Intelligence involves the capacity to learn and adapt to one's environment, and theories of intelligence propose both general factors of intelligence as well as multiple intelligences. Research finds that intelligence is influenced by both genetic and environmental factors, with twin and adoption studies estimating heritability accounts for 30-75% of differences in intelligence. Larger brain size is correlated with higher intelligence, and environmental factors like education and nutrition can also impact intellectual development.
1. CHAPTER 11: INTELLIGENCE
• Introduction
• Intelligence testing
• Theories of intelligence
• Heredity and environment
• Size does matter!
2. Introduction
• According to Sternberg (2004, p. 472),
intelligence involves “the capacity to learn from
experience and adaptation to one’s
environment.”
• We need to pay attention to cultural differences.
• What is needed to adapt successfully in one
environment may be very different from what is
required in another environment.
• Individualistic vs. collectivistic.
3. In Zimbabwe, the word for intelligence is
ngware. What does this mean?
• a) Be able to find your way in a new
environment
• b) Do well in school
• c) Be able to play a musical instrument
• d) Be careful and prudent in social
relationships
• e) Be independent
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4. Emotional Intelligence
• Defined as “the ability to monitor one’s own and others’
emotions, to discriminate among them, and to use the
information to guide one’s thinking and actions.”
• Most early research on emotional intelligence made use of
self-report questionnaire measures.
• Emotional Intelligence Inventory
• Davies, Stankov, and Roberts (1998) carried out several
studies to find out what is being measured by questionnaire
measures of emotional intelligence.
• They found that measures of emotional intelligence were
unrelated to intelligence assessed by IQ tests.
5. Emotional Intelligence
• Mayer, Salovey, and Caruso (2002) developed an
Emotional Intelligence Test (MSCEIT) based on the
notion that that four main abilities underlie emotional
intelligence:
• Perceiving emotions: identification of emotion in oneself and in
others (e.g., identifying facial emotions).
• Using emotions: facilitating thought and action through
experiencing the optimal emotion.
• Understanding emotions: the ability to comprehend the
language of emotion and to make sense of complicated
relationships among emotions.
• Managing emotions: regulation of emotion in oneself and
others.
6. Emotional Intelligence
• Findings from use of the MSCEIT:
• Small to moderate correlations with intelligence and
personality factors.
• It predicted deviant behavior in male adolescents.
• High scores were rated as more positive for
personality qualities.
• Heterosexual couples with high scores were happier
than those with low scores.
• Employees with high scores were rated as being
better (easy to deal with, sociable, leaders, more
promotions).
7. Evaluation
• Emotional intelligence is of real importance and deserves to be the
focus of research.
• Traditional approaches to intelligence are somewhat narrow, and an
emphasis on emotional intelligence serves to broaden intelligence
research.
• The MSCEIT is a reasonably promising measure of emotional
intelligence.
• Most self-report questionnaire measures of emotional intelligence are
seriously deficient, and assess mainly well-established personality
dimensions.
• There is little evidence that any measures of emotional intelligence
predict job performance or success over and above that predicted by
pre-existing ability and personality measures.
• More research is needed to establish that emotional intelligence is
actually an important type of intelligence.
8. Practical Importance
• There is convincing evidence that intelligence is very important
in everyday life.
• For example, job performance and academic achievement
among students are both moderately well predicted by
intelligence or IQ (Mackintosh, 1998).
• Hunter and Hunter (1984) considered over 32,000 workers
performing 515 different jobs.
• They identified five levels of job complexity.
• The average correlations between intelligence and job performance
were as follows: +.58 for professional jobs, +.56 for complex
technical jobs, +.51 for medium-complexity jobs, +.40 for semi-
skilled jobs, and +.23 for unskilled jobs.
9. Practical Importance
• Hunter (1983) studied four very large samples of military
personnel undergoing job training programs.
• In all samples, intelligence strongly predicted training
performance and specific aptitude or ability scores.
• Why is there is a strong association between intelligence and
job performance?
• There is a moderate correlation between intelligence and
socioeconomic status (Mackintosh, 1998).
• Murray (1998): siblings with higher intelligence had more
prestigious jobs and higher incomes.
• Hunter and Schmidt (e.g., 1996) argued that the ability to learn
rapidly is of crucial importance in most jobs, and learning ability is
determined by intelligence.
10. Health and Longevity
• Individual differences in intelligence also predict health and
longevity (Gottfredson & Deary, 2004).
• Whalley and Deary (2001) found that individuals at a 15-point
disadvantage in IQ relative to other individuals were only 79%
as likely to live to age 76.
• Among the women, the less intelligent ones had a 40%
increase in cancer deaths compared to the more intelligent
ones, and the comparable figure for men was 27%.
• More intelligent individuals have greater health literacy than
less intelligent ones.
11. Intelligence Testing
• Alfred Binet and Theodore Simon (1905):
• The first proper intelligence test.
• Measured comprehension, memory, and various
other psychological processes.
• Other tests that followed are the Stanford-Binet test,
the Wechsler Intelligence Scale for Children, and the
British Ability Scales.
