Chapter 10: Intelligence
Chapter Outline
1.
2.
3.
4.
5.
6.
What do we mean by intelligence?
Additional types of intelligence
How do we measure intelligence?
Is intelligence governed by genetic or
environmental factors?
Intelligence: What happens in the brain?
Extremes in intelligence
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What Do We Mean by Intelligence?
 Intelligence
 Ability
to learn
 Ability to apply learned material to life and meet
the demands of the environment
 Metacognition—ability to understand and
control one’s cognitive activity
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Is Intelligence General or Specific?

Spearman’s two-factor
theory

Factor analysis—
statistical method to
determine whether two
or more items correlate,
thus forming a cluster
 s factor—specific
factor tied to a specific
area of functioning
 g factor—general
factor relating to all
clusters
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Is Intelligence General or Specific?

Lewis Thurstone
 Primary mental abilities—do not rely on general
intelligence
1. Verbal comprehension
2. Word fluency
3. Numerical skill
4. Spatial ability
5. Associative memory
6. Perceptual speed
7. Reasoning
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Modern Multifactor Theories of Intelligence
 Howard Gardner’s
Theory of multiple intelligences—there is no single,
unified intelligence, but instead independent
intelligences arising from different portions of the brain
 Linguistic
 Logical-mathematical
 Musical
 Spatial
 Bodily-kinesthetic
 Interpersonal
 Intrapersonal
 Naturalistic
 Modular model of mental functioning

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Modern Multifactor Theories
 Robert Sternberg

Triarchic theory of
intelligence—intelligence
is made up of three
interacting components
 Internal—analytical
 Most related to
traditional IQ tests
 External—creative
 Experiential—practical
 Helps us to adapt to our
environment
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Modern Multifactor Theories
 Stephen Ceci

Bioecological model
of intelligence—
intelligence is a function
of the interaction
between:
 Innate potential
abilities
 Environment
 Motivation
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Additional Forms of Intelligence
 Emotional Intelligence
 Ability
to perceive, express, assimilate, and
regulate emotion
Possess empathy and emotional control
 Social Intelligence
 Ability to function in social settings
Possess ability to get along well in relationships,
school, work
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Additional Forms of Intelligence
 Wisdom
 Ability
to make sound judgments
Function of practical intelligence
 Creativity
 Ability to generate valuable, original ideas
intrinsic motivation, imagination, game
personality
 Personality Characteristics
 Intelligence is the cognitive part of personality
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How Do We Measure Intelligence?
 Psychometric approach —measure intelligence
through psychological testing
Mental age—intellectual age at which a person is
functioning
 Intelligence quotient (IQ)—ratio of mental age to
chronological age multiplied by 100

 Intelligence test construction and interpretation

Standardization—the use of uniform procedures to
administer and score the test
 Individual scores are compared with the sample scores
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How Do We Measure Intelligence?
Test construction continued

Reliability—Consistency in measurement
 Test-retest
reliability—administer the test more than once
 Split-half reliability—divide the items on a single test among
two groups

Validity—accuracy of the measurement
 Content
validity—how well a test accurately measures what it
is intended to measure
 Validity coefficient—correlation between measurement
scores and external criteria.
 Predictive validity—correlation between scores and future
behaviour
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Standardization
 Normal distribution

A symmetrical, bell-shaped distribution in which most scores are in
the middle with smaller groups of equal size at either end.
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Measures of Central Tendency
 A single value that describes the typical or the central
score in the set of scores
 Three types of central tendency
 Mode—the value that occurs most frequently
 Median—the middle value; the 50th percentile,
where 50% of scores are above and 50% of scores
are below
 Mean—the average; the sum of all the scores
divided by the number of cases; the most
commonly used measure of central tendency
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History of Intelligence Testing
 Galton—theory of psychophysical performance
Psychic energy and heightened sensitivity to external stimuli
 Developed tests of an individual’s sensory processing, motor
skills, and reaction time
 Binet-Simon intelligence test
 Developed the first standardized intelligence test
 Introduced the idea of mental age
 Lewis Terman
 Adapted the Binet-Simon intelligence test for use in the
United States
 Developed the intelligence quotient (IQ): MA/CA × 100

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Eugenics
 Terman believed that his IQ test could help
determine the “fitness” of individuals to reproduce
 Alberta in 1928 and BC in 1933 enacted laws
requiring individuals deemed mentally retarded or
mentally ill to be sterilized
 These laws were repealed in 1972
 Terman administered his test to newly arrived
immigrants to the United States
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Wechsler and the WAIS
 David Wechsler recognized two problems with the
tests:
The distinction between mental and chronological age
becomes less informative when testing adults
 The need for greater fairness when testing people who do
not speak English

