A personality test is a test that measures different aspects of a person's psychological traits and behavior, particularly those that remain relatively unchanged throughout a lifetime. They can measure patterns of behavior, thoughts and feelings. They are often used in the workforce to evaluate potential employees in terms of skills, intelligence and integrity, and to identify different learning styles. Developed by psychologists, the tests are scored and then compared with norms or averages for a specific group.

There are many different types of personality test. Some are projective tests that use unconscious projections of attitude on ambiguous situations. These include the famous Rorschach Inkblot Test or the Thematic Apperception Test. The former assesses a person's reaction to inkblots while the latter uses pictures as a basis for the client to make up a story. The development of the tests are usually theoretical or statistical and are refined over time.

Other tests use questionnaires that have a much higher level of standardization than the projective tests. The Minnesota Multiphasic Personality Test was created in 1942, and its most recent revision in the early '90s is one of the most widely used personality tests. The very first personality test was used in 1919 and coincided with the emerging science of psychology. Called the Woodworth Personal Data Sheet, it was used by the United States Army on new recruits in order to determine whether they were likely to suffer from battle fatigue.

The widespread use of personality tests in the workplace has come under criticism as some experts feel too much weight can be placed on the results of the tests. There are hundreds of tests available, but not all of them are psychologically sound or valid personality tests. People are complex beings, and the reduction of their characters to a series of "yes, no or maybe" questions has led some to doubt the usefulness of personality tests.

The popularity of personality tests in non-clinical settings can be explained to some extent by the Forer effect. This is when very vague or generalized statements are taken as precise and personal. For example, a test may come back with an analysis like "you can be self-critical" or "sometimes you feel you have not made the right decisions." These kind of statements are accurate for everyone at some stage of life, but because people want to believe the analysis, they take the information as personal and specific.