Download Chapter Summary Chapter 10: Intelligence What Do We Mean by

Chapter Summary
Chapter 10: Intelligence
What Do We Mean by Intelligence?
LEARNING OBJECTIVE 1 Describe various ways in which intelligence has been defined and
summarize the current thinking on whether intelligence is general or specific.
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Scholars early in the twentieth century defined intelligence as the ability to learn and to meet
the demands of the environment effectively. Later, other scholars added to this definition the
ability to understand and control one’s mental activities, called metacognition.
A central issue in defining intelligence is whether it is a single, general factor or a cluster of
different abilities. Charles Spearman hypothesized that a general factor, or g factor, underlies
all mental abilities, while Lewis Thurstone argued that intelligence is made up of seven
distinct primary mental abilities.
Although most theorists today agree that intelligence does include a g factor, modern
theorists such as Howard Gardner, Robert Sternberg, and Stephen Ceci have tended to
deemphasize the g factor and focus on specific abilities, or s factors.
Additional Types of Intelligence
LEARNING OBJECTIVE 2 Discuss several proposed types of intelligence that go beyond
intellectual functioning.
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Other theorists have broadened the definition of intelligence further to include emotional
intelligence, social intelligence, wisdom, creativity, and personality.
How Do We Measure Intelligence?
LEARNING OBJECTIVE 3 Identify important considerations in the construction of intelligence
tests, discuss the history of intelligence testing, and describe some criticisms of intelligence tests.
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The psychometric approach to studying intelligence attempts to measure intelligence with
carefully constructed psychological tests.
To ensure that intelligence tests are grounded in sound scientific principles, psychologists
design tests that adhere to three basic criteria: standardization, reliability, and validity.
Early pioneers of intelligence testing include Francis Galton, who proposed the theory of
psychophysical performance, and Francis Binet, who developed a test to predict children’s
success in school.
Adapting Binet’s work for use in the United States, Lewis Terman constructed the StanfordBinet Intelligence Test and devised the intelligence quotient (IQ).
David Wechsler broadened the usefulness of intelligence testing by developing the Wechsler
Adult Intelligence Scale (WAIS), along with several other tests.
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Both the Stanford-Binet and the WAIS have high degrees of reliability. Performance on
intelligence tests also correlates highly with school performance, and to some degree with
other areas of functioning in life, such as occupational achievements.
Although widely used, intelligence tests are subject to several criticisms. One issue involves
the culture-specific nature of the tests, which may produce bias. A related problem is
stereotype threat.
Intelligence test scores from around the world have increased over time, a phenomenon
known as the Flynn effect. Possible explanations include potential problems with the
procedures, content, or nature of the tests and improvements in education, nutrition, health,
or environments.
Is Intelligence Governed by Genetic or Environmental Factors?
LEARNING OBJECTIVE 4 Review the contributions of heredity and environment to
intelligence, and explain how emphasizing one factor or the other can affect social policy.
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The nature–nurture debate as applied to intelligence has important social implications,
exemplified by the controversial book The Bell Curve, whose authors argued that group
differences in IQ are likely due at least in part to genetic factors.
Family studies and research in molecular biology have indicated that heredity does play a
major role in intelligence. Researchers estimate that the heritability of intelligence is about 50
percent.
Environmental factors that affect intelligence include family and home, overall culture,
occupation, and schooling.
Group differences in IQ scores enable us only to make distinctions between groups, not to
reach any conclusions about an individual within a group.
Studies have confirmed that environmental enrichment for members of disadvantaged groups
is effective in producing at least short-term cognitive gains.
Intelligence What Happens in the Brain?
LEARNING OBJECTIVE 5 Describe how brain size, number of neurons, processing speed,
brain activity, and cortical thickness relate to intelligence.
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Neuroimaging studies suggest that overall brain size is not correlated with intelligence. The
number of neurons in certain brain regions, such as the frontal lobes, may be related to
intellectual functioning.
The speed with which the brain responds to stimuli, which can be measured by means of
EEGs and nerve conduction velocity (NCV), also correlates with intelligence.
PET scans, which show what areas of the brain are active at a particular moment, have
generally revealed lower activity in the brains of people performing well on an intellectual
task and higher activity in the brains of people performing poorly. This suggests that the
brains of the higher performers may be more efficient.
It appears that the development of intelligence involves a process of neuron growth and then
neuron pruning, particularly in the prefrontal cortex—a process that is reflected by a distinct
pattern of change in cortical thickness throughout childhood and adolescence.
Extremes in Intelligence How We Differ
LEARNING OBJECTIVE 6 Discuss mental retardation and giftedness.
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The two extremes of intelligence, as measured by IQ tests, are represented by mental
retardation and giftedness.
Mental retardation is classified as mild (IQ 50–70), moderate (IQ 35–49), severe (IQ 20–34),
and profound (IQ below 20).
Home environmental causes of intellectual disability include poor and unstimulating
environments and inadequate parent–child interactions. These causes have been associated in
particular with mild retardation, though they may also be at work in more severe cases.
Other causes of retardation include genetically based chromosomal abnormalities, certain
prenatal conditions in the mother, complications at delivery, and injuries and infections
during early childhood. These causes have been associated in particular with moderate to
profound levels of retardation.
Down Syndrome is a genetic abnormality resulting in mental retardation.
Psychologists do not agree on how to define giftedness, but often identify gifted persons as
having IQs at the top 1 or 2 percent of the tested population.
Environment can contribute to giftedness, and gifted people are often highly motivated.
However, academically gifted people may not be equally gifted with social and emotional
intelligence.