Intelligence

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“Copyright © Allyn & Bacon 2007

What is intelligence?

Think of the smartest people you know. What makes you think they are intelligent?

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The World’s Smartest: Potential and Pitfalls

Child Genius

World’s Smartest Man

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Intelligence

What is intelligence? Are there different types of intelligence? If so, how many? Can intelligence be measured? Not all psychologists agree on the answers

to these important questions

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What Is IQ?

IQ: Intelligence QuotientScore on an intelligence testMeaning has changed over time; also, how

mutable it is and origins of between group differences.

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Intelligence Testing: History Alfred Binet and Theodore Simon

Developed first intelligence test (1904-1911)Identify students who need extra helpTest many normal children at each ageCompare individual’s score to “normal”

scoresMental ageChronological age

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Intelligence Testing: History Lewis Terman (Stanford University)

Developed American version of the Binet-Simon test, called the Stanford-Binet test, for ages 2 to adult

David WechslerWechsler Adult Intelligence Scale (WAIS)Wechsler Intelligence Scale for Children (WISC)Performance and verbal subtests

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Wechsler Adult Intelligence Scale

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Calculating IQ

William SternProblem: people don’t get stupider with age

Modern approachCompare individual to standardized sample

IQ =mental age

chronological agex 100

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The Normal Curve

Population Norming

Mean Standard deviation

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Reliability and Validity

A good test must be valid and reliable Reliability

Test produces consistent results

ValidityTest measures what it is supposed to

The WAIS-III is highly reliable, but is it a valid measure of intelligence?

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IQ and Achievement

IQ tends to be related to achievementHigh school and college gradesJob prestige and salaryMarital stability

However, IQ accounts for only a small amount of the variation in job success

Correlation is not causation Motivation, education, culture are important

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One Intelligence or Many? Charles Spearman

g: general factors: specific factorsIntelligence depends mostly on gFactor analysis

Louis ThurstoneSeparate primary mental abilitiesExamples: verbal comprehension and spatial

visualization

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One Intelligence or Many? Raymond Cattell and John Horn

Crystallized intelligenceFluid intelligence

AgingCrystallized intelligence doesn’t sufferFluid intelligence tends to decreaseDifferent aging effects support the distinction

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One Intelligence or Many? Carroll’s three-stratum model

Top strata is g, general intelligenceSecond strata includes fluid and crystallized

intelligence with 6 other broad abilitiesThird strata includes 69 specific abilities

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Emotional Intelligence (EI)

Knowing your emotions Managing your feelings Self-motivation Recognizing others’ emotions Handling relationships Women tend to have higher EI than men

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Multiple IntelligencesHoward Gardner (8 or 9 forms of intelligence) 1) Linguistic intelligence: The ability to use language

well. 2) Spatial intelligence: The ability to reason well about

spatial relations. 3) Musical intelligence: The ability to compose and

understand music. 4) Logical-mathematical intelligence: The ability to

manipulate abstract symbols. 5) Bodily-kinesthetic intelligence: The ability to plan

and understand sequences of movements. 6) Intrapersonal intelligence: The ability to understand

oneself. 7) Interpersonal intelligence: The ability to understand

other people and social interactions. 8) Naturalist intelligence: The ability to observe carefully. 9) Existential intelligence: The ability to address “the

big questions” about existence.

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Brain Size and Intelligence Is bigger always better?

Depends more on size of crucial brain areasFemales tend to have smaller brains but equal

IQsCorrelation between size and intelligence is

smallCorrelation is not causation

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IQ and Speed of Processing Is IQ correlated with speed of information

processing?Mixed resultsMany IQ subscales are time, so it is not

surprising that mental processing speed would be related to IQ

Measures of neural conduction are only weakly related to intelligence

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Working Memory and IQ

IQ is correlated with working memoryMany IQ subscales are involve memory, so

it is not surprising that mental processing speed would be related to IQ

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IQ: Genes and Environment Adoption studies

Correlation of IQs for identical twins raised apart is higher than that for fraternal twins and nontwin siblings raised together

An adopted child’s IQ correlates higher with the biological mother’s IQ than with the adoptive mother’s IQ

Strong evidence of the link between genes and IQ

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IQ: Genes and Environment Effects of environment

Stoolmiller (1999) estimated the effects of the environment on IQ to be 57%

MicroenvironmentReaction range

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Group Differences in IQ

Within-group versus between-group differencesGenetics accounts for 72% of IQ variation in

affluent environmentsGenetics accounts for 15% of IQ variation in

impoverished environments Race differences: Why? Test bias Environmental differences Microenvironments Sex differences

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Boosting IQ

The Flynn effectAverage IQ increases 3 points every 10

yearsExplanations?

○ Daily life is more challenging○ Nutrition is better○ Reasoning ability stressed by IQ tests has

gotten better, not IQ itself

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The Pygmalion Effect

Rosenthal & Jacobson“Harvard Test of Inflected Acquisition”Random selection of childrenSelf-fulfilling prophecy

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Educational Programs and IQ Head Start and similar projects

Most show only short-term IQ gainsMost gains evaporate over time

Abecedarian ProjectIntellectual, medical, and nutritional

enrichment5 years before kindergartenLong-term 5-point IQ boost

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Mental Retardation

IQ less than 70

4-7 million Americans

Islands of excellenceKim Peek

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Mental Retardation

Genetic influencesDown syndromeFragile X syndromeAutism

Environmental influencesFetal alcohol syndromeChildhood diseasesExposure to environmental toxinsInadequate medical care

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The Gifted

IQ of 150-180 Prodigies