When a scholarly article is submitted to a journal, it goes through a process called peer review. The editor of the journal will send the article to two or more experts in the field. They will carefully examine the article, including the research methods used and the conclusions the author draws, and they may return the article to the author for clarification and revision. Many of the library's databases, including Primo, allow you to limit your search to peer-reviewed articles only.
If you search using Google Scholar, be sure to change the settings to include full text materials from Simpson Library.