EXTREMES OF
INTELLIGENCE
MENTAL RETARDATION
• DEF: subaverage
general mental ability
accompanied by
deficiencies in
adaptive skills,
originating before age
18
• IQ score of 70 or lower
• 1-3% of the population
LEVELS OF RETARDATION
• Characterized as mild,
Super
Swaggy!
moderate, severe, or
profound
• Most fall under mild
• Majority are
unrecognizable outside
of schooling
ORIGINS OF RETARDATION
• Down syndrome
involves and extra
chromosome
• Phenylketonuria is an
inherited enzyme
deficiency
• Hydrocephaly is an
excessive
accumulation of
cerebrospinal fluid in
the skull
GIFTEDNESS
• Identifying giftedness comes from IQ tests
• Upper 2-3% of scores are considered gifted (130)
• Gifted tend to be above avg in height, weight, strength,
emotional adjustment, mental health, and social maturity
(Terman)
• Profoundly gifted (scores of 180+) are often introverted
and socially isolated (Winner)
HEREDITARY AND
ENVIRONMENT AS
DETERMINANTS OF
INTELLIGENCE
TWIN STUDIES IN INTELLIGENCE
• Twins develop in
similar environments
and share genetic
kinship
• Even identical twins
raised in separate
environments show
similar IQs
HERITABILITY ESTIMATES
• Heritability ratio: an
estimate of the
proportion of trait
variability in a
population that is
determined by
variations in genetic
inheritance
EVIDENCE FOR ENVIRONMENTAL
INFLUENCE
• Adopted children show
more similarity in IQ to
their adoptive parents
• Cumulative deprivation
hypothesis: children
who are raised in
substandard
circumstances should
experience a gradual
decline in IQ as they
grow older
GENERATIONAL CHANGES: THE
FLYNN EFFECT
• James Flynn
discovered that IQ
performance has risen
steadily in the
industrialized world
since 1930
• Reduction in
malnutrition, advances
in technology,
improved schools,
etc…
CULTURAL DIFFERENCES IN IQ
SCORES
• Larger minority groups in U.S. have lower avg IQ scores
•
•
•
•
•
than the avg for whites
Some believe it’s hereditary (no proof)
Others point to socioeconomic disadvantages
Stereotype vulnerability is another explanation
Some argue that IQ tests are culturally biased
Evidence shows that cultural bias produces only weak
and inconsistent effects on the IQ scores of minority
examinees
NEW DIRECTIONS IN THE
ASSESSMENT AND STUDY
OF INTELLIGENCE
INCREASING EMPHASIS ON SPECIFIC
ABILITIES
• Factor analysis:
correlations among
many variables are
analyzed to identify
closely related clusters
of variables
• Attempts to identify
hidden factors
influencing others
• Charles Spearman
EMPHASIS ON SPECIFIC ABILITIES
CONTINUED
• L.L. Thurstone
concluded that
intelligence involves
multiple abilities
• 7 distinct factors: word
fluency, verbal
comprehension, spatial
ability, perceptual speed,
numerical ability,
inductive reasoning, and
memory
EMPHASIS CONTINUED
• Raymond Cattell and
John Horn suggest
fluid and crystallized
intelligence should be
the divisions of
intelligence
EXPLORING BIOLOGICAL INDEXES
OF INTELLIGENCE
• Correlation btwn
reaction time and
higher IQ scores
• Correlation btwn
inspection time and
high IQ scores
COGNITIVE PROCESSES IN
INTELLIGENT BEHAVIOR
• Focuses on how people use their intelligence
• Robert Sternberg
• Triarchic theory of human intelligence
• 3 parts:
• Contextual subtheory: intelligence is a culturally defined
concept
• Experiential subtheory: ability to deal with novelty and
ability to learn how to handle familiar tasks automatically
and effortlessly
• Componential subtheory: describes specific types of
mental processes that intelligent thought depends on
EXPANDING THE CONCEPT OF
INTELLIGENCE
• Many today believe IQ
test focus is too narrow
• IQ tests emphasize
verbal and
mathematical skills
• Howard Gardner
suggests there are
numerous autonomous
human intelligences