Why you is so smart
Origins of Intelligence
Testing

 Alfred Binet & Theophile Simon create aptitude test
to better organize classrooms
 Philanthropic roots
 Problems?
Binet and Simon’s Test

 Measured aptitude instead of achievement
 Aptitude: potential & natural ability (“natural
intelligence”)
 Achievement: accumulated knowledge
 Mental Age: average test score of children in
different age groups
IQ Version 1.0

 Intelligence Quotient AKA “Ratio IQ” a statistic
obtained by dividing a person’s mental age by the
person’s physical age and then multiplying by 100
 For example: (Mental Age of 10/Physical Age of 10) x
100 = 100
 Problems?
IQ Version 2.0

 Deviation IQ: a statistic obtained by dividing a
person’s test score by the average test score of people
in the same age group and then multiplying the
quotient by 100
 Does not allow comparisons between people of
different ages
Wechsler Adult Intelligence Scale
(Deviation IQ)

What do intelligence
tests really measure?

 Remember, “intelligence” is an abstract concept, not
a THING that can be measured like a thermometer
measures air temperature
 OPERATIONAL DEFINITION!
 WAIS uses 13 subtests to measure things like
vocabulary, the ability to notice similarity and
differences, drawing inferences, etc.
 Why were these 13 groups chosen?
Are they really useful?

 If intelligence tests don’t actually measure
INTELLIGENCE, can they really tell us anything
useful?
 Validity: does the test measure what it’s supposed to
measure?
 Concurrent Validity: does the test provide accurate
information about the state of things NOW?
 Predictive Validity: does the test allow you to PREDICT
what will happen LATER?
 Construct Validity: does the test demonstrate an
association between test scores and a theoretical trait?
Reliability

 Reliability: does the test yield consistent results as
it’s repeated?
 Equivalent-Form Reliability: correlation between
different forms of a test
 Test-Retest Reliability: correlation between a person’s
score from test to test
 Tests with reliability but no validity?
 Tests with validity but no reliability?
So, what good are
intelligence tests?

 Intelligence test scores are best predictor of: number
of years of education you will receive; future income;
likelihood of committing crimes; how well
employees will perform in their jobs
 Those who rank high in intelligence tests also tend to
take less time discriminating between different stimuli
HOWEVER!

 Although moderately gifted children (those with
IQ’s of 130-150) are generally as well adjusted as
their less intelligent peers, profoundly gifted
children (with IQ’s of 180 or higher) have a rate of
social and emotional problems that is twice that of an
average child!
 Profoundly gifted no more likely than moderately
gifted children to become major contributors to the
fields in which they work
Intelligence: Just One
Thing?

 Charles Spearman’s Two Factor Theory of
Intelligence: every task requires a combination of a
general ability (“g”) and skills that are specific to the
task (“s”)
 Factor Analysis: a statistical technique that explains a
large number of correlations in terms of a small
number of underlying factors
 Spearman: “Most measures of intelligence are
correlated…therefore, G EXISTS!”
…Or Three Things?

 Sternberg’s Triarchic Theory: intelligence is
composed of
 Componential or Analytic Intelligence
 Traditional “intelligence” tests, comparing and
contrasting, explaining, analyzing
 Experiential or Creative Intelligence
 Using knowledge in NEW ways
 Contextual or Practical Intelligence
 “Street smarts”: applying knowledge to real-world
situations
Intelligence: A Bunch of
Things?

 Louis Thurstone’s Primary Mental Abilities:
“Intelligence” is really a number of smaller
subgroups of ability. These include word fluency,
verbal comprehension, memory, and perceptual
speed.
 Thurstone noticed that proficiency at some activities
are highly correlated while others aren’t
Turns Out…It’s BOTH!

More On John Carroll’s
Types of Intelligence

 Determined by a “bottom-up” approach: measuring
correlations between proficiencies at various related
activities
 Fluid Intelligence: the ability to process information
 Crystalized Intelligence: the accuracy and amount of
information available for processing
 Alzheimer’s disease impairs fluid intelligence more
strongly than crystallized intelligence
Howard Gardner’s
Intelligences

 Linguistic, logical-mathematical, spatial, musical,
bodily-kinesthetic, interpersonal, intrapersonal, and
naturalistic
 Measures of intelligence are culturally relative
 Some African societies associate intelligence with
silence and deliberate speech whereas Americans tend
to associate intelligence with quick, frequent speech
Gardner’s Multiple
Intelligences

Intelligence: Nature or
Nurture?

 Heritability Coefficient: a statistic that describes the
proportion of the difference between people’s
intelligent score that can be explained by genetics
 Heritability of intelligence in large samples tends to
be .5
 Does this mean half of your intelligence determined by
genetics and half determined by experience?
Heritability Coefficient
Explained

Nature vs. Nurture

Intragroup Differences

 There ARE consistent differences between
intelligence scores of different races
 Why?
 Flynn Effect: tendency for intelligence scores to
increase generation-by-generation