 Developed the Wechsler Adult Intelligence Scale
(WAIS) and the Wechsler Intelligence Scale for
Children (WISC)
 Compare individual scores to scores obtained over a
very large sample of individuals using the normal
distribution
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Wechsler and the WAIS
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How Well Do Intelligence Tests Predict
Performance?
 Stanford-Binet and WAIS
 Popular intelligence tests
 High degrees of reliability
 Predictive of school performance
 High correlation between scores and number of
years of schooling
 Some correlation with occupational and social
achievements, income, and health-related
behaviours, including better health throughout life,
greater independence during old age, and a longer
lifespan
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Cultural Bias and Stereotypes
in Intelligence Testing
 Racial groups differ in their average scores on
traditional intelligence tests
 What explains this finding?
 Tests are culturally biased
Sample of a culturally unfair question:
 Caesar is to salad as __________ is to brandy.
a. Churchill b. Napoleon c. Hitler d. Lincoln
 Stereotype vulnerability or threat—when people
perform poorly as a result of a fear that their
performance will conform to a negative stereotype
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Progressive Matrices Test
 Emphasizes abstract,
nonverbal skills
 Less culture bias
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Is Human Intelligence Increasing?
 Flynn effect—rise in average IQ scores over time
throughout the world
 Intelligence test scores have increased over time,
however other standardized test scores have
dropped
 Consider the relationship between the two types of
measures:
Why aren’t scores both rising or both falling?
What does this tell us about the measures?
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The Flynn Effect
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Is Intelligence Governed by Genetic or
Environmental Factors?
 Genetic factors
 Heritability
coefficient—indicates the
contribution of heredity to a characteristic (+0.50
for intelligence)
 Twin studies
Higher correlation between identical twins’
intelligence scores (+.86) than fraternal twins
(+.60)
Identical twins reared apart show a correlation of
+.75
 Reaction range—the upper and lower level of
intelligence made possible by a child’s genetic
nature
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Is Intelligence Governed by Genetic or
Environmental Factors?
 Environmental factors
 Family
and home environment
Sibling studies (+.32 adopted, non-biological
siblings, raised together, and +.22 biological
siblings raised apart)
 School influences
Both a cause and a result of intelligence
 Intelligence is related to success in school
 Schooling improves mental abilities
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Is Intelligence Governed by Genetic or
Environmental Factors?
 Environmental factors continued
Cultural influences—definition of intelligence varies from
culture to culture
 The expression of intelligence is tied to the survival needs
of a culture


Occupational influences—people of higher intelligence
tend to work in more complex jobs, but complex work
may itself improve intelligence
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Group Differences in IQ Scores
 Racial groups differ in their average scores on intelligence
tests
 High-scoring people (and groups) are more likely to attain
high levels of education and income
 Aboriginal Canadians score, on average, 15 to 20 points lower
on intelligence tests than their non-Aboriginal contemporaries
 Aboriginal students are twice as likely to drop out of high
school
 Aboriginal children and youth need to work in school
systems that acknowledge and celebrate Aboriginal values
and heritage
 Public policy aimed at making more equitable resources
available throughout society would lead to more similar
intelligence test scores across different groups
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Variation Within and Between Groups
 Environment contributes to variation between the
groups
 An average variation between groups cannot be
applied to individuals within each group
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Does Environmental Enrichment Make a
Difference?
 Head Start
 Head Start is a government-funded preschool
program that serves children who come from
families below the poverty line
 Aims to enhance children’s chances for success in
school and beyond by boosting their cognitive and
social skills
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Does Environmental Enrichment Make a
Difference?
 Does it work?
 It produces short-term increases in cognitive skills, but
only for impoverished children
 It increases children’s readiness for school, enhances
emotional intelligence, reduces school dropouts, and
decreases later criminality
 Better programs:
 Begin early in life and continue
 Are intensive (more hours per day and more days per
year)
 Include programs for maintaining positive attitudes
and behaviours
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What Happens in the Brain?
 Brain size
General intelligence is
associated with the number or
neurons in the frontal lobes
 Brain speed—how fast the brain
responds to stimuli
 EEG tests
 Those who perceive the
correct image more quickly
tend to score higher on
intelligence tests
 Nerve conduction velocity
(NCV)—speed of impulses along
nerve fibres and across synapses

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What Happens in the Brain?
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What Happens in the Brain?
 Brain glucose activity

PET scans show
metabolism of glucose with
active areas in different
colours than inactive areas
 The left lateral prefrontal
cortex is activated when
performing verbal tasks
 Both lateral prefrontal
cortexes are activated
when performing spatial
tasks
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Cortical Thickening and Intelligence
 The development of intelligence involves a process of
synaptic and neural growth and then pruning,
particularly in the prefrontal cortex
 The cortex thickens and thins out again throughout
childhood and adolescence
 The processes of growth and pruning unfold over a
much longer developmental span in highly intelligent
people than they do in less intelligent individuals,
perhaps because more complex and sophisticated
neural circuits are being constructed
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Extremes in Intelligence
 Mental retardation—general intellectual
functioning that is well below average with poor
adaptive behaviour
 Mild retardation
Usually not recognized until school age
Benefit from schooling
Linked to environment
 Moderate, severe, and profound retardation
Diagnosed early in life
Largely biological
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Extremes in Intelligence
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Extremes in Intelligence
 Down syndrome—the most common of the
chromosomal disorders leading to mental
retardation
 Fewer than 1 of every 1,000 live births
 Rate increases greatly when the mother’s age is
over 35
 Extra chromosomal material on the 21st
chromosome
 Small head, flat face, slanted eyes, high cheekbones
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Extremes in Intelligence
 Giftedness—natural ability, talent, or intelligence
 The
top 1 or 2 percent of a tested population
 Evident at a young age
 Environmental contributors
 Intrinsically motivated
 May occur in some areas and not others
Example: academically gifted but not socially
gifted
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