media keeps me up to date.
□ Social media demonstrate the topic very clearly.
□ Social media adds entertainment to the instruction session.
□ Social media provides access to voices not represented in academic sources.
□ Social media offers current information.
□ Social media skills are important for everyday life.
In your experience, how do most faculty/instructors from the departments you support react to social media in your library instruction?
Is there anything else you would like to share with us about your use of social media in instruction?

1. Danah M. Boyd and Nicole B. Ellison, “Social Network Sites: Definition, History, and Scholarship,” Journal of Computer-Meditated Communication 13 (2008): 214, https// doi.org/10.1111/j.1083-6101.2007.00393.x .

2. Brooke Auxier and Monica Anderson, “Social Media Use in 2021,” Pew Research Center , (April 2021), https://www.pewresearch.org/internet/2021/04/07/social-media-use-in-2021/ .

3. Andreas M. Kaplan and Michael Haenlein, “Users of the World, Unite! The Challenges and Opportunities of Social Media,” Business Horizons 53, no. 1 (2010): 61, https://doi.org/10.1016/j.bushor.2009.09.003 .

4. Auxier and Anderson.

5. For research on incorporating social media into the journalism curriculum, see: Ainara Larrondo Ureta and Simón Peña Fernández “Keeping Pace with Journalism Training in the Age of Social Media and Convergence: How Worthwhile is it to Teach Online Skills?,” Journalism 19, no. 6 (2018): 877-891, https://doi.org/10.1177/1464884917743174 ; For research on social media and teaching metaliteracy see: Donna Witek and Teresa Grettano, “Teaching Metaliteracy: A New Paradigm in Action,” Reference Services Review 42, no. 2 (2014): 188-208, https://doi.org/10.1108/RSR-07-2013-0035 . Also, Denny McCorkle and Janice Payan write about the demand for social media skills in business marketing and how students can learn practical job skills in the classroom to help them attain proficiency and confidence. These authors advocate for class projects involving Twitter to teach students how to communicate with consumers about new products, gather customer information, and monitor competitors. See: “Using Twitter in the Marketing and Advertising Classroom to Develop Skills for Social Media Marketing and Personal Branding,” Journal of Advertising Education 21, no. 1 (2017): 33-43.

6. Carrie Mastley points out the lack of literature about academic librarians’ attitudes to including social media in IL instruction in Mississippi. See: “Information Literacy Instruction and Social Media: A Survey of Mississippi Academic Librarian Attitudes,” Mississippi Libraries 83 , no. 3 (2020): 37, http://www.misslib.org/resources/Documents/MLarchive/ML2020Fall.pdf .

7. Jennifer Howard, “Social Media Lure Academics Frustrated by Traditional Publishing,” The Chronicle of Higher Education (February 2011).

8. Ian Rowlands, David Nicholas, and Bill Russell, “Social Media and Research Workflow,” Information Services & Use 31 (2011): 72, 82, 83, https://doi.org/10.3233/ISU-2011-0623 .

9. L. Pangrazio and N. Selwyn. “It’s not Like it’s Life or Death or Whatever: Young People’s Understanding of Social Media Data,” Social Media + Society 4, no. 3 (2018): 7.

10. Kyung-Sum Kim, Sei-Ching Joanna Sin, and Yuqi He, “Information Seeking through Social Media: Impact of User Characteristics on Social Media,” Proceedings of the American Society for Information Science and Technology 50, no. 1 (2013).

11. Ibid.

12. Kyung-Sun Kim, Sei-Ching Joanna Sin, and EunYoung Yoo-Lee, “Undergraduates’ Use of Social Media as Information Sources,” College & Research Libraries 75, no. 4 (2014): 442, 447, https://doi.org/10.5860/crl.75.4.442 . In a 2016 paper, Kim and Sin echoed Kim, Sin, and Eun Young Yoo-Lee’s 2014 study by stating that students use social media for information-seeking in the academic context. See Kyung-Sun Kim and Sei-Chin Joanna Sin, “Use and Evaluation of Information From Social Media in the Academic Context: Analysis of Gap Between Students and Librarians,” The Journal of Academic Librarianship 42 (2016): 76.

13. Deepti Khatri, “Use of Social Media Information Sources: A Systematic Literature Review,” Online Information Review Vol. 45 No. 6, 1039-1063, https://doi.org/10.1108/OIR-04-2020-0152 .

14. Ibid.

15. Kim, Sin, and Yoo-Lee, “Use and Evaluation of Information from Social Media: A Longitudinal Cohort Study,” Library and Information Science Research 43 (2021): 6, https://doi.org/10.1016/j.lisr.2021.101104 .

16. Auxier and Anderson.

17. Kim, Sin, and Yoo-Lee also noticed this discrepancy. See: “Use and Evaluation of Information,” 6.

18. Martin Rehm, Staphanie Manca, Diana Brandon, and Christine Greenhow, “Beyond Disciplinary Boundaries: Mapping Educational Science in the Discourse on Social Media,” Teachers College Record 121, no. 14 (2019): 2, https://doi.org/10.1177/016146811912101403 .

19. Lilian W. Mina, “Social Media in the FYC Class: The New Digital Divide,” in Social Writing/Social Media: Publics, Presentations, and Pedagogies , eds. Douglas M. Walls and Stephanie Vie, (The WAC Clearinghouse, 2018), 265, 270, 274, https://doi.org/10.37514/PER-B.2017.0063.2.14 , https://wac.colostate.edu/books/perspectives/social/ ; Sheila Stoeckel and Caroline Sinkinson, “Social Media,” Tips and Trends : Instructional Technologies Committee (Summer 2013): 1-5, https://acrl.ala.org/IS/wp-content/uploads/2014/05/2013summer.pdf ; Laurie M. Bridges, “Librarian as Professor of Social Media Literacy,” Library Innovation 3, no.1 (2012): 50; Jennifer Wright Joe, “Assessment of Social Media in the Library: Guidelines for Administrators,” Journal of Library Administration 55, no. 8 (2015): 671, https://doi.org/10.1080/01930826.2015.1085251 .

20. Anatoly Gruzd et al., “Uses and Gratifications Factors for Social Media Use in Teaching: Instructors’ Perspectives,” New Media & Society 20, no.2 (2018): 478, 489, https://doi.org/10.1177/1461444816662933 .

21. Rehm, Manca, Brandon, and Greenhow, 2; Referring to the integration of LinkedIn as a pedagogical tool, Mostafa Hamadi, Jamal El-Den, Sami Azam, and Narumon Sriratanaviriyakul found that collaborative learning could be achieved successfully in social media when instructors implement a well-defined framework for students. See: “Integrating Social Media as a Cooperative Learning Tool in Higher Education Classrooms: An empirical Study,” Journal of King Saud University Computer and Information Sciences 34 (2022): 3728.

22. Gruzd et al., 479, 488-9.

23. Ibid, 489.

24. Michele E. Ewin et al., “Teaching Digital and Social Media Analytics: Exploring Best Practices and Future Implications for Public Relations Pedagogy,” Journal of Public Relations Education 4, no. 2 (2018): 51–86.

25. Larrondo Ureta and Peña Fernández, 882.

26. Carrie P. Mastley states that social media connected with IL emerged with the appearance of Web 2.0 technologies. See: “Information Literacy Instruction and Social Media: A Survey of Mississippi Academic Librarian Attitudes,” Mississippi Libraries 83, 3 (2020): 34–36, https://doi.org/10.1515/opis-2020-0014 .

27. Heidi Julien, Melissa Gross, and Don Latham found that 14 percent of 343 librarians recruited from the ILI-L listserv—an American Library Association listserv related to information literacy instruction—use social media as a method of instruction. See “Survey of Information Literacy Instructional Practices in U.S. Academic Libraries,” College & Research Libraries 79, no. 2 (2018): 186. https://doi.org/10.5860/crl.79.2.179 .

28. Mastley, 42.

29. Stoeckel and Sinkinson, “Social Media,” 1–5.

30. Natalie Burclaff and Catherine R. Johnson, “Teaching Information Literacy Via Social Media: An Exploration of Connectivism,” Library Philosophy and Practice (2016): 7.

31. Kim, et al., “Undergraduates’ Use,” 453.

32. Jennifer Wright Joe refers to the dissemination of information. See “Assessment of Social Media,” 674; Amanda Kraft and Aleck F. Williams Jr., address the use of hashtags and promote the use of social media in library instruction alluding to the familiar environment platforms provide, see “#Shelfies are Encouraged: Simple, Engaging Library Instruction with Hashtags,” College &Research Libraries News (January 2016): 11, https://doi.org/10.5860/crln.77.1.9425 .

33. Kraft and Williams Jr.,“#Shelfies are Encouraged,” 11. Bridges suggests that librarians may guide students to apply critical thinking to their use of social media, “Librarian as Professor,” 49. Also, addressing participatory pedagogy, Wright Joe notes that social media provides opportunities for students to explore and participate in discussions. See: “Assessment of Social Media,” 675-676.

34. Valerie J. Hill and Thomas P. Mackey. “Embracing Metaliteracy Metamodern Libraries and Virtual Learning Communities,” College & Research Libraries News (May 2021): 2019-220.

