intelligence change

intelligence change

1. stability

   • stability from childhood
     • Infant/ young children IQ measures not very stable over time ×  Relatively stable from age of 8-10 (McCall, 1977)
     • For Stanford-Binet and Wechsler tests, one-year test-retest correlations average around r = .90.
     • Different rates of development
     • Short attention span
     • Kangas & Bradway, 1971: age 4-42 corr. 0.41
     • Thereafter intelligence stable over time e.g., Jones & Bailey (1941) age 6- 18, r=.77; age 12-18, r=.89; 18-40, r>.7
   • over 66 years
     • Deary et al’s (2000) research shows mental ability stays quite stable over 70 years
     • All Scottish children born in 1921 took a validated test of psychometric intelligence on 1/06/1932 (N=87,498), Followed up 101 of them at age 77, correlation between scores at age 11 and 77 was ~0.8 (corrected) ×  Shows substantial stability, But also substantial change

2. IQ increase

   • IQ has a heritable component
   • Evidence from adoption studies shows improved environment associated with increases in IQ
   • Compensatory Education
     • head star attempted to break poverty, advantaged children got a head start, disadvantaged children started late and hence were doomed to fail. no evidence for long term effects on IQ
     • Interventions have been shown: - to improve test scores in the short-term - not to improve test scores in the long-term - to change other aspects of educational experience
     • substantial initial gains in IQ (>15 points) - vanished within 3-4 years of the end of the programme - 10 other similar programmes produced similar results
     • critics
       • programmes simply too short
       • 3 months to 5 years, 5 days a week §  showed longer-term gains in IQ (10 points -> age 12) §  but no impact on attainment
       • Abecedarian Project (Ramey & Campbell, 1984; Campbell et al, 2002) §  Individualised educational activities §  Began in infancy for 5 years §  Initially comparable in IQ to control group §  From 18 months, and at 12, 15, and 21 years had higher average Iqs (~5 points) §  Other effects: language skills, better maths achievement, etc.