Individual Differences and Personality
Individual differences questions test intelligence theories, IQ computation, personality models and assessment methods.
Intelligence
Spearman proposed a general factor, g. Thurstone listed primary mental abilities; Gardner proposed multiple intelligences; Sternberg's triarchic theory includes analytical, creative and practical intelligence. Stern's IQ is mental age divided by chronological age, multiplied by 100. Wechsler's deviation IQ has a mean of 100 and standard deviation of 15. Aptitude predicts potential; achievement measures what has been learned.
Personality
Freud's psychodynamic theory divides personality into id, ego and superego and proposes psychosexual stages. Trait theories: Allport's cardinal, central and secondary traits; Cattell's 16PF; Eysenck's extraversion, neuroticism and psychoticism; the Big Five (openness, conscientiousness, extraversion, agreeableness, neuroticism). Rogers emphasised self-concept; Bandura's social-cognitive theory emphasises reciprocal determinism and self-efficacy.
Assessment
Methods include interviews, observation, rating scales, self-report inventories (MMPI, 16PF) and projective tests (TAT, Rorschach). Reliability is consistency; validity is whether a test measures what it claims.
Worked example
A 12-year-old with a mental age of 15 has IQ = (15 ÷ 12) × 100 = 125. Reasoning: this is above the average of 100, roughly 1.7 standard deviations above the mean. The score describes current performance; it is not a fixed label or an achievement score.
Traps
- IQ is not the same as achievement or aptitude.
- Projective tests are generally less reliable and valid than objective inventories.
- The Big Five is not identical to Eysenck's three dimensions.