Intelligence
Meredyth Daneman
PSY100
What is Intelligence?


abstract reasoning, problem solving, capacity to
acquire knowledge
memory, mental speed, linguistic competence,
mathematical competence, general knowledge,
creativity

sensory acuity, goal-directedness, creativity

what intelligence tests measure
Overview

Nature of intelligence

Methods to measure intelligence

Theoretical approaches

Heredity and intelligence
Nature of Intelligence

Functional

Multi-faceted

Culturally Defined
Nature of Intelligence

Provisionally define intelligence as:
the application of cognitive skills and
knowledge to learn, solve problems,
and obtain ends that are valued by
an individual culture
Intelligence Testing
Intelligence tests are measures
designed to assess an individual’s level
of cognitive capabilities compared to
other people in the population
Intelligence Testing (Galton)
Sir Francis Galton

believed building blocks of intelligence are
simple sensory, perceptual, and motor
abilities

found that these elementary tasks did not
correlate with much of anything

pioneering statistician – correlation
Intelligence Testing (Binet)
Binet


believed that a true measure of intelligence
is an individual’s performance on complex
tasks of memory, reasoning, and
comprehension
developed the concept of “mental age” or
“mental level”
Intelligence Testing
A child’s mental age (MA) indicates that he/she
displays the mental abilities of a child of that
chronological age (CA)

a child with a CA of 5 who can answer questions a
typical 7-yr old answers, has a MA of 7

a 5-yr old who can answer the questions expected
for his/her age but no older, has a MA of 5
Intelligence Testing (Terman)
Terman


revised the scales: Stanford-Binet
intelligence quotient (IQ), a score meant to
quantify intellectual functioning to allow
comparison among individuals
IQ = (MA/CA) X 100
8yr old performs at level of 12yr old


12yr old performs at level of 8yr old


(12/8) X 100 = 150
(8/12) X 100 = 66
12yr old performs at level of 12yr old

(12/12) X 100 = 100
Intelligence Testing (Wechsler)
Wechsler

developed test that could be used for adults


WAIS (adults)
WPPSI (children)

verbal and performance subtests

frequency distribution of IQ scores
Wechsler Intelligence Scales:
Verbal IQ
Wechsler Intelligence Scales: Performance
IQ
Frequency Distribution of IQ Scores


Original IQ formula was useful for assessing
children’s test performance, but not adults’
test performance
Wechsler remedied the problem by
abandoning concept of MA and calculating IQ
as an individual’s position relative to peers of
the same age on a frequency distribution
The scores on an
IQ test form an
approximately
bell-shaped
curve. The curve
shown here
represents
scores on the
Wechsler IQ
test, with a
standard
deviation of 15
(15 points
above and
below the mean,
which is 100).
The Extremes of Intelligence

Mental retardation:




IQ less than 70
about 2% of population
75-90% are in mild to moderate range
(IQ 50-70)
10% in severe to profound range
(IQ below 50)
The Extremes of Intelligence

Giftedness:

IQs exceeding 130
Validity & Reliability of IQ Tests


Validity: the ability to assess the
construct it was designed to measure
Reliability: the ability to produce
consistent results
IQ Testing: Criticism & Controversy

Lack of theoretical basis

Are IQ tests culturally biased?

Are IQ tests valid?
Approaches to Intelligence

psychometric approach

information-processing approach

multi-component approach
Psychometric Approach


The psychometric approach tries to
identify groups of items in a test that
correlate with one another in order to
discover underlying skills or abilities
Factor analysis: a statistical procedure for
finding patterns of correlations among
measures in order to identify underlying
factors or mental abilities
Identifying a Common Factor
Sprint Weights
Pullups
Situps
--------------------------------------------------------------------Sprint
---
.35
.45
.41
Weights ---
---
.70
.52
Pullups
---
---
.37
---
Situps
------------------------------------------------------------------------------
Spearman’s Two-Factor Theory
general factor or g-factor
specific factors or s-factors
Cattell’s Theory

Fluid intelligence


speed and accuracy for abstract reasoning,
especially for novel problems (drawing
inferences, finding analogies, recognizing
patterns)
Crystallized intelligence

accumulated knowledge and vocabulary
Thurstone: seven primary abilities







word fluency
comprehension
numerical computation
spatial skills
associative memory
reasoning
perceptual speed
Information-Processing Approach


tries to understand the processes that underlie
intelligent behaviour; e.g., what is general
intelligence or “g”?
various proposals:



working memory capacity
retrieving information from long-term memory
speed of processing (inspection time)
Theory of Multiple Intelligences (Gardner)

Seven intelligences







musical
bodily/kinesthetic
spatial
linguistic or verbal
logical/mathematical
intrapersonal
interpersonal
Gardner

Savants


one island of brilliance
Prodigies

extraordinary and generally early
developing genius in one area, but normal
abilities in others
Heredity and Intelligence
Evidence for Hereditary Influences

twin studies

adoption studies
Heredity and Intelligence
Evidence for Environmental Influences

adoption studies

environmental deprivation &
enrichment

generational change (the Flynn effect)
Flynn Effect



IQ has been rising steadily over the
industrialized world since 1930s
Has to be attributed to environmental factors
Hypotheses:



reductions in severe malnutrition
advances in technology (TV, computers, video
games)
improved schools, smaller families, better
educated and informed parents
Heredity vs. Environment
individual differences
vs.
group differences
.