Unit 6: Testing & Individual Differences

Module 33: Genetic & Environmental Influences on Intelligence

Unit 6: Testing & Individual DifferencesGenetic InfluencesDo people with the same genes share comparable mental abilities?Answer: YES!IQs of identical twins are similar to those of the same person taking the same test twice.Fraternal twins (share of their genes) are much less similar.Identical twins raised separately also have similar scores.Genetic InfluencesFraternal twins tend to score more alike than other non-twin siblings.Intelligence scores of adopted children are more like those of their biological parents. Sogenetics seem to play a large role in IQ.Genetic Influences

Genetic Influences

Genetic Influences

Genetic Influences

Genetic Influences

Environmental InfluencesEnvironmental 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!Environmental InfluencesCan 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 timeSmall intelligence boost, but experiences after Head Start is important.

Environmental InfluencesOf courseschooling 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.Racial & Ethnic DifferencesRacial groups differ in average scores on IQ tests. Bell curve:Whites: Average 100Blacks: Average 85Hispanics: Average in between whites and blacks.Similar results appear on aptitude tests like SAT, although gap is getting smaller.Racial & Ethnic DifferencesEnvironmental 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.)

Racial & Ethnic DifferencesIQ scores of todays 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.

Gender DifferencesBoys 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.

Gender DifferencesBoys 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.

BiasBias: 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.

BiasStereotype Threat: A self-confirming concern that one will be evaluated based on a negative stereotype.When one feels that they wont succeed based on negative stereotypes, they usually perform poorly.This may account for lower test scores of blacks and women.