20 40 70605030 80 100 13012011090 140 160 180170150IQ

Percentage of group

24

20

28

4

12

8

16

Fig10_4

8_6

Copyright © Houghton Mifflin Company. All rights reserved.

Source: Reprinted with permission from “Familial Studies of Intelligence: A Review,” T. Bouchard et al., Science, Vol 212, #4498, pp. 1055-9,29 May 1981. Copyright © 1981 American for the Advancement of Science.

+0.10

+0.20

+0.30

+0.40

+0.50

+0.60

+0.70

+0.80

+0.90

+1.00

Correlation of IQ scores

Identical twins reared together

Identical twins reared apart

Non-identical twins reared together

Siblings reared together

Siblings reared apart

Unrelated children reared together

Unrelated children reared apart

Fig8

04

KEY COMPARISONSTYPE OF STUDY OBJECTIVE

Same geneticrelatedness,differentenvironments

Twin

Adoption

Differencesin geneticrelatedness,same environment

Identical twinstogether

Identical twinsapart

Identical twinstogether

Fraternal twinstogether

Fig10_6

10_06

European-Americans

Asian-Americans

African-Americans and Hispanic-Americans

Averages

31

INFORMATION-PROCESSINGINTELLIGENCE

Mental steps or "components"used to solve problems

CREATIVE INTELLIGENCE

Use of experience in ways thatfoster insight

PRACTICAL INTELLIGENCE

Ability to read and adapt tothe contexts of everyday life

InRev10a

InRev9aInRev7aInRev6bInRev6aInRev5bInRev5aInRev4bInRev2aINFLUENCES ON IQ SCORES

Genes appear to play a significant role in differences among people on IQ test performance.

Environmental conditions interact with genetic inheritance. Nutrition, medical care, sensory and intellectual stimulation, interpersonal relations, and influences on motivation are all significant features of the environment.

Source of Effect

Genetics

Environment

DescriptionExamples of Evidencefor Effect

The IQ scores of siblings who share no common environment are positively correlated. There is a greater correlation between scores of identical twins than between those of nonidentical twins.

IQ scores have risen among children who are adopted into homes that offer a stimulating, enriching environment. Correlations between IQs of twins reared together are higher than for those reared apart.

InRev10b

ANALYZING MENTAL ABILITIES

Define the structure of intelligence by examining factor analyses of the correlations between scores on tests of mental abilities.

Understand intelligence by examining the mental operations involved in intelligent behavior.

Understand intelligence by examining the information processing involved in thinking, changes with experience, and effects in different environments.

Understand intelligence by examining test scores, information processing, biological and developmental research, the skills valued by different cultures, and exceptional people.

Approach

Psychometric

Information processing

Sternberg’s triarchic theory

Gardner’s theory of multiple intelligences

MethodKey Findingsor Propositions

Performance on many tests of mental abilities is highly correlated, but this correlation, represented by g, reflects a bundle of abilities, not just one trait.

The speed of basic processes and the amount of attentional resources available make significant contributions to performance on IQ tests.

There are three distinct kinds of intelligence: analytic, creative, and practical. IQ tests measure only analytic intelligence, but creative intelligence (which involves dealing with new problems) and practical intelligence (which involves adapting to one’s environment) may also be important to success in school and at work.

Biology provides the capacity for eight distinct “intelligences”: linguistic, logical-mathematical, spatial, musical, body-kinesthetic, intrapersonal, interpersonal, and naturalistic.

Fig99

32

Average Score

Inductive reasoningSpatial ability

Verbal abilityNumeric ability

60

55

50

45

40

35

3029 39 46 53 60 67 74 81 88

MOTIVATION AND EMOTION

How does excessive emotional arousal affect scores on tests of mental ability? (p. 340)

MEMORY

Is mental retardation mainly a matter of poor memory?  (p. 352)

RESEARCH IN PSYCHOLOGY

Which research designs are best for studying changes in mental abilities as people age ? (p. 346)

LINKAGESto Mental Abilities