Personality tests are methods for assessing human personality, though most rely on subjective self-report questionnaires highly susceptible to motivational and response distortion. While early attempts included 18th-century phrenology, modern assessment began in the 1920s for personnel selection, with Sir Francis Galton and Raymond Cattell contributing significantly to instruments like the Sixteen Personality Factor Questionnaire (16PF).
Noteworthy tests include the Minnesota Multiphasic Personality Inventory (MMPI) and the Revised NEO Personality Inventory (based on the Five Factor Model), though popular options like the Myers–Briggs Type Indicator (MBTI) have known psychometric deficiencies. The U.S. personality assessment industry was valued at an estimated $2-4 billion annually by 2013. These tests are widely used in various contexts, from individual and career counseling to clinical psychology and employment testing.