12. Calculating IQ
• Tests are often used to calculate the person’s IQ, which
means that the individual’s score is compared to scores
obtained by other people taken from a standardized
sample.
• Most IQ tests are designed to produce scores that are
normally distributed—a bell-shaped curve, with the mean
IQ being 100 and the standard deviation being about 16.
• This allows psychologists to determine the percentage of
the population above or below an individual’s IQ score.
13. Standardized Tests
• Given to a large representative sample.
• Age groups.
• Compare an individual’s score against the
scores of other people.
• Intelligence quotient (see next slide).
• Various abilities:
• Numerical
• Spatial
• Reasoning
• Perceptual speed
14.
15. Reliability
• The extent to which a test provides consistent
findings.
• Reliability is generally assessed by the test–
retest method:
• People take the same test on two separate
occasions.
• The scores of all the participants on the two
occasions are then correlated with each other.
• The higher the correlation, the greater the reliability of
the test.
16. Validity
• The extent to which a test measures what it is
supposed to be measuring:
• Concurrent validity
• Predictive validity
• IQ scores typically correlate:
• +.5 with academic achievement and occupational status.
• Job performance with complex jobs.
17. What term is used to describe an individual's
test score correlating highly with their
academic achievements?
a) Predictive validity
b) Face validity
c) Concurrent validity
d) Construct validity
e) Reliability
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18. Theories of Intelligence
• Factor analysis:
• Giving people a range of tests to see whether the
results of each test correlate.
• Technique enables psychologists to decide whether
the test is measuring one factor or several.
• Can take several forms and this might explain why
psychologists have come up with different factor
theories of intelligence.
19. Factor Theories
• Spearman (1923):
• The first factor theory of intelligence.
• General factor of intelligence, called g.
• Specific factors associated with each test, which he called “s.”
• Thurstone (1938):
• Seven factors (primary mental abilities):
– Inductive reasoning, verbal meaning, numerical ability, spatial ability,
perceptual speed, memory, and verbal fluency.
• Carroll (1993): Hierarchical approach combined the above
into three levels:
• Top: general factor.
• Middle: general factors including fluid ability (nonverbal reasoning),
crystallized ability (knowledge).
• Bottom: specific factors.
20. Which one of the following is NOT one of
Thurstone’s primary mental abilities?
a) Verbal meaning
b) Numerical ability
c) Spatial ability
d) Bodily-kinesthetic ability
e) Perceptual speed
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23. Gardner (1983): Multiple
Intelligences
• Suggested that there might be several other intelligences.
• There were six criteria that he thought were needed to identify
intelligences, including the idea that the intelligence should
depend on identifiable brain structures.
• In an attempt to gain evidence to support his theory Gardner
(1993) undertook a study of geniuses (Freud, Einstein, Picasso,
etc.).
• He found that there were some similarities in the background of
his choice of creative individuals such as being ambitious, having
childlike qualities, and having come from families that imposed
high moral values.
24. Evaluation
• Gardner’s approach to intelligence is broader in scope than most
others.
• There is some supporting evidence (e.g., from geniuses; from brain-
damaged patients) for all seven intelligences originally proposed by
Gardner.
• The seven intelligences correlate positively with each other, whereas
Gardner (1983) assumed they were independent. That means that
Gardner was wrong to disregard the general factor of intelligence.
• Musical and bodily kinesthetic intelligences are less important than the
other intelligences in Western cultures, with many very successful
people being tone-deaf and poorly coordinated.
• The criteria for an intelligence are too lenient.
• The theory is descriptive rather than explanatory—it fails to explain
how each intelligence works.
25. Heredity and Environment
• Heredity consists of a person’s genetic
endowment.
• Environment consists of the situations and
experiences encountered by people in the
course of their lives.
• Our makeup influences the types of
environmental experiences we have.
26. Heredity and Environment
• Plomin (1990) identified three types of
interdependence between genetic endowment
and environment:
• Active covariation
• Passive covariation
• Reactive covariation
• Genotype is an individual’s genetic potential.
• Phenotype is observable characteristics.
27. Why is it difficult to give weightings to both the
genetic and environmental components of
intelligence?
a) It is exceptionally difficult to control all
environmental factors
b) It would be unethical to institute a breeding
program on humans
c) Genetic and environmental factors interact
d) It is difficult to measure intelligence
e) All of these
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28. Twin Studies
• Monozygotic twins
• Identical twins
• Identical genotypes
• Dizygotic twins
• Fraternal twins
• 50% shared genes
• The degree of similarity in intelligence shown by
pairs of twins is usually reported in the form of
correlations.
29.
30. Twin Studies
• Bouchard and McGue (1981)
• Reviewed 111 studies
• Identical twins +.86
• Fraternal twins +.6.
• McCartney et al. (1990)
• Identical twins +.81
• Fraternal twins +.59.
• Identical twins are treated in a more similar fashion
than fraternal twins:
• Prenatal, parental treatment, playing together, dressing in a
similar style, and being taught by the same teachers.
