Mechanisms of Intelligence

Mechanisms of Intelligence

1. Heritability

   • Galton - tried to separate genetic/envrionmental influences
   • Assessment
     • Family
       • Parent/child associations
     • Twin
       • MZ IQ .85 (reared apart .75) DZ IQ .6 Different environments/treatments
     • Adoption
   • Considerations
   • Family Environment
     • Shared/non shared
     • Within family
       • Passive Child effects Parent effects
     • Outside family

2. Stability

   • IQ more similar at similar ages
   • Gene linkage
     • Estimate quality of IQ prediction from genes - genetics account for 24% of intelligence change from childhood to old age
   • Gene for x..
     • Where x differs between individuals with two alleles
     • Causal chain of genes

3. Increases: Flynn effect

   • 100 on 1972 = 108 on 1948
   • Environment
     • Generation to generation - cannot be natural selection so must be envrionment
   • Family size
     • Younger children of larger families have lower IQ 1. First child gets all attention - then cognitive demands of helping younger siblings and resources have to be spread more thinly 2. Adults with low IQ have more children 3. Larger families spend more time with children because there are less adults
   • Nutrition
     • Increased fruit, veg, fIsh = better nourished = increased IQ
     • Breastfeeding - better vocab than no breastfeeding May just be related to mother's intelligence
     • Multivitamins - only help when would otherwise have been malnourished
   • Maternal health
     • Smoking = Low birth weight and lower IQ at 18
     • Alcohol = FAS = reduced intellgence and memory problems
   • Education
     • -Longer compulsory education = increased verbal intelligence -School and intelligence influence each other -Fewer apprenticeships mean school is now only option so we are better educated -Interactive teaching and educational TV shows
   • SES
     • Low SES = larger family, less healthy food, less healthcare - but parents probably had low SES when growing up 
     • National Child Development Survey 7 to 33 Class I had 10 more IQ points than class V

4. Interventions

   • Head Start