Intelligence
Definition individual differences in the
ability to acquire knowledge, to think and reason effectively, and to deal adaptively with the environment
(Passer & Smith)
History of Intelligence Testing
Francis Galton (1822-1911) cousin of Charles Darwin advocate of hereditarian position Hereditary Genius
study of eminence creates first “intelligence” tests
Alfred Binet (1857-1911) develops test to identify those who
would benefit from remediation (mental orthopedics)
Mental Age (MA)
a measure of the developmental level on which a person is functioning
a person with a mental age of 8 years can successfully complete the same intellectual tasks as the average 8-year-old child
measure given by the Binet-Simon scale
Age-Related Tasks From Binet’s 1911 Test
Three-Year Old should be able to point to body parts such as eyes,
nose, and mouth repeat sentences of six syllables (e.g.,
The girl ran up the hill) identify common objects in a picture
Age-Related Tasks From Binet’s 1911 Test
Seven-Year Old should be able to understand the difference between
left and right describe a picture count the value of six coins carry out three commands given in a
sequence (e.g., clap hands, hop forward, and touch nose)
Age-Related Tasks From Binet’s 1911 Test
Fifteen-Year Old should be able to find three rhymes for a word in a
minute repeat seven digits interpret a set of facts repeat a 26 syllable sentence(e.g., The young gentleman helped the
old woman carry her belongings up the steep staircase to her room last night)
History of Intelligence Testing
III. Intelligence Tests in America Goddard
1908 translates Simon-Binet test into English
staunch heredetarian Terman
develops Stanford-Binet test in 1916
IQ - Intelligence Quotient
originally derived by German psychologist William Stern (1914)
uses both mental age and chronological ageMA
IQ *100CA
Bobby: CA=5 MA= 2
Ginny: CA=15 MA= 12
MA 2IQ *100 *100=40
CA 5
MA 12IQ *100 *100=80
CA 15
History of Intelligence Testing
Wechsler’s ContributionsWAIS
Wechler Adult Intelligence ScaleWISC
Wechsler Intelligence Scale for Children
(ages 5 - 15)WPPSI
Wechsler Primary & Preschool Scale of Intelligence
(ages 4-6)
IV. Measuring Intelligence in AdultsDavid Wechsler
Wechsler’s Contributions (con’t) adopts multifaceted view
Verbal IntelligencePerformance Intelligence
Wechsler Subtests: Verbal Scale
Wechsler Subtests: Performance Scale
Wechsler’s Contributions (con’t)
devises concept of deviation IQ
Extreme’s of IQ
mental retardation subnormal general mental
ability accompanied by deficiencies in everyday living skills originating prior to age 18
Extreme’s of IQ
giftedness top 2-3% of IQ distribution
typically IQ > 130
Psychometric View of Intelligence
Factor Analysis Primary method used to describe
intelligence structure Correlations among many test scores are
examined with the goal of discovering something about the nature of the factors that affect them
How many different factors are needed to explain the pattern of relationships among these variables?