31. Twin Studies: Reared Apart
• Bouchard et al. (1990):
• Identical twins +.75
• This figure is higher than would be expected on an
environmentalist position.
• Environmental factors are also important.
• Identical twins reared apart:
• Brought up in different branches of the same family.
• Separated at age 5.
32. Heritability
• The technical definition of heritability is the ratio of
genetically caused variation to total variation (genetic +
environmental variation) within any given population.
• Heritability is a population measure, and varies considerably
from one population to another.
• Brace (1996) found that the heritability of intelligence was
much higher among people living in affluent white American
suburbs than among people living in American urban
ghettos.
• In essence, the heritability measure combines two kinds of
genetic influence:
• Direct genetic influence
• Indirect genetic influence
33. Heritability
• Mackintosh (1998) reviewed the evidence based
on heritability measures:
• He concluded that between 30% and 75% of
individual differences in intelligence in modern
industrialized societies are due to genetic factors.
• Plomin (1988): the genetic influence on
individual differences in IQ “increases from
infancy (20%) to childhood (40% to adulthood
(60%).”
34. Adoption Studies
• Another way of assessing the relative importance of
heredity and environment in determining differences
in intelligence.
• If heredity is more important than environment,
adopted children’s IQs will be more similar to those
of their biological parents than their adoptive
parents.
• IQs of adopted children typically resemble those of
their biological parents more than those of their
adoptive parents.
35. Adoption Studies
• Selective placement:
• Adoption agencies often have a policy of trying to
place infants in homes with similar educational and
social backgrounds to those of their biological
parents.
• Capron and Duyne (1989)
• Study on adopted children, with no evidence of
selected placement.
• Genetic and environmental factors of about equal
importance in determining the intelligence of the
adopted children.
36. Environmental Studies
• Shared environment:
• The common influences within a family.
• Such as parental attitudes to education and parental income.
• Nonshared environment:
• All those influences that are unique to any given child.
• Twin and adoption studies suggest that about 20% of
individual differences in intelligence are due to
nonshared environment.
37. Flynn Effect
• Flynn (1987, 1994)
• Evidence from 20 Western countries.
• A rapid rise in average IQ in most Western countries in
recent decades.
• An increase of 2.9 points per decade in nonverbal IQ.
• An increase of 3.7 points per decade in verbal IQ.
• Factors:
• Increases in the number of years of education.
• Greater access to information.
• The increased cognitive complexity of the average person’s job.
• A large increase in the number of middle-class families.
38. Sameroff et al. (1993)
• Ten risk factors that accounted for individual differences in IQ:
• Mother has a history of mental illness.
• Mother did not go to high school.
• Mother has severe anxiety.
• Mother has rigid attitudes and values about her child’s development.
• Few positive interactions between mother and child during infancy.
• Head of household has a semi-skilled job.
• Four or more children in the family.
• Father does not live with the family.
• Child belongs to a minority group.
• Family suffered twenty or more stressful events in last 4 years.
• See next slide.
39.
40. Which of the following was NOT one of the risk
factors identified by Sameroff et al (1993) in the
Rochester longitudinal study?
a) Mother has a history of mental illness
b) Father does not live with the family
c) Mother has a full-time job
d) Family suffered 20 or more stressful events
during the child's first year
e) Mother has rigid attitudes about her child's
development
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41. Size Does Matter!
• When psychologists first studied the link between brain
size and intelligence, they found practically no
relationship.
• These early studies were limited because findings were
based on imprecise estimates of brain size (skull size,
measuring the sizes of the shrunken brains of people
who had recently died).
• Today we can obtain good measures of brain size in
living people by using brain-imaging techniques such as
magnetic resonance imaging (MRI).
42. Size Does Matter!
• McDaniel (2005) found the average correlation between
brain size or volume and intelligence was +.33, indicating
that people with larger brains do tend to be more
intelligent.
• The average correlation between brain volume and
intelligence between the sexes was +.40 for females
and +.34 for males.
• There is also evidence from studies on children that
nutritionally enhanced diets produce increases in IQ
(Benton, 2001).
43. Size Does Matter!
• Males vs. females:
• Females have smaller brains than males.
• Possible inference that men are more intelligent than
women does NOT follow—in fact, the two sexes have
essentially the same mean IQ (Mackintosh, 1998).
• Females tend to have greater verbal abilities than
males.
• Males have greater spatial abilities.
44. Size Does Matter!
• There is recent evidence that there may be
important sex differences in brain structures
underlying intelligence.
• Haier et al. (2005) considered two kinds of nerve
tissue in the brain: gray matter and white matter.
• Women had more white matter and fewer gray matter
brain areas related to intelligence than did men.
45. Research has found that females tend to
have ______ abilities than males, and
males have ______ abilities. [Fill in the
blanks.]
a) Greater verbal; greater spatial
b) Greater spatial; greater verbal
c) Lower verbal; lower special
d) Inadequate spatial; no spatiale)
e) Greater verbal; no verbal
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