35. Ibid, 221. Authors Diane M. Fulkerson, Susan Andriette Ariew, and Trudi E. Jacobson note that metaliteracy has four learning areas known as cognitive, behavioral, affective, and metacognitive, and that learners must be critical as evaluators and creators of information. See: “Revisiting Metacognition and Metaliteracy in the ACRL Framework,” Communications in Information Literacy 11, no. 1 (2017): 24-26. https://doi.org/10.15760/comminfolit.2017.11.1.45 . To review the ACRL framework, see “Framework for Information Literacy for Higher Education,” Association of College & Research Libraries (2016). http://www.ala.org/acrl/files/issues/infolit/framework.pdf .

36. Ally Dever, “Millions are Turning to TikTok for the Latest on Ukraine, But Can the Platform be Trusted?” CU Boulder Today (March 18, 2022). Retrieved March 22, 2022 from https://www.colorado.edu/today/2022/03/18/millions-are-turning-tiktok-latest-ukraine-can-platform-be-trusted .

37. Sarah Hartman-Caverly and Alexandria Chisholm argue that privacy literacy (PL) is minimally present in library instruction, and is more often addressed as an issue in the technology side of librarianship. See: “Privacy Literacy Instruction Practices in Academic Libraries: Past, Present, and Possibilities,” International Federation of Library Associations and Institutions Journal 46, no.4 (2022): 310, https://doi.org/10.1177/0340035220956804 ; Daniel G. Krutka et al., “Teaching ‘Against’ Social Media: Confronting Problems of Profit in the Curriculum,” Teachers College Record 121 (2019): 11, 16, 26, https://doi.org/10.1177/016146811912101410 ; Jamie Halliwell, “Applying Social Media Research Methods in Geography teaching: Benefits and Emerging Challenges,” Journal of Geography 119, no. 3 (2020): 110-111, https://doi.org/10.1080/00221341.2020.1755717 ; Stoeckel and Sinkinson, “Social Media,” 1-5.

38. Alison Hicks and Caroline Sinkinson, “Participation and Presence: Interrogating Active Learning,” portal: Libraries and Academy 21, no. 4 (2021): 759, https://doi.org/10.1353/pla.2021.0040 .

39. L. Pangrazio and N. Selwyn, “It’s not Like it’s Life or Death or Whatever: Young People’s Understanding of Social Media Data,” Social Media + Society 4, no. 3 (2018), 7. Stefania Manca, Stefania Bocconi, and Benjamin Gleason also refer to the connection between social media skills and digital literacies. See: “Think Globally, Act Locally”: A Global Approach to the Development of Social Media Literacy,” Computers & Education 160 (2021): 2-3.

40. Witek and Grettano, 201.

41. Ibid, 199.

42. We selected the top eleven universities according to a US News and World Report list. See: “Best National University Rankings,” U.S. News & World Report , accessed September 2021, https://www.usnews.com/best-colleges/rankings/national-universities . The librarians contacted worked for the following institutions: Princeton University, Harvard University, Columbia University, Massachusetts Institute of Technology, Yale University, Northwestern University, John Hopkins University, California Institute of Technology, University of Pennsylvania, University of Chicago, and Stanford University.

43. Citing Wardle and Derakshan, Claire McGuinness defines mis-information as “false information that is shared without meaning to cause harm;” dis-information as “false information that is shared knowing that it will cause harm;” and mal-information as “genuine information” that “is shared to cause harm, often by moving information designed to stay private into the public sphere.” See The Academic Teaching Librarian’s Handbook , (London, UK: Facet Publishing, 2021): 28; Claire Wardle and Hossein Derakhshan, “Information Disorder: Toward an Interdisciplinary Framework for Research and Policymaking,” Strasbourg: Council of Europe , (2017): 5; Ian O’Hara notes that information literacy helps learners to understand misinformation and computational propaganda in social media. See: “Automated Epistemology: Bots, Computational Propaganda & Information Literacy Instruction,” Journal of Academic Librarianship 48, no. 4 (2022), https://doi.org/10.1016/j.acalib.2022.102540 .

44. For reference to the spread of fake news during the 2016 U.S. presidential election, see: Mike Wendling, “The (Almost) Complete History of ‘Fake News,’” BBC News (22 January 2018), https://www.bbc.com/news/blogs-trending-42724320 . For reference to social media effects on youth see: Christina Caron, “Worried about your Teen on Social Media? Here’s How to Help,” The New York Times (Sept. 21, 2021), https://www.nytimes.com/2021/09/21/well/family/teens-social-media-help.html ; Erin Woo, “Teenage Girls Say Instagram’s Mental Health Impacts are no Surprise,” The New York Times (Oct. 5, 2021), https://www.nytimes.com/2021/10/05/technology/teenage-girls-instagram.html ; Jessica Grose, “The Messy Truth About Teen Girls and Instagram,” The New York Times (Oct. 13, 2021), https://www.nytimes.com/2021/10/13/parenting/instagram-teen-girls-body-image.html ; Amanda Hess, “How Social Media Turned ‘Prioritizing Mental Health’ Into a Trap,” The New York Times (Oct. 27, 2021) https://www.nytimes.com/2021/10/27/magazine/social-media-mental-health.html ; Kelly Browning, “Parents Sound Off on Testimony about the Harms of Facebook and Instagram,” The New York Times (Oct. 5, 2021), https://www.nytimes.com/2021/10/05/technology/parents-sound-off-on-testimony-about-the-harms-of-facebook-and-instagram.html . For reference to the whistle-blower hearing in Congress see: Sheera Frenkel, “Key Takeaways from Facebook’s Whistle-blower Hearing,” The New York Times (Oct. 5, 2021); Frenkel, “Whistleblower Discusses how Instagram May Lead Teenagers to Eating Disorders,” The New York Times (Oct. 5, 2021), https://www.nytimes.com/live/2021/10/05/technology/facebook-whistleblower-frances-haugen?partner=IFTTT#in-hearing-haugen-discusses-how-instagram-may-lead-teenagers-to-eating-disorders .

45. Kim, et al., “Undergraduates’ Use,” 453.

46. Hadewijch Vanwynsberghe, Ruben Vanderlinde, Annabel Georges, and Pieter Verdegem, “The Librarian 2.0: identifying a Typology of Librarians’ Social Media Literacy,” Journal of Librarianship and Information Science 47, No. 4 (2015): 284, https://doi.org/10.1177/0961000613520027 .

47. For more information about privacy issues in IL in connection to the digital environment, see Hicks and Sinkinson’s article “Participation and Presence,” 759.

* Kathia Salomé Ibacache Oliva is Romance Languages Librarian and Assistant Professor at University of Colorado Boulder, email: [email protected] ; Elizabeth Novosel is Faculty Fellow and Liaison & Projects Librarian at University of Colorado Boulder, email: [email protected] ; Stacy Gilbert is Social Sciences Librarian and Assistant Professor at University of Colorado Boulder, email: [email protected] . ©2024 Kathia Salomé Ibacache Oliva, Elizabeth Novosel, and Stacy Gilbert, Attribution-NonCommercial ( https://creativecommons.org/licenses/by-nc/4.0/ ) CC BY-NC.

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Open Access

Peer-reviewed

Research Article

Vowel onset measures and their reliability, sensitivity and specificity: A systematic literature review

Roles Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Resources, Validation, Visualization, Writing – original draft, Writing – review & editing

* E-mail: [email protected]

Affiliation Voice Research Laboratory/ Doctor Liang Voice Program, Discipline of Speech Pathology, Faculty of Medicine and Health, Sydney School of Health Sciences, The University of Sydney, Sydney, NSW, Australia

Roles Data curation, Formal analysis, Investigation, Writing – review & editing

Roles Data curation, Formal analysis, Writing – review & editing

Roles Data curation, Writing – review & editing

Affiliation Division of Phoniatrics and Paediatric Audiology at the Department of Otorhinolaryngology Head & Neck Surgery, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Bavaria, Germany

Roles Data curation

Affiliations Division of Phoniatrics and Paediatric Audiology at the Department of Otorhinolaryngology Head & Neck Surgery, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Bavaria, Germany, Department of Computer Science, Chair of Computer Science 5, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Bavaria, Germany

Roles Conceptualization, Formal analysis, Investigation, Writing – review & editing

Antonia Margarita Chacon,
Duy Duong Nguyen,
John Holik,
Michael Döllinger,
Tomás Arias-Vergara,
Catherine Jeanette Madill

Published: May 2, 2024
https://doi.org/10.1371/journal.pone.0301786
Peer Review
Reader Comments

To systematically evaluate the evidence for the reliability, sensitivity and specificity of existing measures of vowel-initial voice onset.

A literature search was conducted across electronic databases for published studies (MEDLINE, EMBASE, Scopus, Web of Science, CINAHL, PubMed Central, IEEE Xplore) and grey literature (ProQuest for unpublished dissertations) measuring vowel onset. Eligibility criteria included research of any study design type or context focused on measuring human voice onset on an initial vowel. Two independent reviewers were involved at each stage of title and abstract screening, data extraction and analysis. Data extracted included measures used, their reliability, sensitivity and specificity. Risk of bias and certainty of evidence was assessed using GRADE as the data of interest was extracted.

