Intelligence

Introductory Psychology

Topic: Intelligence

A. What is Intelligence?

Autistic savants- Are they intelligent?

individuals who suffer from autism
below average IQ
but have an amazing ability - typically in art, music, memory, or calculating

What is Intelligence?

getting an A on a calculus exam?
writing a great symphony?
discovering a cure for a disease?
easy to recognize, hard to define

"Intelligence, operationally defined, is the aggregate or global capacity of the individual to act purposefully, to think rationally, and to deal effectively with his environment."

David Weschler

B. History of Intelligence Tests

first intelligence tests date back to China ( 2200 BC )
first subject of scientific study - Sir Francis Galton’s Anthropometric Laboratory at the 1884 International Health Exhibition in London
Sir Francis Galton

Measured head size, reaction time, & sensory acuity of 9000 + visitors
influenced by cousin Charles Darwin
better physical (sensory/motor) = more intelligent
intelligence = biological capacity
"Social hindrances cannot impede men of high ability from being eminent .. [and] social advantages are incompetent to give that status to a man of moderate ability."
Looked for correlation between various measures
results disappointing

Binet-Simon Test (1905)

1881 French law
identify students who required special classes
worked with Theodore Simon (psychiatrist) to develop the test
Binet’s ideas regarding intelligence opposite to that of Galton

collection of higher-order mental abilities loosely related to one another
is nurtured through environment

questions related to language, reasoning, arithmetic to children
kept questions which differentiated the age groups
developed concept of mental age
Mental Age : chronological age that most typically corresponds to a given level of performance

child who does as well as the average 8-year-old is said to have a mental age of 8

But mental age sometimes misleading

10 year old with MA = 8; 6 year old with MA = 4

Intelligence Quotient (IQ)

German psychologist W. Stern suggested the ratio of mental age (ma) to chronological age (ca) multiplied by 100
IQ = ma/ca x 100
ma = 8, ca = 10, IQ = 80
ma = 4, ca = 6, IQ = 67

Stanford-Binet Test (1916)

Lewis Terman - psychologist at Stanford - created revised version suitable for American children
also made version for adults
revised 1937, 1960, 1972, 1986
still used today

Weschler Scales

Verbal and non-verbal scales (1939)
Weschler Intelligence Scale for Children (WISC) ages 6 to 16
W. Adult Intelligence Scale (WAIS)
Weschler Preschool and Primary Scale of Intelligence (WPPSI) 4 to 6.5

Sample Items from the WAIS

Weschler Scales

a method of assessing an individual’s mental aptitudes and comparing them to those of others, using numerical scores
with Weschler versions, taker receives a verbal IQ, performance IQ, and an overall IQ score

ratio IQ not suitable for adults

mental age does not increase much for adults
e.g., 15 yr old with MA = 20, thus IQ = 133 (gifted)
later at age 40, MA = 20, IQ = 50

Weschler replaced ratio IQ with standardized IQ

compares person’s IQ test score with the mean score of age peers
if exactly the same as average of peers then IQ = 100
normal distribution (mean = 100, stand dev = 15)

68% of population between 85 and 115
95% of population between 70 and 130

Summary:

The first intelligence tests: how did each figure define & measure intelligence?
Modern intelligence testing: Stanford-Binet vs. Wechsler tests
standardized scoring -- what is “average?”

C. Issues in Intelligence Testing (we won't cover this in class...)

Standardization

Refers both to the establishment of performance norms and to the uniformity in how the test is administered and scored

Reliability- the extent to which a test yields consistent results

assessed by consistency of scores on:

two halves of the test
alternate forms of the test
re-testing the same individual

Stanford-Binet and Weschler scales both have test-retest corrletions of at least .9

I.e., are deemed very reliable

Validity - Does test measure what it’s intended to measure?

Does test correlate with other measures of same construct?
School achievement

IQ tests (I.e., S-B and the Wechsler) correlate highly with academic acheivement, especially in elementary school
On-the-job performance & other work-related variables? The results are not quite so clear cut

Biases (may or may be covered by group presentation)

American blacks score on average 10-15 points lower
1979 California banned use of IQ scores to place black children in classes because greater prop of black children were placed in classes for mentally handicapped
But arguments that IQ tests are NOT biased because they have good predictive validity -- same legal argument presented roughly at same time in Chicago -- this time use of IQ scores said to be appropriate for class placement
obviously, its become a political issue

"perpetuating discrimination" verus "killing the messenger"

Compromise - use tests that are not affected by cultural background (e.g., Raven's Progressive Matrices test)

emphasize perceptual and spatial ability
avoid items which presume an extensive background of particular culture

"in light of the effectiveness of current IQ tests to predict school performance, it is ironic that tests have been outlawed for the very purpose for which they were designed -- to prevent subjective judgement and prejudice from being the basis for assigning students to special classes or denying them certain privileges" (Weinberg, 1989)
The IQ test was invented to predict academic performance, nothing else. If we wanted something that would predict life success, we’d have to invent another test completely." Social psychologist Robert Zajonc (1984)

D. Theories of Intelligence

What is intelligence?
What do the "Experts" Say?

all- abstract reasoning, problem solve, capacity to acquire knowledge
half - memory, creativity, adaptation to envir, mental speed, general know
one fourth - sensory acuity, goal directedness, achievement motivation

Is intelligence a general characteristic that affects all facets of behavior or are there different kinds of intelligence, each affecting a specific facet of behavior?
Galton - a single entity (mental speed)
Binet - a collect’n of different abilities, but yet one IQ score
But can you really summarize intelligence with a single number?

Factor Analytic Theories

Galton - look for correlations among scores of different tests

intelligence defined as a single underlying mental capacity
results were discouraging because of crude measurements and analysis techniques

Charles Spearman (1863-1945)

better tests - memory, visual perception, logic, verbal fluency
factor analysis - determines the degree of correlation between performances on various tasks
All tests correlated with one another
g - "general intelligence factor"
But not perfect correlations, performance on each test depended to lesser extent on specific factors
s - "specific intelligence factor"

Raymond Cattell (1905 - )

student of Spearman’s
modified Spearman’s intelligence theory
thought that general intelligence was not one factor but two
Cattell’s Fluid intelligence - ability to perceive relationships without previous specific experience

matrices tests or verbal analogies

Cattell’s Crystallized intelligence- mental ability derived from previous experience

word meanings
use of tools
cultural practices

Change over years due to decline in fluid knowledge

Problems

depends on tests initially used
assume that intelligence reflects primarily those abilities to do well in school

The Triarchic Approach

Robert Sternberg

asked "joe-average" what is intelligence?

good verbal skills
good problem-solving skills
good social judgement

Componential Intelligence - cognitive - academic performance
Experiential Intelligence - experiences - automatic/creativity
Contextual Intelligence - culture - street smarts

Gardner’s Multiple Intelligences

logical mathematical
linguistic
musical
spatial
bodily-kinesthetic
interpersonal
intrapersonal