You will encounter many types of articles and it is important to distinguish between these different categories of scholarly literature. Keep in mind the following definitions.
PRIMARY RESEARCH ARTICLE: A primary research article describes an empirical study that aims to gain new knowledge on a topic through direct or indirect observation and research. These include quantitative or qualitative data and analysis. In science, a primary article will often include the following sections: Abstract, Introduction, Methods, Results, and Discussion.
REVIEW ARTICLE: In the scientific literature, this is a type of article that provides a synthesis of existing research on a particular topic. These are useful when you want to get an idea of a body of research that you are not yet familiar with.
PEER-REVIEWED: Refers to articles that have undergone a rigorous review process by peers in their discipline, often including revisions to the original manuscript, before publication in a scholarly journal. Primary research articles in reputable psychology journals are always peer-reviewed. Reviews are often peer-reviewed as well.
PREPRINTS: Preprints are an increasingly common publication type. Preprints have not gone through peer-review and are published on publicly accessible pre-print servers. They serve as a way for authors to get their work out quickly to the public and other researchers. They can go on to be published in scholarly journals with a peer-review process.
Getting too many or too few search results? Use Boolean operators to narrow or widen a search. For example, Dog AND Cat will narrow your search to only include results that include both of those words. The OR operator will broaden your search. The NOT operator can sometimes filter out too many articles so use it cautiously.
Research databases are key to conducting comprehensive or specific searches of the scholarly literature across many different publishers and journals. They include special tools and filters to help you narrow and expand your search. Many databases, such as Web of Science, have more advanced search tools than Google Scholar and will allow one to more efficiently find the literature that they are looking for.
This thesaurus is an example of a controlled vocabulary. A controlled vocabulary is a list of standardized terms used by catalogers and database indexers to describe what an article or book is about. APA staff manually tag each article with a handful of index terms. This allows for very precise and comprehensive searching. The word "depression" for example has many synonyms that you might miss with a simple keyword search, but if you search with the index term of depression, you will be able to find every article on that topic, whether the article uses the word "depression," "melancholia," or "sadness" for example. The major concepts contain many narrower concepts. Check the Explode box to include the narrower concepts in your search. Here we are adding the concepts of "major depression" and "bullying".