1 History: defining & measuring intelligence zSir Francis Galton ( ) ygenes & family lines yintelligence = biological capacity yreaction times & sensory acuity xlater research contradicted these measures

2 History: defining & measuring intelligence zAlfred Binet ( ) yBinet-Simon Test France, 1905 yintelligence = collection of higher- order mental abilities loosely related to one another yintelligence is nurtured ymental age

3 History: defining & measuring intelligence zCharles Spearman ( ) yliked Binet’s methods of testing yliked Galton’s idea that intelligence was a single entity ydeveloped “factor analysis” ytwo factors x“g” = general intelligence x“s” = specific ability yscore 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

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

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

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

7 Modern intelligence tests zThe 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

8 Modern intelligence tests zThe Wechsler tests yused more widely now than Stanford- Binet ymodeled after Binet’s, also made adult test xWISC-III for children xWAIS-III for adults

9 Standardized scoring of Wechsler tests zAll raw scores converted to standardized scores zNormal distribution zMean of 100 zStandard deviation of % 13.59%34.13% 13.59%2.14% 0.13% 95.44% 68.26% Wechsler IQ score Number of score

10 How valid are IQ tests? zValidity = test measures what it’s intended to measure zDoes test correlate with other measures of same construct? zSchool achievement yIQ tests (I.e., S-B and the Wechsler) correlate highly ybut they were designed to test stuff that you learn in school zPrestigious positions zOn-the-job performance & other work-related variables

11 What do IQ tests measure about your mind? zMental 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 zWhy is this important? ymental quickness may expand capacity of working memory

12 What do IQ tests measure about your mind? zMental self-government zSternberg 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

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

14 Summary z Validity of IQ tests y are they really measuring intelligence? z What do IQ tests measure? y mental quickness y mental self-government