Psych: Measuring Personality

Reliability

Consistency: do you get the same result if you take it again next month?

Validity

Accuracy: does it measure what it claims, and predict real behavior?

Multimethod

Combine interviews, tests, observation, and reports from others. Never rely on one score.

Cultural competence

Interpret scores in cultural context. Healthy cultural mistrust is not the same as paranoia.

Why assess?

to guide therapy, in legal cases (custody, competency to stand trial), and in hiring, where the stakes for fairness are high.

MMPI

Created at the University of Minnesota

MMPI-2

567 true/false items; 10 clinical scales

MMPI-3

335 true/false items, 52 scales, including validity scales, 25–50 minutes; ages 18+, First new norms since the 1980s, 1,620 adults matched to the 2020 census (12.4% Black). Validity scales catch "faking good," "faking bad," and random answering.

Rorschach inkblots

10 symmetrical inkblots (1921). "What do you see? What made you see it?" Newer R-PAS scoring (2011) improved norms

Thematic Apperception Test

Tell a story about an ambiguous picture. What led up to it? What happens next? Not standardized; scoring varies widely

Trade-off of projective tests

ower reliability and validity than objective tests, but harder to fake because there's no obvious "right" answer.

The Barnum effect

we accept vague, flattering descriptions as uniquely true of us. In Forer's 1949 study, students rated the same generic description about 4.3 out of 5 for accuracy.