The search retrieved 6,983 records. Titles and abstracts were screened against the inclusion criteria by two independent reviewers, with a third reviewer responsible for conflict resolution. Thirty-five papers were included in the review, which identified five categories of voice onset measurement: auditory perceptual, acoustic, aerodynamic, physiological and visual imaging. Reliability was explored in 14 papers with varied reliability ratings, while sensitivity was rarely assessed, and no assessment of specificity was conducted across any of the included records. Certainty of evidence ranged from very low to moderate with high variability in methodology and voice onset measures used.

Conclusions

A range of vowel-initial voice onset measurements have been applied throughout the literature, however, there is a lack of evidence regarding their sensitivity, specificity and reliability in the detection and discrimination of voice onset types. Heterogeneity in study populations and methods used preclude conclusions on the most valid measures. There is a clear need for standardisation of research methodology, and for future studies to examine the practicality of these measures in research and clinical settings.

Citation: Chacon AM, Nguyen DD, Holik J, Döllinger M, Arias-Vergara T, Madill CJ (2024) Vowel onset measures and their reliability, sensitivity and specificity: A systematic literature review. PLoS ONE 19(5): e0301786. https://doi.org/10.1371/journal.pone.0301786

Editor: Li-Hsin Ning, National Taiwan Normal University, TAIWAN

Received: August 29, 2023; Accepted: March 21, 2024; Published: May 2, 2024

Copyright: © 2024 Chacon et al. This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: All relevant data are within the manuscript and its Supporting Information files.

Funding: Contributions by MD were supported by Deutsche Forschungsgemeinschaft (DFG) under grant no. DO1247/8-2. Contributions by TA were supported by Deutsche Forschungsgemeinschaft (DFG) under grant no. SCHU3441/3-2. Contributions by AC, DN and JH were supported by the Doctor Liang Voice Program at The University of Sydney. The funders had no role in study design, data collection and analysis, decision to publish, nor preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.

Introduction

Measures of voicing control provide critical insight into a myriad of voice diagnoses across the lifespan. Voice disorders are highly prevalent, with an estimated one in thirteen adults experiencing a voice disorder each year [ 1 ]. Early and accurate diagnosis are essential to optimise patients’ vocal health outcomes. Traditionally, voice assessment and the evaluation of voice rehabilitative outcomes have focused upon voice quality [ 2 , 3 ] and patient-reported outcomes [ 4 ] as measures of voice function and efficiency. This assessment proforma typically involves the collection of a patient’s case history information, acoustic voice assessment and auditory perceptual judgement of the patient’s voice quality. Ideally, these tasks are also supplemented by laryngostroboscopic and aerodynamic assessment [ 5 , 6 ]. Most current voice assessment methods prioritise steady-state phonation with little, if any focus placed upon the initiation of voicing. Voice onset predicts the voice function that follows and as such, has been increasingly suggested as an effective means of assessing one’s voice, providing predictive information about phonation type, facilitating voice disorder diagnosis and determining one’s response to treatment [ 7 – 10 ].

Voice onset refers to the span of time between the release of a sound and the onset of voicing and involves several physiological processes. The onset of voice begins with transglottal airflow from the lungs bypassing the larynx and the start of vocal fold adduction. Small-amplitude, irregular vibration occurs at the edges of the vocal folds bordering the open glottis. Following the first instance of medial vocal fold contact, the amplitude of these vibrations grows, and steady-state oscillations are established [ 11 , 12 ]. The various physiological components involved in the onset of voice introduce many different means of voice onset measurement. There is also the compounding issue of differing types of voice onset. These are most commonly referred to as soft, breathy and hard, which are discernible to varying degrees depending on the measurement used.

There are two types of voice onset; one occurs after the release of a stop consonant and the other involves vowel phonation without a preceding consonant. Measures of voice onset which focus on the interval between the initial burst of a stop consonant and the voicing onset of the following vowel, e.g., ‘Voice Onset Time’ (VOT) [ 13 ], have been studied widely across populations and health statuses for many decades. The seminal papers in the voice onset literature typically relate to these such contexts of voice onset [ 14 – 18 ], as do most papers within the voice onset literature [ 12 ], with definitions of vowel-initial voice onset often being less clear. The onset of voicing which occurs when a vowel follows a consonant (CV), versus vowel-initial contexts of voicing varies considerably from a measurement perspective. CV measurement requires the ability to detect and differentiate between a consonant and vowel sound before analysing the vowel onset production, while vowel-initial contexts involve detection and measurement from the very start of voicing. Vowel-initial voice onset measurement is more clinically relevant than the measurement of CV productions, as vowel production is one of the standardised tasks performed in voice assessment [ 19 – 21 ]. It also allows for an indication of a patient’s voice production without the articulatory influences which are present in consonant-initial contexts [ 22 ]. Furthermore, the classification of voice onset types has been based primarily on vowel-centric tasks, and not upon vocal productions commencing with a consonant sound [ 7 , 23 ], and yet, vowel-initial voice onset has been researched to a lesser extent than CV voicing. As such, exploring the current state of the literature for specifically vowel-initial voicing onsets has been selected as a focus for this review.

The means through which voice onset has been measured across the existing evidence base is highly variable and has evolved with technological advances over time. Researchers measure voice onset through a range of measurement types, such as auditory perceptual measures, which involve making a judgement about the properties of a sound [ 23 – 25 ]; aerodynamic measures, such as phonatory airflow, volume and pressure [ 26 – 28 ]; physiologically, which monitors the physiological muscle movement associated with voice onset [ 11 , 29 , 30 ]; acoustically, which examines voice signal characteristics related to speech and voice production [ 12 , 31 , 32 ]; visually, through high-speed laryngoscopic examination of the vocal fold vibration associated with voice onset production [ 33 – 35 ], or through a combination of these [ 36 – 38 ]. Each of these methods of voice onset measurement present their own respective strengths and weaknesses, pertaining to the ability of each measure to reflect phonatory function or account for speaker variability, the reliability, sensitivity and specificity of the resulting measurement values, and factors associated with specific equipment requirements, training or skill-level in performing each measurement type. Nonetheless, no literature yet exists which has synthesised and consolidated the measures of voice onset which have been investigated, which are the most reliable, specific and sensitive in identifying or differentiating voice onset types, the contexts in which these measures may best be used, nor established a common language amongst voice onset types and the implications of these upon vocal function. It is imperative that these research gaps be filled so that valid clinical measures of voice onset can be established, which, in turn, can facilitate the inclusion of vowel onset measurement as part of the standardised clinical voice assessment proforma. The aim of this systematic review is to evaluate the evidence for sensitivity, specificity and reliability of vowel-initial voice onset measures, with the authors hypothesizing that high reliability, sensitivity and specificity ratings will indicate the most effective measures of vowel onset. To this end, the proposed systematic review will answer the following question: What are the methods of assessing vowel-initial voice onset and the evidence for their reliability, sensitivity and specificity?

Protocol and registration

This retrospective systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) [ 39 ]. The protocol was registered through the PROSPERO International Prospective Register for Systematic Reviews (registration number CRD42021266384) and is provided in S1 File . The completed PRISMA 2020 checklist is provided in S1 Checklist .

Information sources

Databases searched were MEDLINE via OVID, EMBASE via OVID, Scopus, Web of Science, IEEE Xplore, CINAHL and PubMed Central. Grey literature was also searched through ProQuest to capture unpublished dissertations.

Search strategy

The initial search was conducted by AC in August 2021 and limited to articles published after January 1900. The search strategy was initially determined through discussions between four authors (AC, CM, MD, DN). The first author also conducted an updated search in December 2022 and May 2023 to capture any further articles of relevance ahead of publication.

The search string consisted of terms relating to three ‘concept areas’: voice onset, voice onset measures and evidence for measures of voice onset. Within the selected concept areas, we developed a list of synonyms and/or specific terms relevant to our search scope. The terms associated with each concept area were searched against the other concept word lists to achieve literature saturation of all relevant articles. The search strategies and Boolean operators applied to the MEDLINE, EMBASE, Scopus, Web of Science, IEEE Xplore, CINAHL, PubMed Central and ProQuest databases are provided in S2 File .

Inclusion criteria

The scope of this literature review was the onset of vowel phonation without a preceding consonant. Studies and unpublished works were included if they were written in English, related to measures of human voice onset and were published after 1900. Nil study design limits were enforced, nor were specific settings of interest; research occurring in both laboratory and clinical settings were included. Articles were excluded if they related to the onset of artificial or computerised tones, examined voice onset in vowels following the production of a consonant sound (i.e., Voice Onset Time) and/or were not written in the English language.

Study records

The database searches retrieved 6,983 records. These records were uploaded to the Covidence platform ( www.covidence.org ) to manage data, facilitate collaboration and document the review process over the course of the study.

