Psychology is the study of behavior. Behavior can be assessed through observation as well as psychological tests. Test results provide a sampling of a person's characteristics or traits. As such, they can be used to help predict future behavior. Some psychological tests are also capable of uncovering psychiatric symptoms. Although results may suggest the existence of a psychiatric condition, definitive conclusions regarding mental health diagnoses are unable to be made on test results alone.
Intelligence tests are used to measure a person's overall level of intellectual functioning. In his book "Psychological Testing", psychiatrist Robert J. Gregory states that despite the varying definitions of intelligence, experts tend to agree that it includes the capacity to learn from experiences and adapt to one's surroundings. The Stanford-Binet Intelligence Scales is a popular intelligence test. It can be administered from age 2 through late adulthood and assesses reasoning, visual-spatial processing, knowledge and working memory. Other commonly used intelligence tests include the Wechsler Intelligence Scale for Children-III (WISC-III) and the Cognitive Assessment System (CAS).
Personality tests are self-reported inventories that are used to assess personal traits and behaviors. The most widely used personality inventory is the Minnesota Multiphasic Personality Inventory. The MMPI-2 consists of 567 true-or-false questions and takes over an hour to complete. It touches on a variety of topics such as health concerns, relationship problems, substance abuse, self-esteem, anxiety, depression, manic symptoms, delusions and hallucinations. The MMPI-2-RF is a shorter version with 338 questions. The Myers-Briggs Type Indicator (MBTI) is another common test used to categorize people into personality types based on four realms of psychological functioning.
Projective testing is rooted in the psychoanalytic theory. It is based on the belief that one's wants, needs, motivations and instincts are unconscious constructs. In order to reveal one's innermost thoughts, individuals are shown ambiguous stimuli and asked to explain what they see. For example, the ambiguous stimuli used in the Rorschach test are 10 symmetrical inkblots. The Thematic Apperception Test (TAT) is another commonly used projective test. What is construed from these tests is prone to subjectivity. Therefore, interpretations typically vary among examiners.
Interest inventories are often given to high school and college students by guidance counselors to assist students in identifying occupational preferences and determining career paths. One of the most widely used interest inventories is the Strong Interest Inventory (SII). The SII asks students whether they like or dislike certain school subjects, recreational activities and types of work. It also assesses personality types to determine which of six work environments best suits them. The six occupational types are realistic, investigative, artistic, social, enterprising and conventional.