Intelligence & Intelligence
Testing
Psychometrics is a very sophisticated field
which uses applied mathematics to measure
psychological and behavioral attributes and
make predictions. Psychometricians
construct, standardize, validate tests. Many
people who criticize tests do not understand
test theory or the mathematics behind test
construction.
Types of Reliability
Type
Description
 Test-Retest
Test produces similar results when given at two
points in time.
Two versions of the same test produce similar
results.
Different parts of the same test produce similar
results.
Two or more raters or judges who administer
and score a test to an individual come to similar
conclusions.
 Alternate Form
 Internal
 Interrater or
Interjudge
Types of Validity
Type
 Face
Description
 Content
Test assesses all important aspects of
phenomenon.
 Concurrent
Test yields the same results as other
measures of the same behavior, thoughts or
feelings.
 Predictive
 Construct
Test appears to measure what it is supposed
to measure.
Test predicts the behavior it is supposed to
measure.
Test measures what it is supposed to
measure and not something else.
The Psychometric Approach
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How do you define “Intelligence”?
Theorists use narrow, operational
definitions
Psychometricians do not claim that what is
measured by an intelligence test is a good
representation of “real-world” intelligence
which is a broader concept
Is it useful?
Wechsler’s definition
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Intelligence is the aggregate or global
capacity of the individual to act
purposefully, to think rationally, and to deal
effectively with the environment.
Theories of Intelligence
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Spearman – g factor & s factor
Cattell – crystallized and fluid intelligence
Gardner – 8 separate “intelligences”
Sternberg – triarchic theory of intelligence
Contextual
 Experiential
 Componential
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Does “g” exist?
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One of the longest-running debates in
psychology:
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global intelligence, a general ability
specific abilities
…..More a matter of emphasis
“Intelligence is what intelligence tests measure”
Edward Boring
Invention of IQ Tests
Sir Francis Galton – published Hereditary
Genius in 1869 – believed that “eminence”
ran in families (genetic).
- interested in studying “eminence” (and
presumably intelligence – established a
number of anthropometric laboratories.
- measured eyesight, reaction time
- related to his cousin Charles Darwin’s
idea of “species’ fitness”
Invention of IQ Tests
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Alfred Binet: 1904
Mental Age
Theodore Simon
Lewis Terman: 1916
Stanford IQ
Divided child’s mental age by the
child’s chronological age to yield an
Intelligence Quotient (IQ) (idea originally
from William Stern, a German psychologist)
All average children, regardless of age,
would have an IQ of 100
Binet Test comes to America
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Lewis Terman revised Binet’s test
Devised norms for American kids
Stanford- Binet Intelligence Scale: 1916
Been updated many times
David Wechsler: Wechsler Adult
Intelligence Scale (WAIS) (WISC)
---Probably the best IQ test for adults
---Different subscales (Verbal vs..
Performance)
“He had a WAIS IQ of …..”
Intelligence Measured
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Most popular and most frequently administered
are the Wechsler Scales
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Wechsler Adult Intelligence Scale (WAIS III)
WAIS-R as a Neuropsychological Instrument (WAISRNI)
Wechsler Intelligence Scale of Children (WISC-IV)
Wechsler Primary and Preschool Scale-Revised
(WPPSI-R)
Stanford-Binet V
Kaufman Assessment Battery
Woodcock-Johnson Psychoeducational Battery
III
Wechsler system
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Verbal subtests
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Information
Similarities
Arithmetic
Vocabulary
Comprehension
Digit span
Letter-number sequencing
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Performance subtests
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Picture arrangement
Picture completion
Block design
Object assembly
Matrix reasoning
Digit symbol
Symbol search
Wechsler System
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Mean score of 100; SD of 10 (15 in WISC and WPPSI)
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90-110 average range
< 70 is in mentally deficient range
> 130 is in the very superior range
Individual tests have a mean score of 10; SD of
3
All form the basis for subtle observations about
relative strengths and limitations
Observe patterns of scores
Interpreted in the context of other test results
and variety of biopsychosocial factors
Correlations in IQ
Henderson, 1982
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Relationship
pairs
r
# of
Individual with self:
MZ twins
.87
.86
456
1417
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MZ apart
DZ twins
Siblings
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Sibs apart
.75
.62
.41
1329
5350
.21
203
IQ tests cont.
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Today’s tests based on norms rather than
MA
Average is still set at 100
SD usually 15
2/3 score between 85 and 115
New uses in America
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Binet thought the tests could be useful for
identifying children with learning problems--not
to rank normal children
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In America, the original purpose was lost
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The tests came to be used to categorize people
in school and in the armed services according to
their “natural ability”.
Army alpha
 Army beta (no English required)
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Intelligence testing
Arguments for
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reliable measure of individual differences –
important for identifying need, allocating
resources
reliable predictor of school achievement
identify discrepancies between expected and
actual performance
allow for accountability, measurement of
change and evaluation of program
effectiveness
IQ tests
Arguments against
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measure samples of behavior , i.e. are not
exhaustive
not theory driven – less true now
potential for cultural, SES bias
IQs change, reflecting both measurement
error + actual performance differences
different tests yield different IQs
not a magical manifestation of a child’s innate
potential