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 galder@sfu.ca 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

If your last initial is between R-Z you’ll write in C9002