Intelligence and
Individual Testing
Differences
AP Psychology, Myers Chapter 10
Intelligence
 Intelligence: mental quality consisting of the ability to
learn from experience, solve problems, & use knowledge
to adapt to new situations.
 Intelligence Test: method for assessing an individual’s
mental aptitudes & comparing them with those of others
using numerical scores.
 General Intelligence (g): coined by Charles Spearman
(1863-1945.
Found that individual’s scores on various intelligence
tests correlated with one another (if you did well in one
aspect of intelligence, you did well on other tests of
intelligence.
Intelligence (cont’d)
Single Factor Intelligence Theory:
• Determined that one factor g, underlies all
intelligence & is therefore measured by every task on
an intelligence test
• Also identified the s factor that was important for
special abilities.
Spearman also helped to develop factor analysis:
statistical procedures that identifies clusters of related
items (factors) on a test; also used to identify different
dimensions of performance that underlie a person’s
total score.
Spearman’s work was disputed by Louis Thurstone who
used factor analysis to examine tests of college
students.
Intelligence (cont’d)
Identified 7 distinct factors he termed primary mental
abilities which included:
-- inductive reasoning, word fluency, perceptual
speed, verbal comprehension, spatial visualization,
numerical ability, & associative memory.
 John Horn & Raymond Cattell determined that Spearman’s
g should be subdivided into two factors of intelligence –
fluid intelligence: general ability to think abstractly,
reason, identify patterns, solve problems, and discern
relationships, declines with age
crystallized intelligence: store of knowledge gained
through experience & education, peaks later in life
Multiple Intelligences
 Howard Gardner: Theory of Multiple Intelligences
 Savant Syndrome: individuals otherwise considered
cognitively challenged, have a specific exceptional skill
typically in calculating, music, or art
-- savants were an indication to Gardner that a single g
factor did NOT underlie intelligence.
 Believe in the existence of 8 intelligences
• Three are measured on traditional intelligence tests:
logical-mathematical, verbal-linguistic & spatial
• Five are not: musical, bodily-kinesthetic, naturalistic,
intrapersonal, & interpersonal. According to Gardner,
these abilities also represent ways people process
information differently.
 Gardner’s theory has led to changes in how some
schools classify gifted and talented children for special
programs.
Multiple Intelligences (cont’d)
Triarchic Theory of Intelligence (Robert Sternberg)
 Three distinct intelligences that include:
 Analytical Thinking: compare, contrast, analyze, &
figure out cause and effect relationships
 Creative Intelligence: evidenced by adaptive reactions
to novel situations, showing insight, and being able to
see multiple ways to solve a problem.
 Practical Intelligence: includes “street smarts” such as
being able to read people, being able to get to a distant
location or organizing an event. (also known as
emotional or interpersonal intelligence)
• Such people with practical intelligence often succeed in
careers, marriages, & parenting, where people with
higher IQ but less emotional intelligence fail.
Creativity
 defined as the ability to generate ideas and solutions that are
original, novel, and useful, not usually measured by
intelligence tests.
 Sternberg & colleagues identified 5 components of creativity:
 Expertise: a well developed base of knowledge
 Imaginative thinking skills: provide the ability to see
things in novel ways, recognize patterns & to make
connections.
 Venturesome personality: seeks new experiences,
tolerates ambiguity & risk, perseveres in overcoming
obstacles.
 Intrinsically motivated: driven more by interest,
satisfaction & challenge than by external factors.
 Creative environment: sparks. Supports, & refines creative
ideas.
Multiple Intelligences (cont’d)
Emotional Intelligence (Salovey & Mayer)
 The ability to perceive, express, understand, & regulate
emotions.
 Combines Gardner’s interpersonal & intrapersonal
intelligences
 MEIS Multifactor Emotional Intelligence Scale (Salovey,
Mayer, & Caruso): developed to measure emotional
intelligence
Intelligence & Brain Anatomy
 Some studies have found a
positive correlation between
intelligence score, brain size,
& activity, particularly in the
frontal & parietal lobes.
