Unit 6: Testing & Individual Differences

1. Unit 6: Testing & Individual Differences Module 33: Genetic & Environmental Influences on Intelligence

2. Genetic Influences • Do people with the same genes share comparable mental abilities? Answer: YES! • IQ’s of identical twins are similar to those of the same person taking the same test twice. • Fraternal twins (share ½ of their genes) are much less similar. • Identical twins raised separately also have similar scores.

3. Genetic Influences • Fraternal twins tend to score more alike than other non-twin siblings. • Intelligence scores of adopted children are more like those of their biological parents. • So…genetics seem to play a large role in IQ.

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9. Environmental Influences • Environmental influences effect children of less-educated parents more. • Children in poor families have more similar intelligence scores. • Meaning that poor environmental conditions can override genetic differences. • Extreme poverty trumps genetics!

10. Environmental Influences • Can intelligence be improved with practice or education? • Head Start Program: Government funded preschool program. • Targeted children below poverty level. Over 900,000 children. • Quality programs increase school readiness, but results fade over time • Small intelligence boost, but experiences after Head Start is important.

11. Environmental Influences • Of course…schooling and intelligence is correlated. • IQ scores rise during school year, but drop during summer. • Flynn Effect: worldwide rise in IQ scores since the 1920s due to increasing years of schooling. • More school = more intelligence.

12. Racial & Ethnic Differences • Racial groups differ in average scores on IQ tests. • Bell curve: • Whites: Average – 100 • Blacks: Average – 85 • Hispanics: Average in between whites and blacks. • Similar results appear on aptitude tests like SAT, although gap is getting smaller.

13. Racial & Ethnic Differences • Environmental factors in racial gap: • Skin color does not differentiate people. • Race is no longer easy to define with more mixed race people. • Asians outperform North Americans on math and aptitude tests. (They also spend 30% more time in school.)

14. Racial & Ethnic Differences • IQ scores of today’s better-fed, better-educated population exceeds those of the 1930s. (Flynn Effect) • White and black infants score equally well on infant intelligence measures. • Each ethnic group had their glory years: Greeks, Egyptians, Romans, Aztecs, Arabs, etc.

15. Gender Differences • Boys vs. Girls: • Spelling: Girls are better spellers. • Verbal: Girls are more verbally fluent and remember words better. • Memory: Girls are better at locating objects. • Sensation: Girls are more sensitive to touch, taste, and odor.

16. Gender Differences • Boys vs. Girls Continued: • Emotion Detection: Girls! • Underachievement: More boys are at the low extremes of intelligence. • Math and Spatial Intelligence: Girls are better at computation, but boys are better at problem solving. Also more boys at the highest extremes in math.

17. Bias • Bias: Differences in performances caused by cultural experiences detected on tests. • Most psychologists believe that the major aptitude tests (ACT, SAT, IQ tests) are not biased. • Their predictions applies to both genders and all ethnic and economic groups.

18. Bias • Stereotype Threat: A self-confirming concern that one will be evaluated based on a negative stereotype. • When one feels that they won’t succeed based on negative stereotypes, they usually perform poorly. • This may account for lower test scores of blacks and women.