Assessing Intelligence
Unit 5: Cognitive Psychology
Learning Targets
5.O Identify the contributions of key researchers in intelligence research and
testing.
5.O.1 Contributions of Alfred Binet, key researcher in intelligence
5.O.2 Contributions of Francis Galton, key researcher in intelligence
5.O.6 Contributions of Lewis Terman, key researcher in intelligence
5.O.7 Contributions of David Wechsler, key researcher in intelligence
5.P Explain how psychologists design tests, including standardization strategies
and other techniques to establish reliability and validity.
5.Q Interpret the meaning of scores in terms of the normal curve.
5.R Describe relevant labels related to intelligence testing.
5.R.1 Gifted
5.R.2 Intellectual disability
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Assessing Intelligence
Psychologists define intelligence testing
as a method for assessing an individual’s
mental aptitudes and comparing them
with others using numerical scores.
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Alfred Binet
… and his colleague
Théodore Simon developed
the first standardized
intelligence test…they were
commissioned by the
French government to
design a “test” to identify
French children who would
have problems in regular
classes
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Binet’s impact
Set out to find a child’s mental age, or the average
age of individuals who achieve a particular level
of performance
Binet did not create the test to LABEL children…he
actually warned that if the information were
misused it would do just this…instead he
wanted only to find a way to help improve the
educational experience of French children
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Lewis Terman
(in the US) Terman
adapted/revised Binet’s
test for American school
children and named the
test the Stanford-Binet IQ
Test. (he worked at
Stanford)
▧
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A form of the StanfordBinet is still in use today…
The Stanford-Binet Test
Today…the Stanford-Binet is given orally and varies in
nature according to the person taking the test
▧
Children – given figures to copy or everyday problems
to solve
▧
Adults – asked to solve analogies, explain proverbs and
describe similarities that underlie sets of words
▧
The examiner begins by finding a mental age at which
the person can answer all questions…move on to more
difficult problems…when mental age is reached at which
no items can be answered, test is over
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William Stern
IQ = chronological age = 100
Mental age
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▧ Introduced the
formula of
Intelligence Quotient
(IQ)
▧ IQ is no longer
computed this way…
David Wechsler
… developed the Wechsler
Adult Intelligence Scale
(WAIS) and later the
Wechsler Intelligence Scale
for Children (WISC), an
intelligence test for
preschoolers – they are the
most widely used IQ tests
today.
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WAIS
WAIS measures overall intelligence – consists of 2
parts, verbal and performance
▧
▧
Verbal – vocab definitions and comprehension
Performance – timed assembly of small objects and
arranged pictures in logical order
Normally verbal and performance are within close
range, yet separate scores can give a more precise
picture of a person’s specific abilities
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Types of Tests
Achievement Tests
Aptitude Tests
are intended to reflect
what you have already
learned – current level of
knowledge
are intended to predict
your ability to learn a new
skill – how well you could
do
▧
Examples??
▧
Examples???
▧
AP Psych Exam
▧
ACT/SAT
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Principles of Test Construction
For a psychological test to be acceptable it
must fulfill three criteria:
1. Standardization
2. Reliability
3. Validity
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Standardization
Test items piloted on a similar population of
people and “norms” have been established
▧ Norms are developed by calculating the average
score achieved by a particular group and then
each person’s score can be compared to see how it
differs from people who have taken the test in the
past.
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For example…
The AP Psychology exam you’ll take in May was given to
a sample of freshmen in college within the last few years
to “normalize” the test (to find the norms).
▧ This group that’s given the test to find the norms is
called the standardization sample
▧ The average (one of the norms) from this group is
what this year’s scores will be compared to
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Standardization
periodically tests are re-standardized – given to a
random, representative sample to reset/check the
established norms (including intelligence tests
whose “normal” score is 100).
15
Something to ponder….
Let’s say I took the AP Psychology Exam back in 2005
and got a 4.
▧ Let’s say you get a 4 on this year’s test. What does
the Flynn effect say about the difference in our
scores?
▧ So then why are our scores both a 4?