Covidence identified 550 duplicates which were then removed for a total of 6,433 records. Titles and abstracts were screened against the inclusion criteria by two independent reviewers (any combination of MD, AC, DN, JH and TA). Any disagreements which arose between the reviewers at each stage of the selection process were resolved through the involvement of a third reviewer. Five thousand, nine hundred and twenty-two records were excluded based on titles and abstracts, with a further 11 studies being excluded as their papers could not be retrieved. Full texts of the remaining 500 records were assessed in detail against the inclusion criteria by two independent reviewers (any combination of DN, AC, MD, TA, JH and CM). Articles that did not meet the study criteria were removed, with reasons for exclusion being recorded. Four hundred and seventy-two papers were excluded from this process. For the purposes of literature saturation, a further hand search of the remaining articles’ citation lists was conducted (AC). Following a further process of title/abstract screening (MD, AC, DN, JH and TA), full text review and exclusion of inappropriate studies (AC, DN, MD, JH and TA), an additional seven studies were included.

An updated review of the literature was conducted in December 2022 and May 2023. The processes of title/abstract screening (AC, DN, JH), full text review and exclusion of inappropriate studies (AC, DN, JH), were again completed. The December 2022 search found nil further studies appropriate for inclusion, while the search conducted in May 2023 identified a further two studies. The final systematic review included 35 studies. A visual representation of this process is shown in Fig 1 , formatted according to the PRISMA 2020 statement [ 39 ].

PPT PowerPoint slide
PNG larger image
TIFF original image

https://doi.org/10.1371/journal.pone.0301786.g001

Data extraction and data items

Data was extracted from the included papers by all members of the research team. The data extraction process involved each team member reading the paper in its entirety, before extracting all information of relevance into the data extraction table. A simplified version of this table is presented in S3 File and the OSF Home Repository (DOI 10.17605/OSF.IO/N65SX ). Quantitative synthesis and meta-analyses were not completed owing to the heterogeneity of data and methodologies across studies. Rather, studies were grouped according to their voice onset measurement category (see Table 1 ). Following the study groupings, the data extracted from all studies across each measurement category was closely examined to identify key relationships and discrepancies across and between papers and categories. This informed the key research findings which are summarised in the Results section.

https://doi.org/10.1371/journal.pone.0301786.t001

Evaluation of certainty of evidence and risk of bias

The certainty of the included evidence was assessed through the Grading of Recommendations Assessment, Development and Evaluation (GRADE) working group methodology [ 40 ]. This involved each reviewer examining the quality of evidence through the domains of risk of bias, consistency, precision, directness and publication bias. This was particularly facilitated using the GRADE Handbook [ 41 ], which was used by team members to inform their assessment and provide a consistent evaluation across raters. Following this evaluation, it was determined whether the quality of the research could be deemed as high (i.e. very unlikely that further research will change our confidence in the estimate of effect), moderate (i.e. likely that further research will have an impact on our confidence in the estimate of effect and may change the estimate), low (i.e. very likely that further research will have an important impact on our confidence in the estimate of effect and is likely to change the estimate), or very low (i.e. very uncertain about the estimate of effect). The GRADEpro app was used to facilitate this process and ensure that the abovementioned terms were informed by a consistent, systematic process [ 42 – 44 ].

Process of identifying studies

The PRISMA flowchart in Fig 1 outlines the processes undertaken to collect and review the study records. Thirty-five records were identified as meeting the inclusion criteria for the review. Twenty-three studies involved visual imaging, 19 studies conducted acoustic analysis, 11 used physiological measures, seven studies involved auditory perceptual analysis, and four included aerodynamic analysis.

Study design

Of the 35 studies included, 26 used a cross-sectional design, six were validation studies, two were review papers with single or multiple case examples and one was a cohort study. No study used a randomised controlled trial design.

Study population characteristics

Table 1 presents an overview of each record included in the review, summarising study setting, participant characteristics, category of measurement and evidence certainty. It should be noted that while some studies specified the setting in which their research took place, most settings could only be extrapolated from the study methodology. Studies which used data from only vocally healthy, normophonic speakers (i.e., non-patients) were classified as taking place in a laboratory setting. Studies which involved patients with some form of voice disorder diagnosis were classified as ’clinical’. However, only one study explicitly stated that patients were recruited directly from a voice clinical setting [ 34 ]. Table 2 offers a summary of study population characteristics across the collective paper set, including sample size, age, gender, vocal health status and setting.

https://doi.org/10.1371/journal.pone.0301786.t002

Voice onset types

A definition of voice onset was provided in 25 of the 35 studies (see S1 Checklist ). Ten of these provided definitions of the specific voice onset measures used throughout the study (e.g., Vocal Attack Time), and 15 included the concept of voice onset being the period between the first adductory movement of the vocal folds and steady-state vibration. Twenty-one studies specifically examined different types of voice onset, namely being breathy (also referred to as ‘aspirate’), normal (also referred to as ‘comfortable’, ‘soft’, ‘easy’ and ‘modal’) and hard (also referred to as ‘glottal’, ‘pressed’ and ‘hard/glottal attack’) voice onset types.

Whilst these are auditory perceptual classifications, not all studies compared or validated their instrumental measures with independently-rated auditory perceptual judgements, despite using voice onset type as a classification or identifier. Only three studies of the review set compared their instrumental measure to perceptual judgements. As auditory perceptual judgement of voice is considered the ‘gold standard’ of voice assessment [ 61 ], it is noteworthy that few studies used comparisons to auditory perceptual judgements to validate the measure being investigated.

Across the 35 studies, a wide range of voice onset measures were explored. Amongst these, some focused on a singular measure (e.g., laryngeal reaction time) whilst others examined one measure using several means of instrumentation, for example, Vocal Attack Time (VAT), which is measured using the vocal acoustic and glottographic signals. Other studies examined or compared several measures of voice onset. Overall, 39 different measures of voice onset were identified across the collective set. Our team mutually agreed that the best means of synthesising and presenting this heterogeneous data set was through grouping the studies according to their measurement approach. As such, the following categories of measurement were identified; acoustic, aerodynamic, auditory-perceptual analysis, physiological measures and visual imaging. In any case where a given study explored more than one category of measurement, it was included across all relevant categories. The collective findings across each of these measurement categories are outlined in the sections below.

Voice onset measures

In total, there were 39 voice onset measures across the collective dataset. These are presented with their definitions in Table 3 . These measures were developed and investigated using different methods of analysis, which are described in the following text.

https://doi.org/10.1371/journal.pone.0301786.t003

Categories of voice onset measurement

A) auditory perceptual analysis..

Auditory perceptual analysis involves a listener making an auditory judgement about the properties of a sound. In the case of voice onset studies, this judgement often relates to the type of onset produced. Seven of the 35 included studies involved auditory-perceptual analysis. All seven studies involved perceptual ratings of phonation onset type, ranging from soft to hard [ 23 – 25 , 37 ], breathy to ‘German’ (a glottal plosive occurring in German classical singing) [ 36 ] and breathy to hard/ pressed [ 7 , 38 ]. For four of the seven studies [ 7 , 36 – 38 ], the auditory perceptual rating of samples was used only as a form of correlation to an instrumental measure of voice onset. This also served as confirmation that the participants had produced the onset types correctly before proceeding with other voice onset measurements; with 67% concordance between the attempted phonation type and rater in Shiba and Chhetri’s study, 68% agreement reported in Cooke et al.’s paper, 80% of samples being correctly identified in Freeman et al.’s study and 100% agreement on attack types in Koike’s study. Each of the studies explored different measures of voice onset, with three studies examining auditory perceptual judgements of voice onset as a voice onset measure in and of itself. Peters, Boves and Van Dielen, Maryn and Poncelet and Simon and Maryn’s papers focused on auditory perceptual judgement of voice onset as a standalone voice onset measure, with Maryn and Poncelet and Simon and Maryn concluding that there was considerable variability both between and within raters regarding the perception of voice onset type. Meanwhile, Peters reported moderately high reliability of ratings (r 1.1 = 0.74).

Automation of voice onset measurement was involved in four of the seven studies, and only in the processing and data generation stages for measures unrelated to auditory perceptual analysis. All seven studies performed some form of reliability analysis, which is presented in Table 4 . Two studies conducted both inter- and intra-rater reliability [ 24 , 25 ], with the remainder only exploring inter-rater reliability. Percentage agreement [ 7 , 36 – 38 ], product-moment correlations [ 23 ], the intraclass correlation coefficient [ 24 , 25 ] and Cohen’s kappa [ 25 ] were the statistical measures used to calculate reliability. None of the seven papers explored sensitivity nor specificity of data obtained.

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Collectively, the studies presented conflicting findings. Whilst Freeman et al., Peters et al. and Koike’s papers suggested listeners could discriminate well between onset types, Cooke et al., Shiba and Chhetri, Maryn and Poncelet and Simon and Maryn’s papers indicated that auditory perceptual judgement of voice onset type can be unreliable both within- and between-raters. Six of the studies reflect the lowest GRADE level of evidence with a rating of ‘very low’ evidence certainty and one with a rating of ‘low’ certainty of evidence. This low quality of research evidence combined with the variability in the findings of these studies calls into question the value of auditory perceptual judgements as the most accurate and reliable means of assessing voice onset in clinical contexts. A summary of data extracted from these auditory perceptual studies is provided in Table 5 .

https://doi.org/10.1371/journal.pone.0301786.t005

b) Acoustic analysis.

