Psych 322/Psych 110 Prof. Anagnostaras

1. Psych 322/Psych 110 Prof. Anagnostaras Intelligence and Exceptional Ability

2. What is intelligence? Spearman g factor - general intelligence - general mental ability to learn and develop adaptive behaviors - common ability to do well on all sorts of mental tests s factors - specific intelligence - specific knowledge and abilities when performing specific tasks Terman - Stanford-Binet intelligence test (IQ) Groups into 4 cognitive abilities: verbal reasoning, spatial reasoning speed of processing, and memory Wechsler - eliminated age effects (WISC, WAIS)

3. Actual Distribution of IQ Predicted Mean = 100 sd = 15 Many studies of genetic origins of low IQ, but not high IQ PKU RS DS WS FRX LNS DMD NF1 XXX, XXY AS, PWS XYY XO 50 70 85 100 115 130 145 Anastasi & Urbina, 1997; Plomin et al., 1999 >150 Genius +4 IGF2 promotor PM

4. Gene – Environment Interaction Nature – Nurture

5. Bouchard & McGue (1981)

6. Issue of Nature vs. Nuture Plomin et al. (1990) make the following estimates: .50 • Nature (Heritability) • Within family (Shared) .25 • Between families (Nonshared) .15 .10 • Error Plomin, R., DeFries, J., & McClearn, S. (1990).

7. What are Heritability, SharedEnvironment, andUnsharedEnvironment • Heritabilityis the proportion of variance in phenotypic expression of a trait in a given population that is attributable to genetic variation among individuals within that population • Shared environmentproportion due to environmental effects shared by family members (home, socioeconomic status, education) • Nonshared environmentproportion due to environmental effects unique to individual (illness, brain damage, experiences)

8. Twin Studies Estimate Heritability = 2 x (corr for MZ-DZ) N. Andreason

9. Thompson et al., Nature Neuroscience, 2001 Brain structure h > 0.9, certain features = 0.98

10. Thompson et al., Nature Neuroscience, 2001 Correlation of frontal grey matter volume with g, r=.37-.45

11. Nature v. Nurture Across lifespan: • impact of genetics increases from 40 to 60% •impact of shared environment decreases to 0

12. Heritability of Specific Cognitive Abilities correlation Ability studies MZ DZ Verbal compreh 27 .78 .59 Reasoning 16 .74 .50 Spatial 31 .64 .41 Perceptual Spd 15 .70 .47 Memory 16 .52 .36 Heritability (% variability due to genetic influence) Verbal .57-.58 Spatial .46-.71 Speed .53-.58 Memory .38-.43

13. Example of subtle nonshared environment In these identical twins, the orthodontist used a European technique on the twin on the right, which preserves a broader smile, whereas the twin on the left had a conventional American treatment

14. Adoption Studies

15. What about animals? Testing heritability by selective breeding

16. Tolman & Tryon: Selective breeding of maze bright and maze dull rats

17. Selective breeding of rat maze performance

18. Pitfalls of Tolman & Tryon's work • Hybrid crosses revealed due to multiple genes • No way to identify genes involved • Problems with what behavior was selected for (e.g., anxiety) • Seymour Benzer's work in drosophila fear conditioning really took off because crosses testing showed only a few genes involved • Hostility of the learning field toward genetics and individual differences was HUGE even though individual differences are HUGE

19. Selective breeding for high contextual freezing

20. Building a better mouse: Tang & Tsien’s Doogie

21. Enhanced Hipp LTP Transgene to overexpress NR2B

22. Enhanced Object Recognition and Spatial Memory Water Maze (hidden) Object Recognition

23. Enhanced fear conditioning (acquisition and extinction) Context and Tone fear conditioning Fear extinction

24. Tsien on Memory and Intelligence Does anyone remember what happened to HM’s IQ?

25. Joe Tsien on Doogie But does enhanced memory really translate as smarter? And what about intelligence? Do Doogies have a higher IQ? Joe: Actually we don't exactly know whether they have better memory or they have better analytical skills or they're just better everything. So it's a difficult thing to judge. And the same as when we do the IQ tests and where a person have higher IQ scores you cannot really tell them based on that one simple test they have a better memory or better analytical skills.

26. No measure of general intelligence in mice • Numerous studies equate good learning on simple memory tasks with high intelligence • Most of these tasks do not show big deficits with mental retardation mutations (even severe) • No appreciation for individual differences

27. No measure of general intelligence in mice • No way to pursue the genes for high g, because will select for specific ability (e.g., fear) • Same mice not even usually run on multiple tasks so no way to measure g • Several new studies quite promising • Doogie may indeed be smarter -> Tolman's rats were smarter on a variety of tasks, but they never really showed it was intelligence per se

28. What are Heritability, SharedEnvironment, andUnsharedEnvironment • High Heritabilitydoes not mean a trait is genetically determined • Heritability estimates are only valid for the enviornmental conditions under which they were taken • As a general rule, when environment varies little heritability goes way up; when environment is changing or variable heritability goes way down. • Gene-environent interaction is the rule; not genetic determinism (i.e., Huntington's disease, or familial breast cancer areexceptions)

29. Gene-environment interaction is the rule genetic environmental Lewontin (1976)

30. Typical enrichment experiment by Psychologists (Hebb, 1949)

31. Influence of Rearing Environment Cooper & Zubeck (1950)

32. Flynn, J. (1987). Massive IQ gains in 14 nations. What IQ tests really measure. Psychological Bulletin, 101, 171-191. Flynn Effect • Noticed norms needed constant updating • Average gain about 3 points per decade • 19-year-olds in Netherlands went up more than 8 points from 1972-1982

33. Flynn Effect in the US, 1932 vs 1997

34. Concept of Reaction Range

35. Summary • Large heritable component to intelligence and memory ability and setting reaction range • Many genes involved • Environment plays a key role in determining where in the reaction range an individual falls • Genetic enhancement of memory and intelligence is feasible.