 There appears to be more
grey matter (cell bodies found
in convolutions) & white
matter (axons that lead to all
regions of the brain) to
enable high connectivity
among regions of the brain.
 People who score high on
intelligence tests tend have
more agile brains that score
high in speed of perceptions
& speed of neural processing.
History of Intelligence Testing
 Francis Galton (1822-1911): Measurement of
Psychophysical Performance
 Believed that intelligence was inherited
measured psychomotor tasks to gauge intelligence
 reasoned that people with excellent physical abilities are
better adapted for survival and therefore highly intelligent.
Failed in his attempt to construct a simple intelligence test
Provided us with the phrase – nature and nurture!
 James McKeen Cattell brought Galton’s studies to the US,
measuring strength, reaction time, sensitivity to pain, &
weight discrimination – collectively called “mental test”
 Correlated poorly with reasoning ability, but brought
attention to the systematic study of measuring cognitive &
behavioral differences.
Modern Intelligence Testing
Movement
 Alfred Binet: Measurement of Judgment
 thought intelligence could be measured by sampling
performance of tasks that involved memory, comprehension
& judgment.
 Collaborated with Theodore Simon to create the Binet-Simon
Scale which was meant to only be used for class placement.
 Binet believed that child the age of 6 answers questions
differently that a child of 8, so based on responses on the
Binet-Simon Scale, children were given a mental age (mental
level) reflecting the age in which typical children give those
same responses.
 Because mental age could be misleading, William Stern
(German psychologist) suggested using the ratio of mental
age (MA) to chronological age (CA) to determine a child’s
intelligence.
Intelligence Quotient
 Mental Age and Intelligence Quotient
 Lewis Terman adapted Binet’s scale for the US, calling
it the Standford-Binet Intelligence Scale
 The scale score is reported as IQ, which is the child’s
MA/CA X 100.
Practice: what is the IQ of a 4 year old child with a
mental age of 6?
150
During this time, intelligence tests were sometimes
used to document scientists’ assumptions about the
innate inferiority of certain ethnic & immigrant groups
Tests of Mental Abilities
 Achievement Tests: designed to assess what a person has
learned .
 Examples include a literacy test, a driver’s license exam,
and a final exam in a psychology course.
 Aptitude Tests: designed to predict a person’s future
performance where aptitude is defined as the capacity to
learn.
 The SAT, ACT, and GRE are supposed to predict your ability to do
well in future academic work
As an aptitude test, the
SAT does correlate well
with intelligence, but is
it truly predictive of
future academic
performance?
The Wechsler Intelligence Scales
 David Wechsler developed the most widely used age based
intelligence tests including:
 WPPSI (Wechsler Preschool & Primary Scale of Intelligence)
WISC (Wechsler Intelligence Scale for Children 6-16)
 WAIS (Wechsler Adult Intelligence Scale for older adolescents and
adults)
 WAIS-III has 15 subsets including:
o a verbal scale with items on comprehension, vocabulary,
information
o similarities, arithmetic, and digit span
o performance scale with items
dealing with object assembly,
block design, picture completion,
picture arrangements, & digit
symbols.
Block Design
68% of the population has an IQ between 85 and 115
(considered low normal to high normal in intelligence)
Extremes of Intelligence
Intellectual
Disability
Gifted
Intelligence
The Wechsler Intelligence Scale is set so that about 2% of
the population is above 130 and about 2 % of the
population is below 70.
Extremes of Intelligence
 Intellectual Disability: People who fall 2 SD (standard
deviations) below the mean (70); those who score 2 SD
above the mean (130) are sometimes considered
mentally gifted.
 Those with scores 3 SD above the mean (145) are
sometimes considered to be geniuses.
 These scales are judged to be more helpful to determine
extremes of intelligence than the Standford-Binet Scale.
 They also are helpful in identifying possible learning
disabilities when a child’s performance IQ is very
different from his/her verbal score.
Extremes of Intelligence
(cont’d)
 Mildly cognitively disabled individuals score between 50 to
70 on IQ tests and are usually capable of taking care of
themselves, their homes, achieve a 6th grade education,
hold a job, get married and have children.