Acoustic analysis involves examining the recorded voice signal characteristics related to speech and voice production. Amongst the studies included, 19 utilised acoustic analysis in their voice onset measurement procedures. A wide range of acoustic voice onset measures were explored, as summarised in Table 6 , inclusive of Vocal Rise Time (VRT), the first peak of the acoustic derivative waveform (ADW1) and Laryngeal Reaction Time (LRT). Papers exploring most acoustically derived measures of voice onset did not typically provide numeric data for each onset type. Rather, these presented data ranging from descriptions of onset type differences, such as vibration and amplitude patterns, often in the absence of complete data reporting (for example, [ 30 ]), to small datasets regarding a new or uncommonly used voice onset measure. A common feature across all presented acoustic measures was the limited utility of applying these measures in clinical contexts, with many requiring specialised software or processes which would be expensive and/or impractical to complete during a clinical session.

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No specifications of voice recording equipment were provided for model number nor brand for six studies and two studies provided no specification whatsoever of device used. An integrated microphone (I.e., a microphone integrated into a stroboscopy or similar system) was used in two studies, and a further three studies used an audiotape recorder. Only one of the devices was used across more than one study (RadioShack 33–3012 head-mounted microphone), however all three studies in which it was used involved a similar research team. Some form of automation was involved in the methodology of 14 of the included acoustic analysis studies, and usually this was across both the processing and data generation stages using software platforms and mathematical algorithms. Three of the included papers used auditory perceptual analysis as a means of validating the instrumental measures used [ 36 – 38 ].

Only seven studies reported reliability assessment of acoustic analysis, of which two explored both inter- and intra-rater reliability [ 12 , 35 ] and five explored only inter-rater reliability [ 23 , 36 – 38 , 54 ]. The following statistical methods were used to determine reliability across the studies: Pearson product-moment correlation [ 12 , 23 , 51 , 54 – 56 ], percentage agreement [ 36 , 37 ] and multivariate tests [ 35 ]. One of the studies that used acoustic measurements for voice onset reported sensitivity analysis [ 35 ], with none conducting an analysis on specificity.

In summary, the included acoustic analysis studies reflected low evidence certainty, with outcomes from the GRADE Certainty Assessment yielding a ’very low’ rating for 14 studies, and a rating of ’low’ for the remaining five. While a large proportion of the reviewed studies involved acoustic analysis measures, there is evidently a vast range of acoustic analysis measures being used which prevents an in-depth understanding of any given measure. The acoustic analysis findings overall cannot be interpreted with high levels of confidence, nor are they of sufficient quality to inform the selection of the most reliable, sensitive, and specific acoustic voice onset measures for clinical practice.

c) Aerodynamic analysis.

Aerodynamic analysis refers to the measurement of phonatory airflow, volume, pressure and combined measures, such as efficiency and resistance. Four papers reported airflow measurement information informing some aspect of voice onset. The specific airflow measures explored across these studies included air consumption during the initial 200 milliseconds of different attack types (soft, breathy and hard) [ 37 ], Phonation Threshold Pressure (PTP) [ 27 ], Voice Onset Coordination (VOC) [ 28 ] and vocal onset according to transglottal airflow and intraglottal pressure [ 26 ].

Koike and LeBacq and DeJonckere’s papers similarly focused their studies upon exploring the characteristics of different voice onsets. Koike identified that soft and hard onsets were diametrically opposed across a range of measures, while the breathy onset showed little relation to either, having a ‘distinct character’ that differed completely from soft and hard onset types. LeBacq and DeJonckere namely used their airflow data as part of an intraglottal pressure calculation, while Madill et al.’s study correlated existing voice onset measures, including VOC, with the measure ADW1, concluding that it can be predicted from VOC. In Plant’s exploration of phonation threshold pressure, it was found that for most subjects, increasing airway resistance coincided with increasing threshold pressure.

Devices used for airflow measures were largely consistent, with three of the four studies using a Rothenberg mask or equivalent, and the other paper using a pneumatochograph [ 37 ]. Most of the four papers didn’t involve any automated processes, apart from Madill’s study, which involved some automation only in the data generation phase. Only Koike’s study involved some form of reliability assessment, being inter-rater reliability established through percentage agreement. None of the studies performed an analysis of sensitivity nor specificity. None of the included papers used auditory perceptual ratings to validate the instrumental measures of voice onset used.

Overall, the aerodynamic data presented across these four studies did not contribute significantly to an understanding of the most effective means of assessing voice onset through airflow. Other than Koike and Madill, there is a lack of transparency when it comes to presentation of the aerodynamic voice onset data. These findings should be considered as offering indefinite conclusions pertaining to the value of aerodynamic voice onset measurement, particularly as all four studies were graded as having the lowest certainty of evidence, being ‘very low’ evidence certainty according to the GRADE rating system. A summary of these aerodynamic analysis studies is provided in Table 7 .

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d) Physiological measures.

A range of other instrumental measures that monitor physiological muscle movement have been used to measure voice onset. For the purposes of this review, this specifically relates to electroglottography (EGG) and electromyography (EMG). EGG is a non-invasive technology used to measure the varying degrees of vocal fold contact during voice production, while EMG is a measure of muscular response or activation. Eleven studies explored physiological measures of voice onset. The specific types of voice onset measures examined in these studies included VAT [ 11 , 28 , 29 , 51 , 52 , 55 , 56 ], maximum of the first derivative of the EGG signal [ 27 ] and the interval between the first action potential (as detected by EMG) and the onset of sound [ 37 ].

The three studies of low evidence were largely conducted by the same research group [ 51 , 52 , 56 ], and all explored VAT as a measure of voice onset. However, the research questions posed in each of these studies differed, ranging from determining the fidelity of VAT as a voice onset measure to establishing normative VAT values. Pearson’s correlation coefficient was found to be a suitable fidelity metric (median correlation coefficient of 0.975 for 1033 VAT measures) [ 51 ], with the mean VAT among healthy young adults reported as 1.98ms. Aspirated voice onsets (e.g., the production of ‘hallways’) lead to a greater mean VAT than unaspirated voice onset tasks (e.g., the production of ‘always’) [ 56 ]. All remaining studies were of ‘very low’ evidence certainty; the majority of which also explored VAT.

Devices used across the physiological studies were varied, with three studies providing no specification of equipment. The remaining eight studies included one electromyograph and the remainder a combination of electroglottographs of different brands and models, with only the Glottal Enterprises EG2 and the KayPENTAX Fourcin Laryngograph model 6091 occurring in more than one study (each used in two studies). Six of the included studies involved automation as part of their study methodology for physiological measures, with five of these employing automated processes or algorithms across both the data processing and generation stages and one only using automation for data generation.

Reliability analysis was only performed in one study; Koike, 1967, which conducted inter-rater reliability as determined through percentage agreement (see Table 4 ). Neither sensitivity nor specificity analysis was conducted in any of the papers within this category. Only one of the papers in this set included auditory perceptual analysis to validate the instrumental measures of voice onset used.

Collectively, the studies of the highest GRADE level of evidence examining physiological measures of voice onset use VAT. Despite the greater breadth of research upon VAT than most other voice onset measures, there is a requirement to collect both electroglottographic and acoustic data to attain the VAT value. This, combined with the limited availability of the MATLAB-based program to calculate the measure, the heterogeneity amongst research questions posed in these studies, and the highest evidence rating according to the GRADE rating system as ‘low’ calls into question its clinical utility. A summary of the studies involving physiological analysis is provided in Table 8 .

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e) Visual imaging.

Visual imaging relates to any study whereby a measure of voice onset was based upon still or motion pictures of the larynx. Amongst the 35 included studies, 23 involved visual imaging in their measurement of voice onset. These studies investigated a range of measures related to voice onset, including Phonation Onset Time (POT) [ 38 , 48 , 50 , 59 ], measures of velocity, angle, distance and time associated with voice onset [ 7 ], Voice Initiation Period (VIP) [ 35 , 46 , 50 ] and Glottal Attack Time (GAT) [ 34 ].

Twenty of the 23 studies in this category involved high speed visual imaging, with kymography used in five studies [ 11 , 36 , 38 , 53 , 60 ], rigid laryngoscopy in one [ 7 ] and one employing cine-radiographic techniques, i.e., the recording of laryngeal movements on x-ray film [ 37 ]. Devices used across the visual imaging studies were varied, with the most common device used being the KayPENTAX colour high speed video system and component model 9710, used in five of the 23 studies. Six studies did not specify the device used, and of the remaining studies, 11 used some form of high-speed camera system and the remaining study performed cineradiography. Nineteen studies utilised a software program or mathematical algorithm to automate the processing and/or analysis of data pertaining to vocal fold vibration and glottal characteristics ( Table 9 ).

