Intelligence Testing
1
2
A brief history of intelligence
• The concept of 'intelligence' is relatively
new, unknown a century ago, though it
comes from older Latin roots
–
inter= between, within + legere =to bring
together, gather, pick out, choose, catch up,
catch with the eye, read; intellegere = to see
into, perceive, understand
• Francis Galton revived the term in the
late 19th century, arguing for its
innateness
3
A brief history of intelligence
• Some objected to the innateness bias, and
suggested the term be replaced with
'general scholastic ability' or 'general
educational ability'
• However, this did not catch on = most
theorists today posit a construct of
intelligence that is independent of
education
4
Defining intelligence
Binet (1916) defined it as the capacity to judge well,
to reason well, and to comprehend well
Terman (1916) defined it as the capacity to form
concepts and grasp their significance
Pintner (1921) defined it as the ability of an
individual to adapt well to new situations in life
Thorndike (1921) defined it as the power of good
responses from the point of view of truth or fact
Thurstone (1921) defined it as the capacity to inhibit
instinctive response, imagine a different response,
and realize the response modification into
behavior
5
Defining intelligence
Spearman (1923) defined it as a general ability involving mainly
the ability to see relations and correlates
Wechlser (1939) defined it as the global capacity of an
individual to act purposefully, think rationally, and deal
effectively with the environment
Piaget (1972) defined it as referring to the superior forms of
organization or equilibrium of cognitive structuring used for
adaptation to the to the physical and social environment
Sternberg (1985) defined it as the mental capacity to
automatize information processing and to emit contextually
appropriate behavior in response to novelty
Gardner (1986) defined it as the ability to solve problems or
fashion products valued within some setting.
6
Defining intelligence
• You can take your pick of definitions but
most agree that intelligence has to do with
the related capacities of:
i) Learning from experience
ii) Adapting to ones environment
• Think of a person lacking either of these,
and you pick out people who seem to lack
intelligence
• Note however that very few formal tests
of intelligence really demand subjects to
do either of these!
7
Defining intelligence
• Factor analystic studies (Sternberg,
1981) of informal views of an 'ideally
intelligent' person capture these
characteristics
– They emphasize practical problem
solving and social competence (the same
thing?) as signs of intelligence, along
with a factor loaded on verbal ability
8
Early History on the Intellectually
Impaired-Era of Extermination
• Prevailing attitude is one of
extermination
• Individuals with disabilities were seldom
allowed to live since physical prowess
was valued and essential for the survival
of the group
9
Prehistoric Time
• abandonment
• murdered
• failure to survive (hard life style)
10
Early Historic Time (1552 B.C.-300 A.D.)
• very few records
• first written reference found in
Egyptian papyrus (Therapeutic Papyrus
of Thebes)
• persons with the most severe disabilities
allowed to survive if able
• many forced to beg for food and
shelter
• occurrence of a disability viewed as
sickness and as a punishment from God
for wrongdoing by the parent
11
Aristotle stated that humans
differ from animals by intellect
alone
there was no concept of
individual differences--and
intellect was noted by man's
ability to speak.
• Therefore if an individual was unable to
speak then s/he was no different than
an animal.
12
Era of Ridicule
• During this 1400 years most of the
attitude of people concerning others
with disabilities was that of ridicule or
neglect.
– Persons viewed with a mixture of fear and
reverence.
13
Middle Ages (300-1350 A.D.)
• Emphasis was on "other" world--little
concern for anything but religion and
one's own soul
• All forms of deviance were seen in
supernatural or superstitious terms
• Mental illness and mental retardation
seen as same condition
14
Renaissance (1350-1700 A.D.)
• During this time attention shifted from
"other world" to man, his nature,
dignity, and senses
• Spirit of curiosity gave birth to
medicine and attempts to improve man's
condition on earth
• Differences in disabilities were noted
but recognized only the severest
disabilities
15
Era of Asylum
• Lasted approximately 100 years
• Concept of equality and the concept of
humanism arose
16
Age of Reason (1700-1800 A.D.)
• Humanism stressed dignity of person
• Phrases were heard such as "all men are
created equal" and "equality,
brotherhood and liberty"
• Individualism instead of Group stressed
• Scientific approach was first used with
problems relating to disabilities (e.g.,
MR)
17
1800's
• Era of Education
• Time when mass education became
emphasis instead of education of the few
– grew out of 1700's concern for enlightenment
and individual worth
• During the movement for training
industrialization shifted man's work to
machines; education became very
important
18
Movement for Training (1800-1890)
• Society became aware of the "slow
learner"
• Period of optimism-education seen as a
"cure"
• Significant people:
– Louis Braille
– Edouard Seguin
– Guggenbuhl (1940's)
19
Era of Indictment
• Late 1800's is period of disillusionment
and pessimism
• Recognize the fact that there is no
"cure" for mental retardation
• Research of time indicated that MR and
other behavior disorders were prime
factors in crime and degradation in
country
20
1900's
• time of Measurement (1890-1919 A.D.)