Such children are often mainstreamed (integrated into
regular education classes)
 Moderately cognitively impaired individuals score between
35-49 on IQ exams, may achieve a 2nd grade level, given
training in skills such as eating, toileting, hygiene,
dressing, and grooming in order to care for themselves,
and given life skills training so they can hold down menial
jobs and live in group homes.
Extremes of Intelligence (cont’d)
 Severely cognitively challenged individuals have scores
or 20-34 on IQ tests, have a limited vocabulary, and learn
limited self-care skills. They are usually unable to care for
themselves and do not develop enduring friendships.
 Profoundly mentally challenged individuals with IQ
scores below 20 need custodial care.
 Today, communities are housing a greater proportion of
cognitively disabled people than in the past.
Many live with their own families or in group homes
when possible.
 This deinstitutionalization is called normalization.
Standardization & Norms
 Psychometrics: the measurement of mental traits,
abilities, & processes.
 Psychometricians: involved in test development in
order to measure some CONSTRUCT or behavior that
distinguishes people from one another.
Constructs: ideas that help summarize a group of
related phenomena or objects
 Constructs are useful for understanding, describing,
& predicting behavior.
 Psychological tests measure abilities, interests,
creativity, personality, & intelligence.
Standardization & Norms (cont’d)
 Standardization: two part test development procedure:
 First, establishes test norms from the test results of a
large representative sample
 Ensures that the test is both administered & scored
uniformly for all test takers
 Norms: scores established from the test results of the
representative sample and used as a standard to
compare scores of other test takers.
 When administering a standardized test, all proctors
must provide the same directions, time limits, &
conditions as other proctors. Scorers must use the
same scoring system, applying the same standards to
rate responses.
Standardization & Norms (cont’d)
 Re-Standardization: Re-testing a sample of the general
population to make an updated, accurate comparison
group, in case people are smarter than they used to be
when the test was first made.
The Flynn Effect:
Performance on
intelligence tests
has steadily
improved over the
years worldwide.
What factors do you
think can account
for this effect?
Reliability & Validity
 Reliability: consistency of test results over time
(repeatability) as long as all other variables remain the
same.
 Test-retest method: the same exam is administered to
the same group on two different occasions & the scores
are compared.
• the closer the coefficient is to 1, the more reliable
the test
• Problem: familiarity when taking the test for the
second time may skew results.
 Spilt-half method: the score from the first half of the
test is compared to the score on the last half of the test
to see if they are consistent.
Reliability & Validity (cont’d)
 Alternate form method (equivalent form method): two
different versions of a test on the same material are
given to the same test takers, and the scores are
correlated.
 Inter-rater Reliability: the extent to which two or more
scorers evaluate responses in the same way.
 Validity: the test accurately measures or predicts what it
is supposed to measure.
 Face Validity: measure of the extent to which the
content of the test measures all the knowledge and/or
skills that are supposed to be included within the
domain of that test, according to the test takers.
Reliability & Validity (cont’d)
 Content Validity: the extent to which a test samples the
behavior that is of interest
Predictive Validity: a measure of the extent to a test
predicts the behavior it is designed to forecast.
o Ex: high SAT scores should predict high grades for
the first year of college.
 Construct Validity: the extent to which the test actually
measures the hypothetical construct or behavior it is
designed to test. Often considered the true measure of
validity.
Types of Tests
Performance Tests
 Include SATs, AP tests, Wechsler Intelligence tests,
Stanford-Binet intelligence tests, and most classroom
tests.
 The test-taker knows to do in response to questions or
tasks. It is assumed that the test taker will do the best
he/she can do to succeed.
 Speed Tests: include a large number of relatively
easy items administered with strict time constraints
under which most test takers find it impossible to
complete.
 Power Tests: provide the test taker with enough time
to complete items of varying difficulty. Differences in
scores among test takers reflect knowledge &
perhaps good guessing.