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Normal Curve
Standardized tests establish a normal distribution of scores on
a tested population — a bell-shaped pattern called the
normal curve.
Numbers to
remember…
Disability
Standard
Deviation = 15
70
100
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130
Gifted
Francis Galton
… argued that intelligence
is quantifiable and normally
distributed, believing we
could assign a score for
intelligence, which then
determined who fell below
the average range and who
fell above it.
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Reliability
A test is reliable when it yields consistent results.
To establish reliability researchers establish different
procedures:
You know
a tape measure
is reliable because every
• Split-half Reliability:
the test
into two equal halves
timeDividing
you measure
your
and assessing how
consistent
theyou
scores
height,
it shows
as are.
• Reliability using different
tests:
Using different forms of
the same
height.
the test to measure consistency between them.
• Test-Retest Reliability: Using the same test on two
occasions to measure consistency.
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Validity
Reliability of a test does not insure validity.
Validity
of a test
refers to
the grader
test is supposed
A testing
example
– Awhat
second
is taking to
When youor
want
to
predict.
a math test.measure
All the problems
are word
measure your weight you
problems with higher vocabulary and he
don’t
use a the
rulerextent
(because
• Content
Validity:
Refers
test measures
a
struggles
to
show to
that he
reallyaknows
math
thattrait.
would not be a
particular
behavior
because
of it. or
Is that test measuring ONLY his
VALID
assessment
of of a test in
• Predictive
Validity:
Refers
tovalid
the function
math?
No, it’s
not a
measurement
of
your
weight).
predicting
a particular
or trait.
math
skills duebehavior
to high-level
vocabulary.
A test can be reliable but not valid. Meaning it yields
consistent results, but doesn’t measure what it says it’s
measuring.
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Extremes of Intelligence
Unit 5: Cognitive Psychology
Extremes of Intelligence
A valid intelligence test divides two groups of people into two
extremes. The intellectually disabled (IQ 70) and the
intellectually gifted (IQ 130) are significantly different.
Numbers to
remember…
Disability
Standard
Deviation = 15
70
100
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130
Gifted
Intellectual Disability
Having significantly below-average intellectual
functioning and limitations in at least two areas of
adaptive functioning
▧
▧
▧
▧
▧
communication skills
self-care
ability to live independently
social skills
community involvement
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▧
▧
▧
▧
self direction
health and safety
academics
leisure and work
Intellectual Disability
Causes can be varying factors, but can include
▧ Genetics (down syndrome)
▧ Environmental (FAS, SBS)
▧ Deprivation/neglect
▧ No apparent/known cause
There is no cure, but some preventative measures can
be take for certain causes of intellectual disability…
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Intellectual Disability
▧ test performed on newborns tests for hidden
genetic disorder called PKU…if detected early,
the intellectual disability associated with PKU
can be prevented by a special diet
▧ more generally…genetic counseling, pregnancy
care services and education of new parents are
other preventative strategies
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Intellectual Disability Levels
Mild (50-70 IQ)
85% of all MR –
academic
abilities at
approx. 6th
grade level…can
learn to live on
own and hold a
job
Moderate (3549 IQ)
Severe (20-34
IQ)
Profound (below
20 IQ)
academic
abilities approx.
2nd grade level –
can be trained
in self-care and
acquire some
reading/writing
skills, yet need
some
supervision
mental capacity
of approx. a 5year-old – learn
to talk in most
cases and
perform simple
tasks, yet need
close
supervision
mental age less
than 3 – very
limited
communication
and require
constant
supervision…
numerous
physical
disabilities
common.
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Intellectual Gifted
… have IQ scores above 130-135.
Most extensive research on “giftedness” was done by
Terman...resulting data much of what we know about
subject
▧
▧
studied 1528 students near top of IQ range into adulthood
found that gifted children excelled in school, had overall
good health, were generally happy (newer research
suggests that highly gifted children may be susceptible to
certain physical or psychological disorders)
▧
most continued on a path of success, yet most led
ordinary, undistinguished lives
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