• first mental test was devised (Cattell)
• first special class was founded in the U.S.
in Providence, RI in 1896
• first program to prepare special education
teachers developed at NY University
(1906)
• Significant people:
– Maria Montessori
– Lewis Terman
21
Time of Social Control (1900-1930)
• publication of 1912 research study of
the Kallikak family by Goddard States
• era overlapped the Era of Measurement
and Social Control
22
History of Intelligence Testing
1.
Head Circumference (Francis Galton
1880) – first attempts to measure
intelligence
2. Binet-Simon (Alfred Binet 1909) – first
“intelligence test”
–
–
–
comissioned by French gov to separate
children into vocational vs academic
schooling
did not design test to measure ‘intelligence’
created concept of mental age (MA)
23
Psychological Measurement
th
in the 19 Century
• Interest in science and measurement
• Emergence of psychology as an
experimental and quantitative
science
• Interest in hereditary and
neurological (“measurable”) basis of
cognitive abilities (Galton)
24
History of Psychological Testing
• Basis of psychological testing
– The significance of individual
differences
• Why?
– Interest in performance of
professionals
• Chinese system (2200 BC)
• 19th century Europe
25
Psychological Measurement
th
in the 20 Century
• Public education and availability of
limited funds
• Needs of the military for allocating
personnel (WW I)
26
The History of IQ testing
• First IQ tests developed by Alfred Binet
– Alfred Binet and Theodore Simon
– 30 items of increasing difficulty - 1905
– Revision 1908 – age specific versions
• These were developed to identify children
who needed ‘special’ education
– Binet believed that IQ could be increased by
education
27
The History of IQ testing
• Early IQ tests gave estimate of
children’s MENTAL age by comparing
their performance on various tasks
with performance of children at
various ages
28
The history of IQ testing
• calculated as
• IQ = Mental Age
Chronological age
x 100
Nowadays NORM referenced.. that
is the average performance of a
group is calculated, then individual
comparison
29
Henry Herbert Goddard
• Definition of Intelligence
• "…our thesis is that the chief determiner of
human conduct is a unitary mental process which
we call intelligence: that this process is
conditioned by a nervous mechanism which is
inborn: that the degree of efficiency to be
attained by that nervous mechanism and the
consequent grade of intelligence or mental level
for each individual is determined by the kind of
chromosomes that come together with the union
of the germ cells: That it is but little affected
by any later influences except such serious
accidents as may destroy part of the mechanism"
30
(Goddard, 1920, p. 1).
Henry Herbert Goddard (1866-1957)
• Major Contributions
• Translated the Binet-Simon intelligence scale
into English (1908)
• Distributed 22,000 copies of the translated
Binet scale and 88,000 answer blanks across the
United States (1908-1915)
• Established the first laboratory for the
psychological study of mentally retarded persons
(1910)
• Helped to draft the first American law mandating
special education (1911)
• Strongly argued the hereditarian position
31
Henry Herbert Goddard
32
Stanford-Binet Intelligence Scale
3. Lewis Terman (1916-72) first U.S.
intelligence test
–
–
–
•
Interested in gifted children
translated and modified Binet’s scale
Heavy reliance on vocabulary/language
skills
incorporated old items from the
Binet scale, plus some new items
–
poorly standardized on 1000 children
and 400 adults who were not selected
33
with care
Lewis Terman (1916-72)
