Intelligence
Intelligence
• Wechsler defined it as the global capacity to think rationally,
act purposefully, and deal effectively with the environment
• The ability to learn from experience, solve problems, and
use knowledge to adapt to a new situation
• Intelligence is reflected in effective, rational, and goaldirected behavior.
• Is intelligence one thing or are there multiple intelligences?
• Play “Pros and Cons of Intelligence Tests” (6:29) Segment
#17 from Psychology: The Human Experience.
– This is a good review of what you’ve read and highlights how IQ
tests have been used in a variety of ways by the government and
other agencies.
Measuring Intelligence
Intelligence tests try to measure general
mental abilities not “book smarts” or
knowledge in a specific area
Intelligence Testing:
Alfred Binet
Binet’s “Mental Age”
• Hired by the French government to develop a test to
determine students who had special needs.
• His test focused on mental abilities like memory, attention,
and the ability to understand similarities and differences
NOT math and reading.
• Arranged questions in order of difficulty with simplest first.
• Compared student’s performance with those of other kids
their age.
• Developed the term, “mental age” which meant the age of
the child’s mental abilities. A seven year old operating at a 9
year old’s level would have a mental age of 9.
• Binet never meant for his test to be used to measure
intelligence. He only wanted to identify kids with special
needs.
• He felt intelligence was too complex to capture in a test.
Alfred Binet
• Intelligence—collection of higherorder mental abilities loosely related to
one another
• Assumed children’s intellectual
abilities grew every year
• Intelligence is nurtured
• Developer of the first test to classify
children’s abilities using the concept of
mental age. Used to predict academic
performance
• Did not rank “normal” students
according to the scores
1859-1911
Intelligence Testing:
Lewis Terman
(1877-1956)
Lewis Terman
•Terman believed that IQ was a fixed, inborn characteristic
and would equate in to school success (this against what
Binet believed).
•Terman did a longitudinal study of children whose
average IQ scores were 150 (140 is genius level).
 Found that intelligence alone is not enough to be a
success.
 Only those that had personality factors that were more
goal-oriented, greater perseverance and self-confidence.
 Essentially, those with a willingness to work hard
were successful. Intelligence is no guarantee of success
in professional life.
Lewis Terman & William Stern
Stanford-Binet IQ Test
•Intelligence Quotient - The number that results
from Terman and Stern’s formula for computing
the level of a person’s intelligence
Stanford-Binet Intelligence Test
IQ=(MA/CA)*100
IQ=Intelligence Quotient
MA=Mental Age
CA=Chronological Age
• A score of 100 would be considered average
• Formula has been replaced with modern versions
Calculating Intelligence
For an average 7 yr old…
MA=7
CA=7
IQ=(MA/CA)*100
IQ=(7/7)*100
IQ=1*100
IQ=100 (average)
Calculating Intelligence
For an average 11 yr old…
MA=11
CA=11
IQ=(MA/CA)*100
IQ=(11/11)*100
IQ=1*100
IQ=100
Calculating Intelligence
For an above average 10 yr old…
MA=12
CA=10
IQ=(MA/CA)*100
IQ=(12/10)*100
IQ=1.2*100
IQ=120
Calculating Intelligence
For a below average 8 yr old…
MA=6
CA=8
IQ=(MA/CA)*100
IQ=(6/8)*100
IQ=.75*100
IQ=75
Calculating Intelligence
A glitch…
MA levels off at about 18
Average 18 yr old
MA=18
CA=18
IQ=(18/18)*100
IQ=(1/1)*100=100
Average 36 yr old
MA=18
CA=36
IQ=(18/36)*100
IQ=(1/2)*100=50
Problems with Intelligence
Testing
• Army Alpha written test and the Army
Beta oral test used in WWI to test the
IQ of recruits and draftees.
• These later used by immigration and
resulted in certain nationalities being
labeled as “unfit” resulting in quotas.
How Much Stock can we put into
IQ Scores?
• Not too much.
• To regard an abstract concept as if it were a
real, concrete thing is called reification.
Modern Intelligence
Tests:
Weschsler Test
Group Tests
David Wechsler (1896-1981)
• Developed the Wechsler
intelligence scales which
included:
– Different tests for different
age groups
– Separate verbal and nonverbal
scores
– Subtests and subtest scores
The Wechsler tests
• Modeled after Binet’s but improved it in two ways.
1. Designed test for both adults and children.
– WISC-IV = Wechsler Intelligence Scale for children
– WAIS-IV = Wechsler Adult Intelligence Scale
2. Provided scores in 11 different subtests for 11 abilities
which were grouped to show a performance and verbal
score.
• It showed an individual’s strengths and weaknesses
in a variety of areas.
The Subtests of the Wechsler Test
and how they’re used
• Verbal score – obtained from subtests in vocab,
comprehension, knowledge and general info.
• Performance score – obtained by nonverbal subtests like
identifying the missing part in a picture, arranging pictures
into a story, arranging blocks to match a pattern.
• Discrepancies in certain scores (high score in one area with
a low score in another area can indicate a learning
disability). It can also mean there was a cultural
disadvantage for the person taking the test.
• IQ Global score determined by comparing to the average
score of others in your same general age group rather than
by mental age. Average score is fixed for each age group at
100. Average or 2/3 of all scores fall between 85-115.
Subtests of Wechsler
Testing Spatial Reasoning
Measures of Intellectual Disability
Test Construction:
Reliability and
Validity
Types of Tests
• Achievement test—designed to measure level of
knowledge, skill, or accomplishment in a
particular area
– classroom tests at the end of a unit
• Aptitude test—designed to measure capability to
benefit from education or training
– ACT and SAT
• Interest test—measures self-reported vocational
interests and skills
– PLAN Test
Qualities of Good Tests
• Standardized—administered to large
groups of people under uniform conditions
to establish norms
• Reliable—ability to produce consistent
results when administered on repeated
occasions under similar conditions
• Valid—ability to measure what the test
is intended to measure
Standardized Scoring
of Wechsler Tests
• All raw scores
converted to
standardized
scores
• Normal
distribution
• Mean of 100
• Standard
deviation of 15
Types of Reliability
• Test-retest reliability - taking the same test
and receiving a similar score
• Split-half - the score on one half of a test’s
questions is similar to the score on the
other half
• Scorer reliability – the score of the test
should be similar no matter which scorer is
scoring the test
What do IQ tests measure
about your mind?
• Mental speed and span of working
memory
– typically use a digit span test to measure this
– more recent studies find significant correlations
between reaction times and IQ scores
• Why is this important?
– mental quickness may expand capacity of
working memory
Test Validity
• The extent to which a test measures or
predicts what it is suppose to
• Does an achievement test accurately
measure accomplishments?
• Does an aptitude test accurately measure
the person’s future performance?
• One needs to know the purpose of the test