2 What is intelligence?Where does it come from?How can it be measured?
3 What is Intelligence? Some definitions Binet defined intelligence as an individual’s capacity to:Find and maintain a definite direction or purposeAdjust strategy as necessary to achieve that purposeEvaluate or criticize that strategy so adjustments could be madeWechslerThe aggregate or global capacity of an individual to act purposefully, think rationally, and deal effectively with the environmentKaplan and SaccuzzoGeneral potential independent of prior learning
4 Spearman’s Theory of General Mental Ability VerbalReasoningQuantitativeReasoningLogicalReasoning
5 Cattel & Horn’s Theory of Intelligence CrystallizedAbilitiesFluidAbilitiesVerbalReasoningQuantitativeReasoningAbstract VisualReasoningVocabulary testComprehension testAbsurdities testVerbal relations testQuantitative testNumber series testEquation building testPattern analysis testCopying testMatrices testPaper folding & cutting test
8 History of Intelligence Testing First intelligence tests were devised by Francis GaltonIn 1905, Binet developed test to measure child’s mental ageLewis Terman revised the Binet scale to produce the Stanford-Binet (introduced IQ)Weschler (1939) published improved measure for adults (introduced deviation IQ)
10 Intelligence Testing Today Intelligence tests contain diverse mix of questions assessing abstract reasoningUse modern deviation IQ scores normed for ageTypically M=100 SD=15IQ scores vary across testings but intelligence tests have high reliabilityIntelligence tests have demonstrated “limited” validityIQ tests are not widely used in non-Western cultures
11 Where Does Intelligence Come From? Nature (Hereditary)Twin studiesAdopted childrenHeritability ratiosNurture (Environment)Adoption studiesEnvironmental deprivationEnvironmental enrichmentGenerational increasesInteraction ModelIntelligence influence by both factorsHeredity and environment also interactReaction range model
12 Cultural Differences in IQ Scores Average IQ scores for large minorities is somewhat lower than the average for whitesJensen and others argue these differences result from heredityKamin’s rebuttalSocioeconomic disadvantageCultural test biasMercer (1975) IQ argued tests measure ability and assimilation into mainstream cultureNot much empirical evidence that this is a problem