–
Developed Intelligence Quotient
IQ = (MA/CA)*100
MA= Mental Age; CA = Chronological Age
34
1916 Stanford-Binet
Sample Items for 12 yr olds
Vocabulary
1. Orange.
45. Sportive.
80. Exaltation.
92. Theosophy
Practical Problem
Solving
Grammar
• FOR THE STARTED AN WE
COUNTRY EARLY AT HOUR
• TO ASKED PAPER MY
TEACHER CORRECT I MY
• A DEFENDS DOG GOOD
HIS BRAVELY MASTER
Interpretation
Similarities
• Snake, cow, sparrow
• Book, teacher, newspaper
• Wool, cotton, leather
Memory
3-1-8-7-9
6-9-4-8-2
5-2-9-6-1
A brief history of intelligence testing
• The 1937 revision of the scale was improved:
– It had wider range (more room on the floor floor and
ceiling)
– It had two parallel forms to permit re-testing
– It was standardized on a carefully selected population, of
100 children in each six-month interval from 6 to 14
years, and 100 in each year from 15 to 18, with control of
sex, selected from 17 different communities
• Alas, they were all white and (therefore) above average
SES
• The test was re-normed in 1960 and 1972, and
revised completely in 1986 (SB-IV)
36
IQ testing in the USA
• In the USA strong supporters of IQ testing
were scientists who believed that IQ is MAINLY
genetic, and that society should breed a superior
group of people
– This is called eugenics
37
3. Army Alpha/Beta IQ Test (1917) –
designed for WWI recruits
–
–
–
Assumed to be testing native
intelligence
Assumed intelligence and literacy
independent
Alpha for literates; Beta for illiterates
and non-English speakers
•
Alpha subtests: Oral Directions; Arithmetic;
•
Beta subtests: Memory; Matching; Picture
Practical Judgment; Analogies; Disarranged Sentences;
Number Series; Information
Completion; Geometric Construction
38
Army Alpha Results by Years of Education
Army Alpha Results by Years of Education
Army Beta Results by Years of Education
S J Gould - A Nation of Morons
• YERKES said that:
– These tests measure
– NATIVE INTELLECTUAL ABILITY
• in other words intelligence
which was unaffected by
culture or educational
opportunities
42
S J Gould - A Nation of Morons
• Gould reports many problems in the
administration of the tests
• Illiterate men were allocated to the Alpha
• The queues for the Beta became so long
that some men were reallocated to the
Alpha
• Many who failed the Alpha were
never recalled
43
S J Gould - A Nation of Morons
• The BETA test still required men to
use pencils and paper - and many had
never been educated at all
• Gould suggests that all the results
should be viewed with scepticism
44
S J Gould - A Nation of Morons
• However the results were used by
the army and had great impact mental testing became…..
– ‘scientifically established’
• by 1921 commercial and
educational establishments
were using the tests
45
Test conclusions
• The average mental age of white
American adults stood at 13 …
• It was possible to grade European
immigrants by their country of origin.
• People of Northern & Western Europe higher than
the Slavs who were higher than people of southern
Europe
• Black people scored lowest of all
• These ‘facts’ were used to provide a
genetic explanation for the differences
46
S J Gould - A Nation of Morons
• Carl Brigham (Yerkes colleague)
• Explained the differences in terms of
racial superiority
• “we notice the Einsteins of the
world BECAUSE they are
exceptional for their Jewish
race”
47
S J Gould - A Nation of Morons
• Why is this not true?
• Immigration from different parts of
Europe took place at different times
– The most recent immigrants scored worse on
the written tests .. If native IQ was being
measured ‘written English should have NO
effect
• Test scores rose with length of stay in the USA
– Those who had been in the USA longer were more
familiar with American customs & products
48
S J Gould - A Nation of Morons
• Brigham
• argued that it was a sign of
intelligence to emigrate to the USA
and that the brightest came sooner!!
• Later immigrants were progressively
more stupid
49
S J Gould - A Nation of Morons
• Despite the evidence IQ tests took
hold
• 1924 US Congress passed the
Immigration Restriction Act
• The Act set quotas for immigration
to the US based on figures 30 years
earlier when immigration from
Southern & Eastern Europe was low
50
S J Gould - A Nation of Morons
• Gould called this • A victory for scientific racism
• During the next 20 years conditions
in eastern Europe worsened for
Slavs and Jews
• The Nazi years
51
S J Gould - A Nation of Morons
• Gould estimates that
• Immigration quotas barred up
to 6 million people from
entering the USA
52
S J Gould - A Nation of Morons
• There is still no good
evidence to suggest that IQ
differences are the result of
genetic differences
53
S J Gould - A Nation of Morons
• There is still no clear
operational definition of
intelligence
• Both race and IQ are political
rather than biological facts
• Socially constructed
54
4. Weschler Intelligence Scale (David
Weschler, 1939-81) – designed to show
subtest scores
–
–
–
–
Less reliant on language/vocabulary skills
Contains Verbal and Performance subtests
Performance compared to same age peers –
raw score has different interpretation
depending on age
Designed widely used test for adults (WAIS),
children (WISC), and preschoolers (WPPSI)
55
WAIS-R Testing kit
Testing Booklet
Puzzle Pieces
Story Cards
Block Design
Other intelligence tests
• There are myriad of other tests of
intelligence including:
– British Ability Scale / Differential Ability
Scale (DAS)
– Peabody Picture Vocabulary Test (PPVT-R)
– Columbia Mental Maturity Scale (CMMS)
– Ravens Progressive Matrices
+ many more
- Some allow group testing, by using closed-choice
formats, allowing for mass screening
58
Matrices Example Item
The IQ Controversy
• On average, African-Americans score 10-15
points lower on IQ tests than Whites
Used by some to argue for superiority of Whites
61
Support for
Genetic Argument
Support for
Environmental Argument
Black kids given IQ tests
in “black English dialect”
still scored 10-15 pts lower
than general White sample
Black kids adopted by middle-class,
college educated White families had
higher average scores than general
Black sample
Black kids matched to
White kids on SES and
family variables still
scored lower on IQ test
Black kids matched to White kids
on SES and family variables scored
much higher on IQ test than general
Black sample
IQ scores of German children raised
out of wedlock did not differ
depending on father’s race
Phenotype (skin darkness) is
correlated with IQ scores, while
genotype (racial ancestry) is not
Conclusion to IQ Controversy
• Difference in scores is not due to bias
in test construction or administration
• Difference in scores is not due to
between group genetic differences
• Difference in scores is partly due to
socio-economic class differences
• Differences may be due to cultural and
“caste” type factors (racism, societal
expectations) - still being investigated
63
Are all intelligence tests
the same?
