1. Intelligence Josée L. Jarry, Ph.D., C.Psych. Introduction to Psychology Department of Psychology University of Toronto July 14, 2003

2. Intelligence Testing has existed for nearly 100 years what do the tests really measure? are they valid predictors of scholastic ability? do individual differences in scores arise from genetic differences? or from differences in opportunity and experience?

3. Defining Intelligence Psychologists and educators define intelligence as the capacity for: –abstract reasoning, problem solving, and the capacity to acquire new knowledge –memory, adaptation to one's environment, mental speed, linguistic competence, mathematical competence, general knowledge, and creativity –sensory acuity, goal directedness, and achievement motivation.

4. Mental Quickness & Acuity Sir Francis Galton (1822-1911 ) Hereditary Genius (1869) –the capacity for high intellectual achievement is inherited –intelligence is the speed and accuracy with which one can detect and respond to environmental stimuli –invented the correlation coefficient.

5. Intelligence: a Collection of Abilities Alfred Binet (1857-1911) –Binet-Simon Intelligence Scale (1905) –intelligence is a collection of various higher order mental abilities only loosely related to one another –intelligence is nurtured through interaction with the environment –the goal of schooling is to increase intelligence –introduced “Mental age” in 1908.

6. Intelligence & Factor Analysis Charles Spearman (1863-1945) –developed a new battery of mental tests and factor analysis –found two separate factors –G for general intelligence –S for specific ability –a person's score on any given test depends on the combination of G & S –assumed that general intelligence represents biologically endowed ability.

9. Fluid & Crystallized Intelligence Raymond Cattell (1905-) Fluid intelligence –the ability to perceive relationships independently of previous practice or instructions –peaks at age 22 to 25 and then declines gradually Crystallized intelligence –a mental ability derived directly from previous experience –continues to increase until about age 50.

11. Testing Fluid & Crystallized Intelligence Fluid Intelligence –Soon is to Never as Near is to: a) not far, b) seldom, c) nowhere, d) widely? Crystallized Intelligence –Runner is to Marathon as Oarsman is to a) boat, b) regatta, c) fleet,d) tournament?

13. Introduction of IQ Lewis Terman –adapted the Binet-Simon test to North- American standards in 1916 –"Stanford-Binet" after Stanford University –adapted the scoring modification developed by Stern (1912) who introduced the notion of IQ –IQ = MA/CA X 100 –as chronological age increases, IQ has to decrease.

14. Adult Intelligence Testing David Wechsler –developed an intelligence tests for adults inspired by the Binet-Simon –made the notion of mental age obsolete by using the average score for a norm group and establishing norms for different ages –the average IQ is 100 –performance above or below average results in an IQ above or below 100 –results in a normal distribution of IQs.

16. The Validity of IQ Tests If intelligence tests measure intellectual ability, then IQ scores should correlate with other indices of intellectual ability The correlation between IQ and school grades ranges from.30 to.70 The correlation between IQ and performance in job requiring high intellectual ability ranges between.20 and.40

17. IQ: Nature or Nurture Nature –refers to the person’s biological inheritance Nurture –refers to the entire set of environmental conditions to which the person is exposed Are psychological differences among people primarily the result of differences in their genes (nature) or in their environment (nurture)?

18. IQ Heritability Twins studies –Identical twins are genetically identical –Fraternal twins are like non-twin siblings and are only 50 % related to one another –The correlation between IQs of identical twins is considerably greater than for fraternal twins –This indicates that genes play an important role in IQ –The correlation between fraternal twins’ IQs in adulthood drops, but that of identical twins does not.

20. Identical Twins Raised Apart –identical twins share 100% of their genes, but their environments is no more similar to each other than are the environments of any two members of the study population taken randomly –the average correlation coefficients between the IQ of identical twins raised apart is.73 –fluid and crystallized intelligence are equally heritable –fluid intelligence influences the acquisition and recall of facts.

21. Influence of The Family on IQ pairs of adoptive sibling who are genetically unrelated but are raised together are studied correlation greater than “0” between IQs must be due to shared environments when unrelated siblings are still children, their IQs correlate positively:.25 the correlation is completely lost in adulthood the correlation between IQs of genetically unrelated adults who have been raised in the same family is -.01

22. IQ, Race & Culture Blacks in the US score on average 15 points lower than whites on standard IQ tests Heritability studies explore IQ differences within groups, not between groups Differences within one group tell us nothing of the differences between groups.

24. Racial Differences Explained if whites are genetically superior to blacks in IQ, mixed race individuals should have intermediate IQs one study identified a sample of black children in Chicago who had IQs in the superior range (125 or better) the proportion of European ancestry in the high IQ black children was neither more nor less than that in the black population at-large modern biochemical methods show no relationship between ancestry and IQ.

25. Social Designation and IQ (1) Autonomous minorities –are groups who have deliberately separated themselves from the mainstream and are proud of their heritage Immigrants minorities –are groups who integrate in hopes of bettering themselves –are relatively detached of the majority’s appraisal of them.

26. Social Designation and IQ (2) Involuntary minorities or castelike minorities –are groups who did not choose their minority status –are routinely judged as inferior by the dominant majority –castelike minorities everywhere perform more poorly in school and score on average 10 to 15 points lower on IQ tests than the dominant majority.

27. Varieties of Intelligence Left vs. right hemisphere intelligence –left hemisphere lesions in the language area can completely abolish a person's ability to speak or to think in words without affecting the ability to read maps or to solve spatial puzzles –A right hemisphere lesion in a specific location can have just the opposite effect –lesions in the left hemisphere tend to depress people's scores on tests that measure verbal knowledge and verbal reasoning while leaving performance on other tests intact.

29. Extreme Intellectual Specialists Retarded savants –severely impaired in most intellectual realms –but develop superior ability in one intellectual realm such as music, arts, or mental arithmetic –savants use rules, not just memory Confirms that ultimately, intelligence is a collection of relatively unrelated abilities These abilities appear related in normal individuals.