Testing and Individual Differences
Chapter 11
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What is intelligence?
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Intelligence – ability to learn from experience, solve problems and use
knowledge to adapt to new situations
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Intelligence test – a method for assessing an individual’s mental aptitudes
and comparing them with those of others, using numerical scores
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Charles Spearman (1863 – 1945)
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Believed we have one general intelligence (or g) that underlies specific
mental abilities and is measureable by every task on an intelligence test
Helped develop factor analysis – statistical procedure that identifies
clusters of related items on a test
 Used to identify different dimensions of performance that underlie a person’s
total score
What is intelligence? -cont Raymond Cattell and the Two Subtypes of G
 Broke intelligence down into two relatively independent
components:
 Fluid intelligence – memory, speed of information processing and
reasoning abilities
 Believed fluid intelligence is innate
 Declines with age
 Crystallized intelligence – store of knowledge and skills gained
through experience and education
 Remains stable or increases slightly with age
Theories of Multiple Intelligence
 Howard Gardner’s (b. 1943) theory of multiple intelligences
 Linguistic
 Logical-mathematical
 Musical
 Spatial
 Bodily-kinesthetic
 Intrapersonal
 Interpersonal
 Naturalist
 Better explains savant syndrome – condition in which a person
otherwise limited in mental ability has an exceptional specific skill
Multiple intelligences -cont Robert Sternberg’s three intelligences – believed each was learned
 Analytical intelligence – logical reasoning skills that include analysis,
evaluation and comparison; assessed by intelligence tests
 Creative intelligence – imaginative skills that include developing new
inventions and seeing new relationships
 Practical intelligence – “street smart” skills that include coping with
people and events
 Emotional intelligence – ability to perceive, understand, manage and
use emotions
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Does not include self-esteem or optimism
Some psychologists feel this is stretching intelligence too far
Comparing Theories of Intelligence
Intelligence and the Brain
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Intelligence modestly correlates with brain
size but the cause is unclear
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Highly educated people die with more
synapses
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Higher intelligence scores have been
linked to more gray matter in areas
involved in memory, attention and
language
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Verbal intelligence scores are predictable
from the speed people retrieve
information from memory
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Brain waves of highly intelligence people
register a simple stimulus faster and with
greater complexity
Assessing Intelligence
 Alfred Binet- early 1900s
 Goal was to measure a child’s mental age – chronological age that most
typically corresponds to a given level of performance
 Average 9-year-old has a mental age of 9
 Lewis Terman - extended Binet’s work to develop the Stanford-Binet
intelligence test
 William Stern used these to develop the intelligence quotient (IQ) –
ratio of mental age to chronological age, multiplied by 100
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Modern IQ tests assign the average performance for a given age a score
of 100
2/3 of test takers fall between 85 and 115
Assessing Intelligence -cont Achievement tests – tests designed to assess what a person has
learned
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AP test
 Aptitude tests – tests designed to predict a person’s future
performance
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SAT
 Wechsler Adult Intelligence Scale (WAIS) – most widely used
intelligence test
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Produces a single IQ score but calculates how far a person’s score
deviates from scores of others in the same group and plotted on a bell
curve
Principles of Test Construction
 To be widely accepted, psychological tests must show
 Standardization – defining meaningful scores by comparison with the
performance of a pretested group
 Should be distributed in a normal curve – symmetrical, bell-shaped
curve; most scores fall near average with fewer near the extremes
 68% fall within one standard deviation above or below the mean
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Reliability – extent to which a test yields consistent results – can be
determined through:
 Test-retest method – researchers compare participants’ scores on two
separate administrations of the same test
 Split-half method – test is divided into two equivalent parts and
researcher determines degree of similarity between scores on the two
halves of the test
Principles of Test Construction -cont Validity – extent to which a test measures or predicts what it
is supposed to
 Content validity – extent to which the test samples the
behavior that is of interest
 Predictive (or criterion) validity – success with which a
test predicts the behavior it is designed to predict
 Assessed by computing the correlation between test scores and
criterion behavior
The Normal Curve
Dynamics of Intelligence:
Stability or change?
 Except for the extremes,
casual observation and
intelligence tests before age
3 only modestly predict
future aptitudes
 Intelligence tests begin to
predict adolescent and adult
scores by age 4 and stabilize
after age 7
Intelligence Endures
The Dynamics of Intelligence:
The extremes
 The Low Extreme
 Intellectual disability – a condition of limited mental ability
indicated by an intelligence score of 70 or below and difficulty in
adapting to the demands of life
 Varies from mild to profound
 The High Extreme
 Tracking by aptitude may produce a self-fulfilling prophecy –
those labeled as “ungifted” may be influenced to become so
 Can also promote segregation and prejudice
Degrees of Intellectual Disability
The Nature vs. Nurture of Intelligence
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50-75% of intelligence test score variation can be attributed to genetic
variation
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Intelligence scores of identical twins raised together are almost as similar as
the same person taking the test twice
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Scores of fraternal twins are much less similar
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Adoption enhances the intelligence scores of mistreated or neglected
children
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Mental similarities between adopted children and their adoptive families
decrease with age
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Among the poor, environmental conditions can override genetic differences
Intelligence: Nature and Nurture
Who do adopted children resemble?
Bias and Intelligence
 Stereotype threat – self-confirming concern that one will be
evaluated based on a negative stereotype
 Blacks have scored higher when tested by Blacks than when
tested by whites
 Women score higher on math tests when no male test-takers are
in the group