• Ideally IQ scores obtained with
different instruments should be
identical
• In reality, the instrument makes a
difference: A Wechsler IQ may not
be identical to a Stanford-Binet IQ
– It is important to specify the
instrument
64
Can't we make intelligence
tests the same?
• Distributional characteristics should
make interchanging IQ scores easy
– Alas, intelligence is not perfectly
normal
• there is a hump at the bottom due to many
factors which impinge on intelligence in
early development
• Some have argued that assortative mating
has flattened the distribution (= more very
low and high scores than normal)
65
Does IQ matter?
• Terman & Oden (1959) followed ultra-high
IQ children (IQ > 140) for 40 years
– The gifted children were heavier at birth; walked, talked,
and matured earlier; their general health was better; they
earned more degrees and more money
– However, none went on to become super-successful
Einstein-types
• Some suggested the positive findings might
be due to selection bias, since the initial
selection was based on teacher ratings
• Esquire magazine's "the smartest people in
America"
66
• Marilyn Von Savant and her mistakes
Is IQ innate?
• The literature on IQ heritability is huge
and controversial
• Heritability in IQ has been estimated
between 0.50 and 0.72 (= 50% - 72% of
variability is due to genes)
• The best evidence comes from twin studies
(ie. Bouchard, 1984)
– IQ of identical twins reared apart (even in very
different circumstances) correlate almost as
high as those of identical twins reared together
– Honzik (1957) showed almost no correlation
between IQ of adopted children and IQ of their67
adoptive parents
Is IQ due to environment?
• However, children reared under conditions
of little human contact can show huge
improvements (30-50 IQ points) after
being placed in normal environments
• Jensen (1977) tested the hypothesis of
cumulative effects of environmental
disadvantage, hypothesizing that older
deprived children should do worse on IQ
tests than their younger siblings
– He found some support for this hypothesis- about 1 point per
year for ten years between 5 and 16 years of age, estimated to
be higher if earlier years were included
– Disadvantaged adoptees into advantaged homes often outperform their pre-adoptive peers (Scarr & Weinberg, 1983)
68
Is IQ due to environment?
• A purely innate general intelligence should be
stable over generations
• Intelligence is not stable
• Standardization samples major IQ tests between
1932 and 1981 tended to be higher than their
predecessors
– Overall, humankind appears to have picked up nearly 14
IQ points in the last century
– Similar observations have been made in other countries
using other tests
[ However, note that this does not seem to have stopped
humankind from engaging on a huge scale this century in
some dangerously stupid behaviors…]
69
Is IQ due to environment?
"…psychologists should stop saying that IQ tests
measure intelligence. They should say that IQ
tests measure abstract problem-solving ability
(APSA), a term that accurately conveys our
ignorance. We know that people solve problems on
IQ tests; we suspect that those problems are so
detached, or so abstracted from reality, that the
ability to solve them can diverge over time from
the real-world problem solving ability called
intelligence; thus far we now little else."
Flynn, J.R. (1987). Massive IQ gains in 14 nations:
What IQ tests really measure, Psychological Bulletin,
101, 88, 171-191.
70
Modern IQ Test Design
• Reliability (over time)
–
–
•
Test-retest
Internal consistency (items hang
together)
Validity (what it measures)
–
–
–
Content (face validity)
Criterion (relationship with other knowns)
Construct (ability to differentiate)
71
Want to learn more about intelligence?
A comprehensive exploration of
intelligence theories throughout history
- from Plato to Jensen - is available at:
http://www.indiana.edu/~intell/map.html
72