PERSONALITY AND INDIVIDUAL DIFFERENCES

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PERSONALITY AND INDIVIDUAL DIFFERENCES

• Overview of Alan Garnhams Lectures on
  Intelligence

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TOPICS

• History of Intelligence Testing
• Lecture 1
• Psychometric Approaches to Intelligence and
  Factor Analysis
• Lecture 2
• Information Processing Approaches to Intelligence
• Theories of Multiple Intelligences
• Lecture 3

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PERSONALITY AND INDIVIDUAL DIFFERENCES
INTELLIGENCE

• Intelligence 1 History of Intelligence Testing

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OVERVIEW

• Sources of Modern Approaches to Intelligence
• Craniometry
• Galton
• Binet and Simon
• The Development of IQ testing in the USA
• Outcome - the 1924 Act
• Later Developments in the US
• Other Tests
• Issues in Test Design

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CRANIOMETRY

• Either measuring cranial capacity (e.g. by
  filling skull with lead shot), or measuring brain
  size (after death)

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CRANIOMETRY cont.

• USA - Early 19thC - Amerindians vs settlers vs
  Blacks (Samuel Morton - theory of polygeny of
  human races)

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CRANIOMETRY cont.

• Europe - Later 19thC - Paul Broca (of Aphasia
  fame)

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CRANIOMETRY - cont

• US work - an early example of finding results to
  fit the theory in intelligence testing
• Europe - huge range of brain sizes in eminent
  persons (e.g. Ivan Turgenev, over 2000gm Anatole
  France just over 1000gm). But Broca also made
  claims about different races.

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Big Brain Small Brain
Ivan Turgenev
Anatole France
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GALTONS WORK -Precursors

• First empirical data showing that human
  characteristics followed a normal distribution -
  Quetelet Belgian 19th C
• This work was on physical characteristics
• Darwin - importance of variation between
  individuals in evolution - if characteristics
  inherited

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GALTON

• Galton (cousin of Charles Darwin) wanted to
• extend the work to nonphysical properties
• investigate the role of heredity

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GALTONS WORK - Cont

• Galton - argued that psychological
  characteristics could be inherited.
• with Spencer used the term intelligence in an
  approximately modern way, and believed in a
  "general ability"

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GALTON - cont

• Focused (in the nonphysical domain) on the
  eminently (!) Victorian characteristic of
  eminence (as indicated by reputation), which he
  believed
• was an indication of intellegence
• ran in families
• Charged people (3d) to be measured and tested in
  various ways at the International Exposition of
  1884

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GALTON - Cont

• Measured characteristics such as perceptual
  sensitivity, but failed to find clear relations
  with eminence

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GALTON - cont.

• Galton and his associates (in particular Karl
  Pearson, left) invented the mathematical methods
  of measuring correlation that have been so
  important in the study of intelligence and
  personality (they form the foundation of factor
  analysis - see later in the course)

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BINET AND SIMON

• Originators of the Intelligence Test as we know
  it
• Although Binet was a well-known theoretician, he
  was chosen to solve a purely practical problem
• To identify children who could benefit (or not)
  from mainstream education (just made
  universally available in France)

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BINET cont.

• Binet had been attracted by Craniometry,but
  suspected (and demonstrated) experimenter bias
• So, adopted a different and purely pragmatic
  approach to his problem

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BINET-SIMON TEST

• Sample items copy drawing, repeat string of
  digits, recognise coins, calculate change,
  explain an absurdity
• may rely on background knowledge of "common
  culture"
• composite score correlated with school grades and
  teacher's evaluation of intelligence.

