Intelligence

1. Intelligence MEASURING HOW WELL WE THINK

2. History of Intelligence Testing • 1904: Alfred Binet created a test to identify mentally sub-normal children in education by measuring a child’s “mental age” • This early tests was intended to identify children in need of special training • Mental age: mental ability typical of a child of that chronological (actual) age • Example: If you are told that “Billy” displays the mental ability of a typical 7 year-old child, you would know his mentalage is 7.

3. History continued… • 1916: William Stern suggested an “intelligence quotient (IQ)” • IQ = mental age/chronological age x 100 • Example: If a child who is 10 years old has a mental age of 12, the child’s IQ would be 120 • Became the most commonly used IQ test worldwide • 1939: David Weschler published the 1st IQ test for adults • Two major innovations: test less verbally dependent & introduced a new scoring technique based on normal distribution

4. What do modern IQ scores mean? • Normal distribution: a symmetrical bell shaped curve (p. 241) that represents the pattern in which many characteristics are dispersed in the population • Most cases fall near the center of the distribution, and the number of cases gradually decline as one moves either direction from the center • Most human traits, ranging from height to running speed to spatial ability to intelligence, follow a normal distribution • 100=average (range 85 to 115) • 15 point spread between ranges • Levels: retarded—borderline—average—superior—gifted

5. Intelligence Tests Validity Reliability • Ability to measure what it was designed to measure • Validity of IQ tests usually concentrate on their relationship to grades • Measurement consistency • Yields similar results on repetition • IQ scores should be viewed as estimates that are accurate +/-5 pts 2/3rd of the time

6. Early pioneers believed that intelligence was inherited. • However, it has become clear that both heredity and environment influence intelligence. • Heritability of IQ is between 50 to 70 % • Heredity sets certain limits on our IQ and the environment determines where we fall within the limits. (Reaction Range) • For most people the range is 20-25 pts Heredity versus Environment

7. Evidence for Hereditary Influence • Twin Studies: • Research on identical and fraternal twins • Share the same environment—but also genetic factors • Identical twins: IQ has a very high correlation (.86), whereas fraternal twins (.60) • Identical twins reared apart display (.72) greater correlation than fraternal twins raised together • Adoption Studies: • Comparison of score for adopted children to biological parents • Measurable similarity

8. Evidence for Environmental Influence • Adoption Studies • Adopted children show some resemblance to their foster parents in IQ • Siblings reared together are more similar in IQ than those reared apart • Unrelated children who are raised in the same home show significant resemblance • Environmental Deprivation & Enrichment • Environmental deprivation due to isolation, poverty, neglect led to a predicted decline in IQ scores. • On the other hand, children in circumstances conducive to learning received benefits due to their environmental enrichment.

9. Generational Changes: • Performance on IQ tests has steadily increased over generations all over the world • WHY? • Proposed explanations: • Better nutrition • Technological Advances • Visual-spatial • Cognitive skills • Better schools • Smaller families • Better educated parents • Higher quality parenting • The Flynn Effect • Name given to the increase in IQ test scores since the 1930s industrialization. • Changes have been attributed to environmental factors, after all the gene pool could not change that rapidly!

10. Cultural Differences • IQ scores of minorities (blacks, Native Americans, & Hispanics) in the U.S. are somewhat lower than that of whites • Disparity = 3 to 15 pts • Why are the differences found? • Jensen argued it is due to heredity (extremely controversial) • The Bell Curve (Herrenstein & Murray) contended that IQ is the primary determinant of an individual’s success in life (implied what Jensen had said) p. 248 • Socioeconomic disadvantage-children from lower social classes tend to have IQ’s 15 pts lower below average • Minorities are over-represented in the lower social classes--ethnic differences are most like social class differences.

11. Expanding our look @ intelligence • Sternberg’s Triarchic theory of human intelligence (mid 1980s) • p. 251 • He asserts that there are three factors that influence successful intelligence: • analytical intelligence (abstract reasoning, evaluation, and judgment--typical of most IQ tests) • creative intelligence (generating new ideas) • practical intelligence (dealing with everyday problems)

12. New approaches • Howard Gardner’s Multiple Intelligences (1999) • Believes traditional tests are too narrow in focus (primarily verbal and mathematical) • Concluded that humans exhibit eight independent intelligences (p. 252) • Difficult to test/prove his theory! • Critics argue his use of the term “intelligence” is so broad that it almost becomes meaningless.

13. Essay questions: • Describe how the representative heuristic influences your decision making strategies. • OR • Identify and describe four potential problems to IQ testing.