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Intelligence Testing

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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

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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

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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

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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.

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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 experienceii) 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!

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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

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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

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Prehistoric Time

• abandonment• murdered• failure to survive (hard life style)

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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

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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.

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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.

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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

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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

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Era of Asylum

• Lasted approximately 100 years• Concept of equality and the

concept of humanism arose

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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)

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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

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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)

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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

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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

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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

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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)

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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)

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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

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Psychological Measurement in the 20th

Century• Public education and availability

of limited funds• Needs of the military for allocating

personnel (WW I)

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The History of IQ testingThe 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

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The History of IQ testingThe 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

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The history of IQ testingThe 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

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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).

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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

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Henry Herbert Goddard

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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

Stanford-Binet Intelligence Scale

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Lewis Terman (1916-72)

– Developed Intelligence QuotientIQ = (MA/CA)*100

MA= Mental Age; CA = Chronological Age

1916 Stanford-BinetSample Items for 12 yr olds

1. Orange. 45. Sportive. 80.

Exaltation.

92. Theosophy

• FOR THE STARTED AN WE COUNTRY EARLY AT HOUR

• TO ASKED PAPER MY TEACHER CORRECT I MY

• A DEFENDS DOG GOOD HIS BRAVELY MASTER

3-1-8-7-9

6-9-4-8-2

5-2-9-6-1

VocabularyGrammar

Memory• Snake, cow, sparrow

• Book, teacher, newspaper

• Wool, cotton, leather

Similarities

Interpretation

Practical Problem Solving

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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)

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IQ testing in the USAIQ 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

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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

Army Alpha Results by Years of Education

Army Alpha Results by Years of Education

Army Beta Results by Years of Education

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S J Gould - A Nation of MoronsS 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

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S J Gould - A Nation of MoronsS 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

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S J Gould - A Nation of MoronsS 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

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S J Gould - A Nation of MoronsS 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

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Test conclusionsTest 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

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S J Gould - A Nation of MoronsS 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”

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S J Gould - A Nation of MoronsS 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

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S J Gould - A Nation of MoronsS 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

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S J Gould - A Nation of MoronsS 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

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S J Gould - A Nation of MoronsS 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

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S J Gould - A Nation of MoronsS J Gould - A Nation of Morons

•Gould estimates that

•Immigration quotas barred up to 6 million people from entering the USA

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S J Gould - A Nation of MoronsS J Gould - A Nation of Morons

•There is still no good evidence to suggest that IQ differences are the result of genetic differences

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S J Gould - A Nation of MoronsS 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

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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)

WAIS-R Testing kit

Testing Booklet

Story Cards

Puzzle Pieces

Block Design

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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

Matrices Example Item

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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

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

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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

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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

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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)

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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

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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

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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)

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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…]

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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.

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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)

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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