Types of Tests (cont’d)
Self-Report Tests
 require the test taker to describe his/her feelings,
attitudes, beliefs, values, opinions, physical &/or mental
state on surveys, questionnaires, or polls. Includes
personality tests
Observational Tests (employment interview, & formal onthe-job observations for evaluation)
 The test-taker does NOT have a single well-defined task
to perform. Assessed on typical behavior or performance
in a specific context.
 Interest Tests: used a person’s descriptions of his/her
own interests to predict vocational adjustment and
satisfaction
 Strong-Campbell Interest Inventory: most widely used
vocational interest test
Types of Tests (cont’d)
 Group Tests: test many people at once; the test taker
works alone. These tests are cheaper to administer and
more objective in scoring.
 Examples include SAT, ACT, AP exams
 Individualized Tests: interaction of one examiner with
one test takers. Such tests are expensive and involved
subjective grading.
 Examples include Wechsler Adult Intelligence Scale-III
and Standford-Binet Intelligence Scales
Ethics & Standards in Testing
 The American Psychological Association (APA) & other
guidelines detail standards to promote the best
interests of the client, guard against misuse, and
respect the client’s right to know results and safeguard
dignity.
 Culture-relevant tests: test skills and knowledge
related to cultural experiences of the test takers.
Stability of Intelligence
Scores across the Lifespan
 Fluid Intelligence: our ability to reason speedily &
abstractly tends to decrease in the 20s & 30s slowly up
to age 75. From there is begins to decrease rapidly.
 Crystallized Intelligence: our accumulated knowledge &
verbal skills, tends to increase with age.
Word power
increases with
age
Stability of Intelligence
Scores across the Lifespan
 By the age of 4, a child’s performance on intelligence
tests begins to predict their adolescent & adult scores
Based on the
results of a
longitudinal
study depicted in
this chart, does
intelligence test
score at age 11
predict
intelligence test
score at age 80?
Heredity/Environment &
Intelligence
 Down’s Syndrome: cognitive impairment from genetic
defects (nature)
 FAS (Fetal Alcohol Syndrome): mental retardation of
child as a result to prenatal exposure to alcohol
(primarily environmental)
 PKU (Phenylketonuria): cognitive disability due to both
nature and nurture
 Cultural-Familial Retardation: About 75% of all cases of
cognitive impairment result from sociocultural
deprivation in an impoverished environment
Twin Studies
 Studies to gauge the influence of genes on intelligence
including comparing the intelligence test scores of
identical twins reared together with scores from
fraternal twins.
 Such studies show that identical twins have much
higher scores.
 Even when reared apart, identical twins evidence
similar intelligence score that even closer with age.
 Intelligence scores of adoptees are more similar to
their biological parents than adopted parents & become
more similar with age.
 Brain scans of identical twins reveal similar brain
volume & anatomy.
Environmental Influences on
Intelligence
 Siblings raised together are more similar in IQ than those
raised apart.
 The IQs of children from deprived environments who
move into middle or upper-class foster or adoptive
families tend to show increases.
 Heritability: for intelligence for individuals ranges from
50-75%. (proportion of variation among individuals in a
population that results from genetic causes).
 Reaction Range Model: genetic makeup determines the
upper limit for an individual’s IQ; the lower limit results
from an impoverished environment.
Gender and Intelligence Scores
 Males & females tend to have the same average
intelligence scores.
 However, they differ in some specific abilities:
 Girls are better spellers, more verbally fluent, better at
locating objects, better at detecting emotions, more
sensitive to touch, taste, & color & outperform boys on
math computations.
 Boys outperform girls at spatial ability & related math. Boys
also outnumber girls at the low & high extremes of mental
abilities.
Human Diversity
 Racial differences in IQ scores indicate that African
Americans, Native Americans, and Hispanic
Americans typically score 10-15 points below the
mean for Caucasian American children.
 Researchers suggests that differences between the
mean scores of two different groups could be caused
entirely by environmental factors.
 Stereotype Threat: part of the difference in IQ scores
may be attributed to the anxiety that influences
members of a group concerned that their performance
on a test will confirm a negative stereotype.