There are many forms of psychological tests, all of which offer both advantages and disadvantages. Perhaps the most common form of test is a self-report questionnaire, in which a subject answers a series of questions that gives information about one or more psychological traits. These tests are quick and easy to develop, to administer, and to score, but they are limited by the likelihood of inaccuracies in the subject’s self report.

Clinician-administered questionnaires allow the clinician to make the final scoring decision based on the subject’s responses to each question.

Interviews, like questionnaires, involve a series of questions administered to the subject, but the interviewer has room to follow up each question with probes to obtain more information or clarify responses.

Projective tests, like the TAT or the Rorschach, ask the subject to complete a task (e.g., to tell a story based on a picture), which is intended to reveal characteristic ways of thinking, feeling, and behaving. The subject, however, is unaware of the information being revealed.

In cognitive tests, the subject completes various tasks that involve intellectual skills, like memorizing a list of words or arranging blocks to match a pattern.

Sensory or motor tasks likewise measure sensory skills, such as sensitivity to touch, or motor skills such as visual-motor coordination.

Tests in these last three categories are often called objective tests because they involve the assessment of objective behavior.