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Ten studies used reliability assessment in their measurement protocols, involving three which explored both inter- and intra-rater reliability [ 12 , 33 , 35 ], five inter-rater [ 7 , 34 , 36 – 38 ] and two intra-rater reliability assessments [ 49 , 50 ]. The statistical methods used for reliability assessment included Pearson product moment correlations [ 12 , 49 ], Cohen’s kappa [ 33 ], Cronbach alpha [ 50 ], Pearson’s correlation coefficient, general linear model and repeated measures analysis [ 35 ], the Wald 99% confidence interval [ 34 ] and percentage agreement [ 7 , 36 – 38 ]. Most studies did not report any sensitivity assessment, except for one paper [ 35 ]. No studies conducted specificity analysis. Three of the papers which involved visual imaging included auditory perceptual analysis to validate the instrumental measures of voice onset used.

Regarding the GRADE Certainty Assessment, one study was rated as ‘moderate’, two as ‘low’, and 20 as ’very low’ certainty of evidence. The findings of this section prove that the use of equipment (namely laryngoscopy) can introduce further variance in voice onset measures used, with an extensive range of voice onset measures despite the similarities across the visual imaging hardware used.

Automated voice onset measures

In examining the 35 studies, an interesting theme which arose was the increasing use of task automation to obtain voice onset measures in recent years. For the purposes of this review, ‘automation’ refers to any process throughout a study’s methodology which uses a form of computerised software or algorithm to eliminate the manual need to prepare or process data. Only nine studies [ 24 – 27 , 29 , 37 , 51 , 57 , 60 ] were found to involve no automated processes. These studies generally involved a research question focused upon auditory perceptual judgements, reliability or fidelity checking, or presented a descriptive review of a specific voice onset measure based on previous literature, and as such did not involve the analysis of large sets of objective voice onset measurement data. There were four studies which only involved automation in the pre-processing phase [ 23 , 33 , 34 , 38 ], with most using an automated process for both pre-processing and/or voice onset data output. Three studies used automation for data output alone [ 28 , 32 , 49 ]. According to measurement category, those studies which fell within the visual imaging and acoustic categories mainly used automation for processing and data. Across the remaining categories of physiological, aerodynamic and auditory perceptual studies, the automated phases of data analysis tended to vary more greatly.

Across the 26 studies which used automated algorithms, 12 used solely proprietary software or programs to perform automated functions upon their datasets, nine used only customised algorithms or programs, three used a combination of either proprietary and custom software, or used proprietary software with customised algorithms or applications specific to the research project and two were unspecified/unclear. There were several proprietary tools used across multiple studies, with the most common being MATLAB, in seven papers. While certain algorithms and filters were also named and described across studies, a close examination of these is beyond the scope of this paper.

Research quality

The process of data extraction included extracting data pertaining to the conduction of reliability, sensitivity or specificity analysis in any of the 35 studies. It was found that fourteen of the 35 studies conducted some form of reliability analysis while one conducted some form of sensitivity or specificity analysis. According to measurement category, reliability analysis was most commonly conducted in auditory perceptual studies, with all auditory perceptual papers conducting some form of reliability analysis. Reliability analysis was also common in the acoustic and visual imaging categories, with just under 50% of papers in both categories reporting reliability ratings. While 25% of papers in the aerodynamic category involved reliability analysis, this was least common in the physiologic category, with only one of 11 papers reporting reliability. Sensitivity was reported in one paper, which was common to both the acoustic and visual imaging categories. Specificity analysis was not conducted in any measurement category.

Of the papers which included reliability checking, two performed exclusively intra-rater reliability, while seven solely performed inter-rater reliability analysis. Five papers examined both intra- and inter-rater reliability. For intra-rater reliability, the number of samples re-rated for the purposes of reliability ranged from 10% [ 24 , 35 ] through to 36% [ 50 ], with reliability agreement ranging from an ICC value of 0.341 (one rater with poor intra-rater reliability [ 24 ]) to an ICC value of 0.975 [ 12 ]. Of those studies examining inter-rater reliability agreement, the number of samples re-rated varied from 10% [ 35 ] to 100% [ 7 , 23 – 25 , 36 – 38 ]. Inter-rater reliability agreement ranged from an ICC value of 0.145 [ 24 ] to 0.998 [ 54 ].

The metrics used to assess both intra- and inter-rater reliability included the intraclass correlation coefficient [ 23 – 25 ], Pearson product-moment correlations and absolute difference [ 12 , 49 ], Pearson’s correlation coefficient [ 35 , 54 ] and Cohen’s kappa [ 25 , 33 ]. Cronbach’s alpha [ 50 ] was used to determine intra-rater reliability in a single study, while percentage agreement [ 7 , 37 , 38 ], the general linear model and repeated measures of analysis [ 35 ] and the Wald 99% confidence interval [ 34 ] were used only for inter-rater reliability calculations. It should be noted that percentage agreement, as used in Shiba and Chhetri, Freeman et al., Cooke et al. and Koike’s studies should not be used as a standalone statistical measure for inter-rater reliability assessment, as these percentages do not account for concurrence that can be expected by chance, and ultimately does not represent a robust means of determining reliability agreement [ 25 ].

Only one of the 35 included studies conducted sensitivity analysis, with no studies conducting an analysis on specificity. Kunduk [ 35 ] posed a research question specifically related to sensitivity, determining whether the timing characteristics, pattern of adduction, start of vocal fold vibration and number of cycles required for the vocal folds to reach full vibration were sensitive to aging, as measured by the VIP. It found that timing characteristics during the VIP were sensitive to the effects of aging, with all timing variables being higher in the older group (mean age 76 years) than the younger group (mean age 26 years). However, the only measure found to reach a significant difference between the younger (mean = 11 cycles) and older groups (mean = 14 cycles) was the number of vocal fold oscillatory cycles before full length vocal fold vibration was achieved (p = 0.001). Across the remaining 34 studies, a select few made a comment relating to sensitivity when interpreting their results [ 30 , 37 , 47 , 54 , 55 ], however no sensitivity analyses was completed.

While most studies did not report sensitivity nor specificity analysis, 18 of the 35 did seek to use their chosen measure/s of voice onset to differentiate between voice onset types. However, many of these provided an in-text description of what appeared to differ across voice onset types (e.g., how a particular waveform or kymograph varied between breathy and hard onsets), rather than offering numerical cut-off values.

Overall, while the abovementioned papers report reliability outcomes to be of an acceptable level across studies, and VIP to be a sensitive measure of voice onset in detecting age-related differences between patients for the number of vocal fold oscillatory cycles, collectively it is clear that most voice onset measures have not been studied to the level required to be certain of their reliability, sensitivity and specificity.

GRADE evaluation of research quality

All authors used the GRADE system to evaluate research quality. This evaluation was completed immediately following data extraction for each study. Across all papers, the certainty of evidence as evaluated by GRADE ranged from ‘very low’ to ‘moderate’, with 27 of 35 papers falling in the ‘very low’ category, seven papers classed as ‘low’ certainty and one as ‘moderate’. GRADE certainty assessment values were similarly low across all measurement categories, with the single study assessed as moderate evidence certainty being classed within the ‘visual imaging’ category.

Acoustic analysis studies ranged from very low to low, with 14 categorised as ‘very low’ and five as ‘low’ certainty of evidence. Those four studies exploring aerodynamic analysis were all classed as ‘very low’ certainty of evidence, as was the case for six of the auditory perceptual papers, with one being classed as ‘low’ evidence certainty. The eleven physiological papers ranged from ‘very low’ to ‘low’ evidence certainty, with eight being ‘very low’ and three falling in the ‘low’ certainty of evidence category. Visual imaging was the voice onset measurement category with the largest number of papers, ranging from ‘very low’ to ‘moderate’ certainty of evidence. Amongst these papers, 19 were rated as ’very low’, three as ‘low’ and a single paper was deemed to have ‘moderate’ certainty of evidence.

Summary of main findings

Across the 35 studies included in this systematic review, all methods of voice onset measurement examined could be classified into one of five categories: auditory perceptual, acoustic, aerodynamic, physiological measures and visual imaging. These studies were evaluated as showing low level of evidence, ranging from very low to moderate certainty of evidence according to the GRADE rating system. Collectively, we found that the reviewed literature presents high variability in vowel onset measures, methodology and automated processes applied, with a lack of robust, high-quality data for any given measure of vowel onset. The voice onset measure explored by the greatest number of studies was VAT, having been examined in seven studies with the highest quality paper reflecting a GRADE rating of low-quality evidence. The paper with the highest evidence rating according to the GRADE system was of moderate evidence certainty [ 49 ], with all other papers being rated as low or very low. Overall, none of the 35 papers in question present high quality research evidence, with a clear paucity of studies examining measures of voice onset in a clinical context. As such, the present literature findings prevent a conclusion of which measures of voice onset would yield the most reliable results with satisfactory sensitivity and specificity to be used in clinical practice.

