History defining measuring intelligence z Sir Francis Galton

History: defining & measuring intelligence z. Sir Francis Galton (1822 -1911) ygenes & family lines yintelligence = biological capacity yreaction times & sensory acuity xlater research contradicted these measures 1

History: defining & measuring intelligence z. Alfred Binet (1857 -1911) y. Binet-Simon Test France, 1905 yintelligence = collection of higherorder mental abilities loosely related to one another yintelligence is nurtured ymental age 2

History: defining & measuring intelligence z Charles Spearman (1863 -1945) y liked Binet’s methods of testing y liked Galton’s idea that intelligence was a single entity y developed “factor analysis” y two factors x“g” = general intelligence x“s” = specific ability y score on any given test depends on a combination of these 2 factors xg accounts for the similarity in test results xs accounts for the differences in test results 3

History: defining & measuring intelligence z. Raymond Cattell (1905 - ) ystudent of Spearman’s ymodified Spearman’s intelligence theory ythought that general intelligence was not one factor but two 4

Cattell’s Fluid & Crystallized Intelligence z. Fluid intelligence yability to perceive relationships without previous specific experience ymatrices tests or verbal analogies 5

Cattell’s Fluid & Crystallized Intelligence z. Crystallized intelligence ymental ability derived from previous experience xword meanings xuse of tools xcultural practices 6

Modern intelligence tests z. The Stanford-Binet Scale ymodification of the original Binet. Simon, after original came to US yintelligence quotient (IQ) = child’s mental age divided by child’s chronological age yused widely in the US, not as much as previously 7

Modern intelligence tests z. The Wechsler tests yused more widely now than Stanford. Binet ymodeled after Binet’s, also made adult test x. WISC-III for children x. WAIS-III for adults 8

z All raw scores converted to standardized scores z Normal distribution z Mean of 100 z Standard deviation of 15 Number of score Standardized scoring of Wechsler tests 68. 26% 95. 44% 0. 13% 2. 14%13. 59%34. 13%13. 59%2. 14% 50 70 85 100 115 130 Wechsler IQ score 9 145

How valid are IQ tests? z Validity = test measures what it’s intended to measure z Does test correlate with other measures of same construct? z School achievement y IQ tests (I. e. , S-B and the Wechsler) correlate highly y but they were designed to test stuff that you learn in school z Prestigious positions z On-the-job performance & other work-related variables 10

What do IQ tests measure about your mind? z Mental speed and span of working memory ytypically use a digit span test to measure this ymore recent studies find significant correlations between reaction times and IQ scores z Why is this important? ymental quickness may expand capacity of working memory 11

What do IQ tests measure about your mind? z Mental self-government z Sternberg ystudies more complex decision-making abilities ystates that the mind is made up of different components, each of which works on different problem solving tasks 12

Summary z History of intelligence testing yhow did each figure define & measure intelligence? z Modern intelligence testing y. Stanford-Binet vs. Wechsler tests ystandardized scoring -- what is “average? ” 13

Summary z. Validity of IQ tests yare they really measuring intelligence? z. What do IQ tests measure? ymental quickness ymental self-government 14