There are three parts to conducting a literature review - searching, evaluating, and writing. Use the links to explore each part. 
Comprehensively Search the Literature: Find the scholarly conversation on your topic and becoming an expert on your particular research question
Review Articles: Evaluate the sources you found to determine the best to include, which may also be called an annotation, article review, article critique, or article analysis
Write the Literature Review; Synthesize and analyze the sources you found for your audience, using them to demonstrate why your study is important, and joining the scholarly conversation.
The purpose of the literature review in your research proposal is to explain the importance of your study to the audience and provide the background of how your research question has been studied in the past. In essence, with your study you are joining the scholarly conversation on your research question and moving the field of psychology's knowledge further.
Incorrect source identification is a common area for missing points on psychology assignments at Xavier. Knowing how to identify source types at a glance:
Review each tab to learn psychology source types
These are the fundamental sources in psychology. You can use them for answering a research question, determining a gap in the research, or finding a methodology to emulate.
Research studies report experiments conducted by psychology researchers. They are primary sources in psychology that other sources, such as meta-analyses or commentaries, will analyze. Research studies are the bread and butter of a literature search, and they should make up the majority of the references in your literature review. However, they can be difficult to understand.
Research studies are written to the audience of other psychology researchers and assume you already know the terminology and history of the scholarly conversation in their area of research. You may need to rely on other sources in psychology, such as meta-analyses and reference sources, to learn the definitions and background information you need to understand the research study. That's to be expected in undergraduate and grad school level research.
When you're conducting your own research study, a test or measure is what you need.
According to APA, “Psychological tests, also known as psychometric tests, are standardized instruments that are used to measure behavior or mental attributes. These attributes may include attitudes, emotional functioning, intelligence and cognitive abilities, aptitude, values, interests, personality characteristics, and more. Psychological tests may also be used to evaluate mental health, such as psychological functioning or signs of psychological or neurological disorders. Psychological tests are used in research labs, workplaces, schools, and other settings."
However, the complete test or measure used in a research study is not always disclosed in the research study itself. Ethical use of tests and measures is of high importance for the field of psychology. Some would become invalid if the information got out to the general public or became available through Google. Others require significant knowledge and training to administer and score in a way that maintains the integrity of the test. The authors spend a great deal of intellectual effort and time to create and validate the tests, so it is only fair (and legal) to respect how the authors and publishers want their work to be used. Tests and measures are sometimes available in specific databases with directions for how they can be used. Others, you may need to ask the author for access to the test.
For the purposes of your assignments in college, you will be collecting the data rather than searching for it as an outside source.
Data is the raw information gathered during research, which can be quantitative (numerical) or qualitative (word-based). Some examples include answers to tests or measures, survey results, brain scans, demographic information, or interview transcripts. Once gathered, researchers will compile, analyze, and interpret the data. Data is considered a primary source in psychology because it is the raw material you or researchers are analyzing.
In many cases, unless you are the researcher conducting the test or you are using a published data set, the raw data will not be available to you. Research articles often show summaries of gathered data in tables or graphs, but the individual answers to surveys, interviews, or other data will not be provided. However, when you conduct your own research study, all the answers to surveys, tests, or measures will be the sources that make up your data set.
Best for an overview or history of a research topic, finding the scholarly conversation, discovering primary research studies, and identifying gaps in the research.
Review articles look at all the research studies conducted research in a specific area, summarize it, analyze it, and draw conclusions based on the evidence. They are secondary sources, meaning they analyze primary research studies. It’s one thing if you have a single study showing a correlation, it’s another if you have 50 studies across several populations that all show the same results. Or maybe the results are mixed. A review will determine whether the conclusion of a study was a single case or whether it has been repeated enough to show a pattern.
Many primary research studies are difficult to understand without knowing the context and definition of terms. Meta-analyses provide the context and definitions, usually in easier to understand language than research studies. These reviews are a great place to start your literature search because they give you the big picture and provide the background knowledge you need to understand primary research studies. They also outline gaps in the research that can give you ideas for your own original research questions. Finally, the references listed can help you identify primary research studies to explore in more depth.
Meta-analyses look backwards in the scholarly conversation and take significant time to compile, which means they aren't the newest contributions. Be sure to search for research studies conducted since the review to ensure you're up to date on the current scholarly conversation. Someone may have closed the research gap mentioned in the article.
When you're choosing the best methodology or need models for analyzing a research study, commentaries are the way to go.
Commentaries, editorials, and opinions are typically written by a single, author or several, providing critique of a research study or meta-analysis. They point out gaps in the research, potential issues or blind spots with the methodology, or disagreements with the conclusions drawn from the results. They may also be a call to action or further study. Study authors may reply to theses comments in the journal as well. The opinion articles and their replies do not go through the peer-review process.
You are asked to engage with research studies at a similar level of analysis to these commentaries. It can be helpful to see how researchers are analyzing research studies as you grow your analysis skills in your assignments and papers. Commentaries and editorials can also be helpful when choosing the best methodology for your own research study. The critiques given or the author's replies may provide the key to whether you use a certain test/measure or help you choose between several.
If you need a high-level overview or the definition of difficult terms, reference sources are the place to go.
Reference sources provide definitions of terms and top-level overviews of topics in psychology. They include encyclopedias, dictionaries, manuals, handbooks, directories, and some books. They are called reference sources because you refer to them for specific information rather than reading them cover to cover. The DSMV is one example of a reference source in psychology. Entries in reference sources often have no author because it is considered knowledge no one specific person can take credit for or because the information found in it is considered common knowledge in that field.
Reference sources can be your best friend when it comes to understanding the complex, subject-specific terminology found in research studies or meta-analyses. They are worth the time of finding if you're having trouble analyzing research studies for your assignments and papers.
When you need a short, top-level explanation of research topic or its applied importance to society, consult news or media.
News articles, magazines, blog posts, and social media get the word out to the general public about research studies or psychology topics. These are what you'll find with a typical Google search. They are written for a general audience, or occasionally as casual information keeping psychology professionals up to date. Though some may be written by researchers in professional organizations, they are often written by journalists or non-research focused psychology professionals.
News and media are secondary sources that are easy to understand but don't provide much depth or detail, which is why they aren't usually accepted as sources in college-level research papers. However, they can be useful as stepping stones to understanding more complex research studies or as a way to discover research you're interested in. You'll want to track down the original research study the blog is reporting on in the library databases or Google Scholar to get to the information to use in your assignments.
When you're doing an exhaustive search of the research that has been conducted on a topic, usually for graduate work, dissertations are a valuable asset.
Doctoral candidates are required to contribute original research to the field of psychology to receive their degree. Dissertations are the published reports of that research. To prove that their research is original, they must conduct an exhaustive literature review, The topics also tend to be highly specialized in order to contribute something new. Because of these factors, dissertations are very long, often a hundred pages or more.
Some schools publish their students' dissertations; however others are only found in expensive databases. Due to their length and relative difficulty to find, dissertations are often not a feasible option for college level research papers. The idea is that you're reading your sources deeply, and in full, and analyzing them for your own research. That's difficult to do with sheer length and complexity of dissertations. Many professors do not accept them as sources except at the doctoral level or require permission to use them in your papers.
Since dissertations are included in many psychology databases, it's important to be able to identify them. Then you can make a decision about including them or not based on your professor's instructions and the amount of time you have spend on a literature search.