Heterogeneity in dataset

The collective data preclude a conclusion pertaining to the most reliable, sensitive and specific measures of voice onset for a variety of reasons. Firstly, across the 35 papers, there is great heterogeneity in the study populations used. There is variability in sample size, ranging from 1 to 112 participants per study and in ages explored, with those studies which report the age of their participants extending from ages eight to 87 years. A further source of variability is the genders included across the studies, with those which report the gender of their participants having an exclusively female or male population or a combination of both. Furthermore, the inclusion of a control or dysphonic group within each paper varies greatly. While most papers only examined normophonic participants, seven involved either an exclusively voice-disordered population or a matched group of participants with voice disorders, with diagnoses ranging from neurological disorders (spasmodic dysphonia) to vocal hyperfunction (vocal nodules) and malignant conditions (laryngeal cancer). Collectively, this extensive scope of participant demographics in each study population prevents both the generalisation of these findings to a larger population and the ability to draw an informed and cohesive conclusion pertaining to the reliability, sensitivity and specificity of the voice onset measures explored.

A further source of heterogeneity across the studies is found in the measurement methods used, with studies exploring either auditory perceptual, acoustic, aerodynamic, physiological or visual imaging-based measurement types, or in 18 studies, a combination of these. Across the 35 studies there are 39 different measures of voice onset used. Even in the case of VAT, the most explored voice onset measure in the dataset, there is variability in how this measure is collected, with a difference in approach evident across research groups. This variance in measurement methods over time can be attributed to technological advances. Many vowel-initial measures of voice onset may never reach the stage of becoming clinically practicable as new measures, based on updated technology and approaches, are constantly being developed before existing measures are sufficiently researched and applied to clinical contexts of voice assessment.

The automation of processes throughout the methodology of studies introduces a further source of variation in the voice onset literature. Automation is applied throughout the dataset in the stages of data processing, data generation or a combination of the two, with 27 of the 35 studies using automation in some capacity throughout their methodology. With a vast variety of algorithms and software platforms employed across these studies and the differing stages where these automated processes are applied, it is evident that automation introduces furthermore heterogeneity of measurement across the vowel-initial voice onset literature.

There are several potential sources of this heterogeneity. Voice onset is a complicated measure, such that currently there appears to be no single measure able to quantify it satisfactorily. This may have led to ‘exploratory’ studies in the absence of a theoretical model of voice onset, which introduces variation in the way vowel onset is measured and explored. Other sources can be attributed to the array of robust research indicators which are presently lacking across the vowel onset evidence base. The current evidence lacks well-designed studies which include a pre-calculated sample size, random sampling of the study population, theoretical models and reliability, sensitivity and specificity ratings for outcome measures of interest, reasonable rationales for vocal tasks used, voice disorder classification criteria, focal voice disorder populations (i.e., currently there are mixed population groups, such as functional and organic voice disorder types) and standardised voice onset measurement protocols. This range of factors can likely be attributed to the extensive variation between each of the studies which make up the collective set.

This heterogeneity in turn, limits interpretation and generalisability of the presented data. Across the study set, limited and underestimated sample sizes are highly prevalent, with all studies lacking a pre-calculated sample size with sufficient statistical power. This limits the ability to meaningfully interpret any data and apply this to larger populations. The lack of standardised protocols and reliability analyses across the reviewed studies is another contributing factor, which results in issues with the data reported and difficulty in interpreting this. Finally, the inconsistencies in methodology, outcome measures, measurement techniques and results across studies make it exceedingly difficult to draw significant trends and conclusions.

Collectively, there is great variability in the measurement of the voice onset phenomenon from methodological approach through to selected voice onset measure, leading to a vast array of data that can’t easily be replicated, interpreted nor synthesised. This heterogeneity prevents us from ascertaining the clinical utility of each respective measure and as such, disallows us from forming any generalisations pertaining to clinically valid measures of vowel onset. The diversity in methods and approaches highlights the lack of a commonly accepted standard when performing voice onset analysis, which further limits the opportunity to appreciate how voice onset could best, most reliably, sensitively and specifically be applied in a clinical context.

Voice onset definitions

An added limitation of the study findings is grounded in the lack of accepted definitions pertaining to voice onset in vowel-initial contexts. While most studies provided some form of voice onset definition, there was considerable variation between these; with ten defining only the specific voice onset measure/s examined in their study and a further ten papers describing voice onset according to a clear and detailed definition which accounted for the range of physiological processes involved. Of the papers which did not specify the meaning of voice onset, these often reported providing instruction, training and/or modelling to study participants which is not detailed in each paper (for example, [ 36 ]). Training of subjects requires perceptual judgement of voice onset by trainers and speakers to perform the voice onset. Therefore, the lack of independent verification of perceptual features present in the samples where auditory perceptual ratings were not used is problematic. This lack of reporting also limits the opportunity for replicability and consistency between studies. Without the provision of clear and explicit definitions of vowel-initial voice onset across the literature, it is difficult to establish if the phenomenon being measured is in fact voice onset. Given that the definition of voice onset informs the methodology and nature of research conducted across each study, this discrepancy across the collective dataset is a clear contributing factor to the heterogeneity of study design and outcomes.

The issue of ambiguity surrounding what specifically is being measured as voice onset is further compounded by the lack of correlation with auditory perceptual judgements throughout the collective group. With only three of the papers correlating their instrumental measures of voice onset with a perceptual judgement of onset type, most papers are neglecting the gold standard of voice assessment and in so doing, bringing into question the validity of their chosen measures of vowel-initial voice onset.

Quality of evidence

The GRADE findings of this review evidenced that the quality of papers throughout the vowel-initial voice onset literature is low, informed largely by the research design and small sample size of all studies examined. Amongst these papers there was a low incidence of reliability assessments to ascertain the reproducibility of research findings, with some form of reliability assessment occurring in only 14 of the 35 papers. Across these papers, these ratings tended to be quite variable, including instances of low reliability reported. This may have resulted from factors pertaining to the raters themselves (i.e., variation in clinical experience, skill set and training in use of the measurement tool) but is most likely attributable to elements associated with research quality, such as study design, sample size and sampling methods. A cross-sectional study is typically less reliable than prospective or cohort studies, small sample sizes yield less reliable results than studies involving greater participant numbers and convenience sampling is generally less reliable than random sampling. With cross-sectional studies being the most common study design and the use of small sample sizes attained through convenience sampling across the 35 papers, the overall low quality of the collective paper set elucidates some causative factors behind the low and variable reliability results reported in this review.

Compared to reliability analysis, even lower rates of sensitivity assessment were performed with only a single study reporting some form of sensitivity analysis, and nil studies were found to analyse specificity. Almost none of the reviewed studies used voice onset measures to discriminate disordered from non-disordered speakers. Furthermore, voice onset measures were not used as an outcome to detect participants’ vocal condition. These factors help to account for the lack of discrimination analyses conducted across the studies.

Strengths and limitations

The papers included in the systematic review covered all types of relevant literature available at the time of the study, featuring a comprehensive search strategy including both published papers and grey literature sources. Updated searches were conducted in December 2022 and May 2023 to ensure all recently published articles of interest were considered for review. Limitations of the study approach include only examining literature published in the English language i.e., excluding non-English sources, and not performing a further citation search of the two studies added to the dataset from the final updated literature search, which may have potentially sourced further studies of relevance. A lack of quantitative data and a high level of heterogeneity between the studies prevented the conduction of a quantitative analysis of the collective study findings. The dearth of data conducted beyond a laboratory-based setting also made it difficult to determine which measures of voice onset may be most practical for application in clinical contexts. As such, we are unable to develop well-informed recommendations and conclusions pertaining to how voice onset may be most effectively measured in patient scenarios, as these conclusions would not be supported by research we would describe as reliable, sensitive nor specific.

Comparison with other studies

Nil other review studies have been conducted into vowel-initial voice onset measurement to enable a direct comparison with the existing literature, however, several studies have recognised that the existing pool of voice onset measurement literature presents a heterogeneous set of data and low level of evidence methodologies. For example, Patel [ 49 ] reported that studies investigating the onset of phonation examine small cohorts of vocally healthy adults and have utilised different waveform types, which yields variable findings. Likewise, Petermann and colleagues [ 62 ] recognised that the present literature involves different approaches to measuring even the same voice onset measure, with no standardised processes in place and wide inter- and intrasubject variability, which complicates the cross-study comparison of results. Maryn and Poncelet [ 24 ] also recognised the failings of the existing voice onset literature in examining or developing a range of quantitative, objective voice onset measures, without any application to clinical voice assessment protocols nor patient-centric contexts.

Clinical implications

The lack of an accepted standard pertaining to vowel-initial voice onset measurement in clinical contexts is directly evidenced in the range of clinical voice assessment proformas which lack an assessment of this feature. Despite the utility of vowel-initial voice onset in providing predictive information pertaining to the voice function that follows, the plethora of studies relating to vowel-initial voice onset measures have proved trivial in bridging the gap between theory and practice; failing to identify a single form of measurement which is proven to yield reliable, sensitive and specific results which can be applied to clinical voice patient contexts. Until such a measurement tool can be identified and researched to prove its utility as a clinically valid measure, it seems that clinical voice assessment and the standardisation of voice assessment tasks will continue to be limited by the current gaps in the voice onset literature.

