Chapter 9: Intelligence &
Language
Amber Gilewski
Tompkins Cortland Community College
The Evolution of Intelligence Testing
• Sir Francis Galton (1869)
– Hereditary Genius
• Alfred Binet and Theodore Simon (1905)
– Binet-Simon Intelligence Scale
– Mental age
• Lewis Terman (1916)
– Stanford-Binet Intelligence Scale
– Intelligence Quotient (IQ) = MA/CA x 100
created by William Stern
• David Wechsler (1939)
– Wechsler Adult Intelligence Scale
Factor Theories of Intelligence
• Intelligence is made up of a number of mental
abilities (factors)
• Spearman’s g factor
– General intelligence
– s factor represents specific intelligence
• Thurstone’s eight specific factors
– Primary mental abilities
Theories of Intelligence
– Sternberg’s triarchic theory
(analytical, creative, practical)
– Gardner’s multiple
intelligences
(musical, bodily kinesthetic,
logical-mathematical, linguistic,
spatial, interpersonal,
intrapersonal, naturalist,
existential)
– Goleman’s emotional
intelligence: understanding
emotions in self and others;
regulating emotions
Approximate Distribution of IQ Scores
Differences in Intellectual Functioning
• Socioeconomic and Ethnic Differences
– Consideration of social class
• Lower-class U.S. children score 10 – 15 IQ
points lower than middle- and upper-class
– Consideration of ethnicity
• Impact of social class
– Asian Americans more likely to graduate high
school and complete college
Do Intelligence Tests Contain Cultural Biases?
• Tests may measure familiarity with dominant
middle-class culture
• Culture-free Intelligence Tests
– Cattel’s Culture-Fair Intelligence Test
– Goodenough’s Draw-A-Person test
• European American children outperform African
American children on “culture-free” test
• Steele’s stereotype vulnerability
• Ethnic differences vs. social class
Figure 9.17 Genetics and between-group differences on a trait
Gender Differences in Intelligence Tests
• Intelligence tests do not show overall differences
in cognitive ability
– Girls superior to boys in verbal ability
– Boys excel in visual-spatial ability
– Boys tend to score higher on math tests
• Group scores represent greater variation within
the group than between the groups
Genetic Influences on Intelligence
• Kinship studies
– IQ scores of identical twins are more alike
than for any other pairs
• Twin Studies
– IQ scores of MZ twins reared together have
higher correlation than MZ twins reared apart
• Adoption Studies
– Stronger relationship between IQ scores of
adopted children and their biological parents
than between children and adoptive parents
Heritability of Intelligence
• Heritability is between 40% and 60%
– About half the difference between your IQ
score and the IQ scores of other people can
be explained by heredity
• Environment is also important
• Being reared together is related to IQ
similarities
• Cumulative deprivation hypothesis
• Concept of “reaction range”
Findings of Studies of the Relationship
between IQ Scores and Heredity
Environmental
Influences on
Intelligence
• Home Environment
– Important predictor of
IQ scores - ages 3 to 8
• Education
– Enriched early
environments (Head
Start)
The Flynn Effect
• Western world – IQ
scores rose
substantially between
1947 and 2002
– Impact of social and
cultural factors
• Changes also
demonstrated in
subpopulations
– Educational gap
between races in U.S.
is narrowing
The Complex Web of Factors That Affect
Intellectual Functioning