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BINET-SIMON TESTS

• Standardised on kids of different ages, so a kid
  can be assigned a mental age.
• Binet originally focused on MA - CA as a measure
  of (relative) ability
• Stern 1912 proposed IQ(MA/CA) x 100 - ratio more
  appropriate
• Note however, that CA/MA measures only make sense
  for kids

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STERN INVENTED IQ
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BINETS TEST IN THE USA

• Goddard took the Binet scale to America
• Unlike Binet suggested the idea of single innate
  thing that the scale measured

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BINETS TEST IN THE USA

• Lewis Terman - hereditarian position, at
  Stanford, standardised the Binet for USA
  (Stanford-Binet, 1916)

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TESTING GOES LARGE

• Yerkes - US WW1 soldiers. 1.75 million tested,
  using tests based on Stanford-Binet. Also adopted
  a hereditarian position

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TESTING GOES LARGE

• Army Alpha and Army Beta - group tests (as are
  modern SAT and GRE Scholastic Aptitude, Graduate
  Record)
• Beta mainly nonverbal - for people who didn't
  speak English very well

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RESULTS FROM ARMY TESTS

• Average MA for white males 13
• European immigrants worse (north better than
  south - Russians 11.34 Poles10.74)
• Blacks 10.41
• However, the army test data showed a clear
  correlation between time in school and
  performance

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ARMY TESTS - POLITICAL OUTCOME

• Results were used to influence social policy
  (immigration to US - 1924 act imposed quotas on
  groups from Southern and Eastern Europe -
  including Jews who, therefore, failed to escape
  the holocaust).
• Terman, Yerkes, Boring, Brigham - all favoured
  eugenics (a term coined by Galton)

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LATER DEVELOPMENTS

• 1937 - Terman-Merrill revision of Stanford-Binet
• 1939 - Wechsler adult IQ (test score)/(average
  for norm group) X 100
• notion of deviation IQ - though a centile score
  suggested as more informative (15 IQ points 1
  standard deviation)
  
  

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STRUCTURE OF THE WECHSLER TESTS

• Stanford-Binet had not been standardised on
  adults. Wechsler thought it was too heavily
  loaded on verbal items
• Wechsler tests 11 subscales,
• 6 "verbal" (vocabulary, general comprehension,
  general knowledge, mental arithmetic,
  similarities between pairs, digit span),
• 5 "nonverbal (block design, picture arrangement,
  picture completion, object assembly, digit symbol)

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HISTORY OF THE WECHSLER TESTS

• WAIS - 1944, WAIS-R 1981 (16 -74 yrs)
• WISC - 1949 (5 -15 yrs), WISC-R 1974
• WPPSI (Pre-School Primary Scale of Intelligence)
  1963 (4 - 6.5 years)

David Wechsler
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OTHER TESTS

• Britain - Alice Heim tests, BAS (British Ability
  Scales) 1979 - 24 sub-scales 2.5 -17 years
• Culture-free and/or culture-fair tests(Frijda
  Jahoda, 1966)
• Considerations
• specific cultural factors relating to test items
• general issues, such as familiarity with test
  situations
• A test - Raven's progressive matrices

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ISSUES IN TEST DESIGN

• (aptitude vs ability tests)
• reliability
• validity
• discrimination
• standarisation

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RELIABILITY

• Types of reliability
• test-retest
• alternative forms
• split half
• Aim looking for reliability coefficients of .9
  or more

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VALIDITY

• Types of Validity
• face
• concurrent - with another measure (e.g another IQ
  test!!)
• predictive
• construct
• validity of .6 is good - reduces if range of
  scores restricted (e.g. performance in US high
  school better predicted than college)

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DISCRIMINATION

• wide range of scores is needed
• important for correlation as well
• (see also comment on previous slide)

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STANDARDISATION

• IQ tests need to be standardised if their results
  are to be interpretable
• important to consider relation between
  standardisation group and test group

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USEFULNESS OF TESTS

• If tests are developed for practical purposes
  their success can often be readily assessed
  (aptitude vs ability)
• Selection - fighter pilots (24 failure before
  test, reduces to 10) nb NOT intelligence tests,
  but special tests
• intelligence tests - not so easy to see objective
  property they are measuring (cf. length)