Implications for research and future studies

Further, high quality research is clearly needed in the vowel-initial voice onset measurement space, preferably, within the next five to ten years. These papers would ideally involve a comparison of voice onset measures using methods of assessment which could easily and efficiently be applied in clinical contexts, as well as validation of these individual measures. In addition, further research into standardised measurement criteria and voice assessment protocols which incorporate clinically viable measures of vowel initial voice onset would prove valuable. Given that vowel-initial voice onset measures provide useful information for all voice disorder populations, diverse populations and disorder types would need to be considered. Performing effect size calculations which are clearly documented in the resulting manuscript, and seeking large study populations wherever possible should be prioritised.

Further research should also perform independent auditory perceptual ratings of samples for cross-comparison; ideally using publicly available voice databases wherever possible. It is also of utmost importance that future voice onset research presents a physiological definition of what precisely each study will measure, rather than measuring voice onset solely according to perceptual judgements of voice onset type. In the same vein, these studies must also ensure that the measure they select is able to assess these physiological features, rather than base a measurement upon inference. The development of such research would lead to far greater confidence in the collective findings across the vowel-initial voice onset literature, and an ability to develop informed recommendations pertaining to the application of these measures in a clinical capacity.

Voice onset is a highly variable event involving multiple physiological processes and as such, is a difficult phenomenon to measure. The findings of this review do not permit us to provide informed recommendations regarding the most reliable, sensitive and specific means of measuring vowel-initial voice onset, due to the heterogeneity and overall low research quality of the examined studies. There is a clear need for high-quality data and well-designed research which examines voicing control across the lifespan and across disorders. Ideally, this should compare a range of measures, particularly those which would be easily practicable in clinical scenarios, and provide a robust evaluation of their reliability, sensitivity and specificity in patient-based contexts.

Supporting information

S1 checklist. prisma 2020 checklist..

https://doi.org/10.1371/journal.pone.0301786.s001

S1 File. Systematic review protocol.

https://doi.org/10.1371/journal.pone.0301786.s002

S2 File. Database search strategy.

https://doi.org/10.1371/journal.pone.0301786.s003

S3 File. Data extraction summary table.

https://doi.org/10.1371/journal.pone.0301786.s004

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12+ Literature Review Outline Templates
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Introduction Literature Review
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Research Proposal: Introduction, Literature Review, and Methodology
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What is literature? An introduction to the study of literature| William Henry Hudson
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Scholarly Introductions and Literature Reviews
The introduction and the literature review of your paper have the same job. Both are supposed to justify the question (s) you are asking about your topic and to demonstrate to your audience that the thing you are writing about is interesting and of some importance. However, while they have the same job, they do it in two different ways.
LibGuides: Literature Reviews: Writing the Literature Review
A reference list at the end of a literature review is essential. Citing all sources gives credit to the authors of the literature, allows others to find the literature for evaluation or their own research, and helps to avoid plagiarism. For more information on creating a reference list, see our Citation Styles guide.
PDF Writing a Literature Review
A literature review should do at least four things, the first three of which are related. • First, it should analyze critically a body of research. To analyze critically does not mean to point out what is wrong or flawed about other studies or to simply report what other studies say or do. Rather, it means to identify and perhaps briefly ...
Introduction
The literature review is a vital part of the argument the author makes in support of a thesis. The literature review offers brief descriptions, summaries, and critical evaluations of each work, and does so in the form of a well-organized essay. The goal is to summarize, synthesize, and critique arguments and ideas of others, and point to gaps ...
Write a Literature Review
1. Introduction. Not to be confused with a book review, a literature review surveys scholarly articles, books and other sources (e.g. dissertations, conference proceedings) relevant to a particular issue, area of research, or theory, providing a description, summary, and critical evaluation of each work. The purpose is to offer an overview of significant literature published on a topic.
The Literature Review: 1. Introduction
Second, a literature review seeks to describe, summarize, evaluate, clarify and/or interrogate the content of primary reports." (Cooper, 1998, p. 7) "A literature review is a written document that presents a logically argued case founded on a comprehensive understanding of the current state of knowledge about a topic of study.
Getting Started
A literature review may constitute an essential chapter of a thesis or dissertation, or may be a self-contained review of writings on a subject. In either case, its purpose is to: Place each work in the context of its contribution to the understanding of the subject under review. Describe the relationship of each work to the others under ...
Why Do A Literature Review?
Literature review is approached as a process of engaging with the discourse of scholarly communities that will help graduate researchers refine, define, and express their own scholarly vision and voice. This orientation on research as an exploratory practice, rather than merely a series of predetermined steps in a systematic method, allows the ...
Literature Review Guide
A literature review explores all sides of the research topic and evaluates all positions and conclusions achieved through the scientific research process even though some conclusions may conflict partially or completely. From the Online Library. Conducting Your Literature Review by Susanne Hempel. ISBN: 9781433830921.
Definition
Literature Review: Definition and Example. A Literature Review is "a systematic, explicit, and reproducible method for identifying, evaluating, and synthesizing the existing body of completed and recorded work produced by researchers, scholars, and practitioners." - From Conducting Research Literature Reviews: From Internet to Paper, by Arlene ...
PDF LITERATURE REVIEWS
1. EXPLAIN KEY TERMS & CONCEPTS ¡ examine your research questions: do they contain any terms that need to be explained?(e.g. identity, discourse, culture, ideology, gender, narrative, collective memory) ¡ be aware that key definitions and background should be provided in the introduction to orient your reader to the topic. the literature review is the place to provide more extended ...
Writing Literature Reviews
In this chapter, you'll learn the steps to creating a literature review including. writing an introduction, body paragraphs, a discussion/conclusion, abstract, and other elements. drafting and getting feedback. revising your literature review. Note: Because this chapter involves the steps for writing your Literature Review, the discussion ...
PDF Systematic Literature Reviews: an Introduction
Compared to traditional literature overviews, which often leave a lot to the expertise of the authors, SRs treat the literature review process like a scientific process, and apply concepts of empirical research in order to make the review process more transparent and replicable and to reduce the possibility of bias.
Thematic Analysis Literature Review
Unlike traditional literature reviews, which may adopt a chronological approach or focus on individual studies, a thematic literature review emphasizes the aggregation of findings through key themes and thematic connections. This introduction sets the stage for a detailed examination of what constitutes a thematic literature review, its ...
PDF Results Section for Research Papers
First, begin with an introduction to connect the results with the research question(s). This brings the readers' focus back to the purpose of the study after reading the literature review and methods sections of your paper. Second, present your findings in a structured way (such as thematically or
Introduction and Literature Review
This chapter contains a brief introduction to renewable energy and its advantages, especially solar energy. Also, contains surveying of CSP system technologies and presents a literature review for cost of solar energy, CSP modeling, and the application of ANN technologies in various SF systems.
Should definition of terms section be included in the introduction or
I have seen theses having it in the introduction while others in literature review chapter discussing each term in detail. Example of a thesis discussing definitions in the literature review chapter: Contesting the Culture of the Doctoral Degree: Candidates' Experiences of Three Doctoral Degrees in the School of Education, RMIT University. Link.
Exploring Social Media as an Information Source in IL Instruction
Introduction. In today's world, information moves fast, circulated by digital technologies such as social media. ... a 2021 literature review examining students' preferences on reading formats and the use of social media information sources for academic and non-academic purposes noted that college students use social media for "class ...
The applications of Australian-coded ICD-10 and ICD-10-AM data in
The authors were optimistic that the future introduction of ICD-11, which has substantially more codes, may help to ameliorate this problem. ... A scoping review of the literature was conducted drawing upon the five-stage framework for scoping studies as constructed by Arksey and O'Malley (2005) ...
Vowel onset measures and their reliability, sensitivity and specificity
Introduction. Measures of voicing control provide critical insight into a myriad of voice diagnoses across the lifespan. Voice disorders are highly prevalent, ... The scope of this literature review was the onset of vowel phonation without a preceding consonant. Studies and unpublished works were included if they were written in English ...
Nongestational ovarian choriocarcinoma with bilateral teratoma: A rare
The present case and our literature review also highlighted that fertility-sparing surgery and multidrug chemotherapy are effective methods for treating NGCO. ... laparoscopy, nongestational, ovary, teratoma. 1. Introduction. Ovarian choriocarcinomas can be divided into 2 types based on origin. The first type can result from ectopic ovarian ...
Successful surgical management of giant mucinous cystic ...
Introduction. Mucinous cystic neoplasm of the liver (MCN-L) are rare cystic liver tumors comprising of less than 5% of symptomatic cystic liver lesions [1].These lesions were previously termed as hepatic cystadenoma or cystadenocarcinoma before being reclassified as MCN-L according to World Health Organization (WHO) classification in 2010 [2].MCN-Ls are usually found in middle aged females and ...
Gels
This review focuses on the use of conventional gel or coil and "new" generation hydrogel used as an embolic agent in endovascular applications. In general, embolic agents have deep or multidistrict vascular penetration properties as they ensure complete occlusion of vessels by exploiting the patient's coagulation system, which recognises them as substances foreign to the body, thus ...