Intelligence and Aptitude
This section tests theories of intelligence, IQ computation, and the properties of good tests. Expect formula-based numerical items and evaluation of Gardner and Sternberg against psychometric evidence.
Theories
- Spearman: general factor g plus specific factors s.
- Thurstone: seven primary mental abilities.
- Gardner: multiple intelligences (linguistic, logical-mathematical, spatial, musical, bodily-kinaesthetic, interpersonal, intrapersonal, naturalistic).
- Sternberg: analytical, creative and practical intelligence.
- Cattell-Horn: fluid (Gf) and crystallised (Gc) intelligence; the CHC model integrates them.
Measurement
- Ratio IQ = (mental age divided by chronological age) multiplied by 100.
- Deviation IQ: mean 100, standard deviation 15 (Wechsler scales).
- Aptitude tests predict future potential; achievement tests measure learning already acquired.
- Test quality: reliability, validity, standardisation and norms.
Worked example
A 10-year-old has a mental age of 12. Reasoning: IQ = (12 divided by 10) multiplied by 100 = 120. This is above average but below the usual gifted cutoff of about 130.
Traps
- Gardner's intelligences are not one psychometric g.
- IQ 100 is average, not the maximum.
- Reliability is consistency; validity is accuracy of measurement.
- Aptitude and achievement tests are not interchangeable.