3. 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
4. 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
5. 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
6. 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
7. 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!
8. 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
9. 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
11. 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
12. Aristotle stated that man differs 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.
13. 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.
14. 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
15. 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
16. Era of Asylum
• lasted approximately 100 years
• concept of equality and the concept of
humanism arose
17. 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)
18. 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
19. 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)
20. 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
21. 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
22. 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
23. 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)
24. Psychological Measurement in
the 19th 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)
25. 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
26. Psychological Measurement in
the 20th Century
• Public education and availability of limited
funds
• Needs of the military for allocating
personnel (WW I)
27. 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
28. 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
29. 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
30. 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"
(Goddard, 1920, p. 1).
31. 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
33. 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 with care
34. Lewis Terman (1916-72)
– Developed Intelligence Quotient
IQ = (MA/CA)*100
MA= Mental Age; CA = Chronological Age
35. 1916 Stanford-Binet
Sample Items for 12 yr olds
Practical
Vocabulary Problem Solving Grammar
1. Orange.
• FOR THE STARTED AN
45. Sportive. WE COUNTRY EARLY AT
80. Exaltation. HOUR
92. Theosophy • TO ASKED PAPER MY
TEACHER CORRECT I MY
• A DEFENDS DOG GOOD
Interpretation
HIS BRAVELY MASTER
Similarities
• Snake, cow, sparrow Memory
3-1-8-7-9
• Book, teacher, newspaper
6-9-4-8-2
• Wool, cotton, leather
5-2-9-6-1
36. 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)
37. 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)
38. 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; Practical
Judgment; Analogies; Disarranged Sentences; Number Series;
Information
• Beta subtests: Memory; Matching; Picture Completion;
Geometric Construction
42. 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
43. 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
44. 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
45. 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
46. 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
47. 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”
48. 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
49. 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
50. 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
51. 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
52. 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)
53. S J Gould - A Nation of Morons
• Gould estimates that
• Immigration quotas barred up
to 6 million people from
entering the USA
54. S J Gould - A Nation of Morons
• There is still no good evidence
to suggest that IQ differences
are the result of genetic
differences
55. 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)
56. 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)
59. 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
62. 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
63. Support for Support for
Genetic Argument Environmental Argument
Black kids given IQ tests Black kids adopted by middle-class,
in “black English dialect” college educated White families had
still scored 10-15 pts lower higher average scores than general
than general White sample Black sample
Black kids matched to Black kids matched to White kids
White kids on SES and on SES and family variables scored
family variables still much higher on IQ test than general
scored lower on IQ test 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
64. 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
65. 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
66. 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)
67. 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"
• Marilyn Von Savant and her mistakes
68. 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 their adoptive parents
69. 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 out-perform their
pre-adoptive peers (Scarr & Weinberg, 1983)
70. 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, I note that this does not seem to have stopped
humankind from engaging on a huge scale this century
in some dangerously stupid behaviors…]
71. 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.
72. 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)
73. 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
