Individual Differences and Intelligence
Intelligence is the capacity to understand, reason and adapt; the exam tests theories, IQ computation, test quality and the nature-nurture debate.
Theories
Spearman: general factor g plus specific s. Thurstone: primary mental abilities. Gardner: multiple intelligences (linguistic, logical-mathematical, spatial, musical, bodily-kinaesthetic, interpersonal, intrapersonal, naturalistic). Sternberg's triarchic theory: componential, experiential, contextual. Cattell-Horn: fluid (novel reasoning, declines with age) versus crystallised (knowledge, grows). PASS model: planning, attention, simultaneous, successive. Emotional intelligence: perceiving, understanding and managing emotions.
Measurement
Ratio IQ = (mental age divided by chronological age) x 100; deviation IQ compares a score with age norms (mean 100, SD 15 on Wechsler scales). Binet-Simon, Stanford-Binet, Wechsler scales and Raven's matrices. A good test is standardised, reliable, valid and has norms.
Extremes and issues
Giftedness (IQ about 130 and above); intellectual disability (IQ about 70 or below with adaptive limitations). Culture-fair testing, heritability and stereotype threat matter.
Worked example
A 10-year-old with a mental age of 12: IQ = 12/10 x 100 = 120. Reasoning: ratio IQ uses mental age, so it suits children; adults are scored by deviation IQ.
Traps
- Using ratio IQ for adults.
- Treating Gardner's intelligences as psychometric factors.
- Confusing reliability and validity.
- Reading heritability as meaning traits are fixed by genes.