Use Library Databases to find peer-reviewed journal articles. Not all databases include peer-reviewed journals. These are the best ones for psychology:
Academic Search Complete
This is an excellent database for all kinds of college research. It includes magazine and peer-reviewed journal articles. You can also use the search box to the right.
Includes the social sciences, like psychology, as well as the physical sciences. Includes scholarly book chapters as well as journals. Look for citations with the note "Original Research Article." A green box to the right of the citation indicates you have access to the full text (complete article).