Factor Analysis Matrix
Paragraph comprehension 0.84 0.10 0.06
Sentence completion 0.86 -0.05 -0.01
Word meaning 0.81 0.04 -0.02
Counting dots 0.08 0.91 0.04
Identifying shapes 0.02 0.82 0.10
Multiplication -0.24 0.87 -0.02
Paper folding 0.05 0.20 0.77
Block patterns -0.03 -0.01 0.65
Series completion 0.02 0.04 0.57
Reading Numerical Visual
Psychometric View of Intelligence
A. Spearman’s “g” “positive manifold” in correlation matrix
of various cognitive tests
uses factor analysis to analyze correlation matrix
test performance composed of two factors:
“g” – general intelligence
“s” – specific ability
Psychometric View of Intelligence
B. Thurstone’s Primary Mental Abilities also uses factor analysis certain tests correlate more highly with each
other
Thurstone’s Primary Mental Abilities
argues for seven different mental abilities verbal comprehension word fluency number spatial relations associative memory perceptual speed inductive reasoning
Psychometric View of IntelligenceC. Crystallized and Fluid Intelligence
Cattell (1963) / Horn (1985)
General Intelligence
Crystallized Intelligence
(use of existing knowledge)
Fluid Intelligence(solving new problems)
Information Processing & Intelligence
Inspection time How long a stimuli has to be viewed
before an accurate judgment can be made
How quickly a person gives their answer is irrelevant, participants are encouraged to take their time
Inspection Time and IQ
Nettlebeck & Lally (1976) First to note the relationship
Nettlebeck (1987) Inspection time accounts for 25% of
IQ variance (r = -.5) The higher the IQ, the less stimulus
time needed to accurately inspect the stimuli
Hereditary & Environmental Determinants of Intelligence
Historical Perspectives Francis Galton/Lewis Terman
hereditarian/nature perspective John Stuart Mill/Binet
environmental/nurture perspective More Recent Views
Phillipe Rushton Arthur Jensen Leo Kamin
Evidence Supporting Hereditarians’ Position
Galton’s Study of Eminence Hereditary Genius
Twin Studies
Evidence Supporting Hereditarians’ Position
Adoption Studies Child/Natural Mother: r=0.22 vs Child/Adoptive Mother: r=0.15
Evidence Supporting Environmentalists’ Position
Adoption Studies child & adoptive mother: r=0.15
siblings reared together: r=0.47 vs
siblings reared apart: r=0.22
fraternal twins: r=0.58 vs
siblings r=0.43 unrelated siblings: r=0.30
Evidence Supporting Environmentalists’ Position
Altered Environments Impoverished Environments
cultural deprivation hypothesis 1920 English canal children children reared in Kentucky mountains
Enriched Environments Home-Environment Studies Flynn-effect
Interactionist View
reaction range heredity sets limits on intelligence
while environmental factors determine where individual falls
Reaction Range
Cultural Differences in IQ
10-15 IQ point difference between average Caucasian and Black Americans
Possible Explanations Jensen’s Heritability Explanation
(1969) hereditability for IQ: H = 0.80
Heritability EstimatesHeritability Ratio: estimate of
proportion of trait variability in a population that is determined by variations in genetic inheritance
G
T
H VV
where:
VG = variance due to genetic differences VT = total trait variance
Cultural Differences in IQ
Possible Explanations Kamin’s Rebuttal of Jensen
Cultural Differences in IQ
Possible Explanations (con’t) Cultural Disadvantage
minority groups live in impoverished environment
Cultural Bias on IQ Tests tests administered by whites tests reflect white, middle-class values tests written in “white” language
Psychometrics
Psychological test standardized measure of a
sample of a person's behavior
Concepts related to Standardization
Norms Percentile Score
Correlation Coefficient
Height Weight 5.8 160 6.0 190 6.2 200 6.1 195 5.9 180
r = 0.95
index that assesses degree of linear relationship between two variables
Reliability
the consistency with the test measures what it measures
Person Time1 Time2 Time3 Fred 5 5 7 Ann 7 7.5 10 Amy 9 8.5 10 Juan 12 12
8
Correlation with
Time 1 Score
r=.99 (high)
r=.17 (low)
Ways of Assessing Reliability
test-retest alternative forms split-half
internal consistency Cronbach’s
Validity
refers to the ability of a test to measure what it was designed to measure
Methods of Assessing Validity
content validity criterion-related validity
predictive validity construct validity
convergent validity discriminant validity
last day for Research Participation is Monday December 1st.
Check your Research Participation grade – maximum 6% – on WebCT after 2:00 pm on Thursday December 4th
If you think there is an error, e-mail [email protected] by noon Friday December 5th.
Psyc 102 Fall 2008 Final Exam
Thursday December 4th 12:00-14:00 100 multiple-choice questions
~50% Chapters 8, 9, & 11 ~50% Chapters 12-16
bring SFU ID, pencil, eraser
If your last initial is between A-Q you’ll write in C9001
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