How do we Assess Intelligence?
• Alfred Binet and
Theodore Simon set
out to figure out a
concept called a mental
age (what a person of a
particular age should
know).
• They discovered that
by discovering
someone’s mental age
they can predict future
performance.
• Hoped they could use
test to help children,
not label “intelligence”
Terman and his IQ Test
• Used Binet’s
research to
construct the
modern day IQ test
called the StanfordBinet Test.
• IQ=Mental
age/Chronological
age X 100.
• A 8 year old has a
mental age of 10,
what is her IQ?
• A 12 year old has
the mental age of 9,
what is his IQ?
• A boy has the mental
age of 10 and an IQ
of 200, how old is
he?
Problems with the IQ Formula
• It does not really work well on adults, why?
If a 60 year old man
does as well as an average 35 year old
then his IQ would be 50!!!!!!
That makes no sense!!!!!
Wechsler Tests
• More common way to
give IQ tests….does
not use the formula
but uses the same
scoring system.
• WAIS
• WISC
• WPPSI
How do we construct an Intelligence
Test?
• Standardized: the
questions have been
piloted on similar
populations and the
scores fall on a normal
distribution.
• Reliable: The extent
which a test yields
consistent results over
time. Test-Retest,
Split-halves Methods.
• Validity: The extent to
which a test measures
what it is supposed to
measure. Content or
Predictive.
Normal Distribution
In a normal distribution, the mean,
median, and mode are all the same!!
Reliability
A test is reliable when it yields consistent results. To
establish reliability researchers establish different
procedures:
1.
2.
3.
Split-half Reliability: Dividing the test into two
equal halves and assessing how consistent the
scores are.
Reliability using different tests: Using different
forms of the test to measure consistency between
them.
Test-Retest Reliability: Using the same test on two
occasions to measure consistency.
Validity
Reliability of a test does not ensure validity. Validity
of a test refers to what the test is supposed to
measure or predict.
1.
2.
Content Validity: Refers to the extent a test measures your
definition of the construct
Predictive Validity: Refers to the function of a test in predicting a
particular behavior or trait. For instance, we might theorize that a
measure of math ability should be able to predict how well a person will
do in an engineering-based profession.
Extremes of Intelligence
• Akrit Jaswal
Extremes of Intelligence
A valid intelligence test divides two groups of
people into two extremes: the mentally retarded (IQ
70) and individuals with high intelligence (IQ 135).
These two groups are significantly different.
Mental Retardation
• APA “significantly sub-average general
intellectual functioning . . . that is
accompanied by significant limitations in
adaptive functioning.”
• Must appear before the individual is 21 years
old.
• Implies an inability to perform at least some
of the ordinary tasks
Causes
• Not much is known for reasons behind mild
retardation (90% of all diagnosed)
• PKU (phenylketonuria) – liver fails to produce an
enzyme necessary for early brain development
• Down Syndrome – is a genetic disorder caused by the
presence of all or part of an extra 21st chromosome.
• Fragile X syndrome – boys harder hit due to only one
X chromosone
Giftedness
• Terman – (1925)“academic talent and
measured by an IQ in the top two percent of
the population.”
• Renzulli – (1978) above average general
ability, exceptional creativity, and high levels
of commitment
• Motivation added in the 90s
Discussion Questions
• Should public schools practice inclusion?
• Should public funds be used for gifted classes?
• Is singling out certain students as gifted
elitist?
• Are AP classes for gifted students?
Flynn Effect
In the past 60 years, intelligence scores have risen
steadily by an average of 27 points. This
phenomenon is known as the Flynn effect.
Does Intelligence Change Over
Time?
By age 3, a child’s
IQ can predict
adolescent IQ
scores.
Depends on the type
of intelligence,
crystallized or fluid.
Early Theories of Intelligence
• R. B. Cattell
– Identified two clusters of mental abilities
• Crystallized intelligence includes abilities such as
reasoning and verbal skills
• Fluid intelligence includes skills such as spatial and
visual imagery, rote memory, and the ability to notice
visual details
– While education can increase crystallized
intelligence, it was not thought to have any effect
on fluid intelligence
Stability or Change?
Intelligence scores become stable after about seven
years of age. In numerous studies, stability of
intelligence scores have been determined (Angoff,
1988; Deary et al., 2004).