Download Chapter 14

Cognitive Processes
PSY 334
Chapter 14 – Individual
Differences in Cognition
Gray Matter is Pruned
Ages 5-20
Gogtay et al., 2004
White Matter Increases
Ages 15 to 75
Prefrontal
cortex
Temporal
lobe
Bartzokis et al., 2001
What Changes?
 Gray matter first thickens then thins as
neurons are weeded out and most-used
connections are strengthened.

Development is sensory and motor first,
then back-to-front with frontal areas last.
 White matter increases with myelination
of axons providing interconnections.

This increases until age 50, then declines.
 Both curves are quadratic, not linear.
What Develops
 Two explanations for changes in
children’s thinking:


They think better – more working memory.
They know better – more facts.
 Probably both occur, due to neural
changes:


Increase in synaptic connections.
Myelination increases neural transmission
speed.
Empiricist vs Nativist Debate
 Not exactly a nature-nurture debate but
concerns where knowledge comes from.
 Nativists argue that the most important
knowledge is part of genetically
programmed development.
 Empiricists argue that virtually all
knowledge comes from experience with
the environment.
 Implications for the potential to change.
Increased Mental Capacity
 Case – memory-space proposal.

Growing working memory development is
the key to the developmental sequence.
 Increased speed of neural function leads
to increased working memory.

Due to increased myelination
 Kail – speed of mental rotation becomes
faster with age (8-22 yo).
Increased Knowledge
 Chi – developmental differences may be
knowledge related.


Children do worse than adults on most
memory tasks.
Where children are skilled at chess and
adults are novices, children do better than
adults.
 Novice-expert comparisons can explain
developmental differences.

Children do not elaborate effectively.
Korkel’s Results
Grade
Soccer Experts
Soccer Novices
3
54
32
5
52
33
7
61
42
There was no effect of grade level, only expertise.
Cognition and Aging
 Decreases in IQ performance scores
occur after age 20:

Related to speed of response on tests.
 Older adults do better on jobs.
 Age-related declines in brain function:



Cell loss, shrinkage & atrophy.
Compensatory growth of remaining cells.
Brain-related degenerative disorders such
as Alzheimer’s.
Mean WAIS-R IQ Declines
Salthouse, 1992
Probability of a Philosopher’s
“Best Book” Declines with Age
Lehman, 1953
Ability to Hold Multiple
Premises in Mind Declines
Salthouse, 1992
Decline is NOT Disability
 Note that substantial proportions of older
individuals are able to write “best books”
or do integrative reasoning even at 70.
 Longitudinal and cross-sectional studies
have problems:


Age cohorts have different historical
experiences (Great Depression, nutrition)
Everyone declines from their own unique
baseline, not relative to a group.
Use it or Lose It
 With cognitive exercise:


Number of neurons declines but number of
synapses per neuron increases.
Brain weight increases with age.
 Without cognitive exercise:


Number of neurons and brain weight both
decline.
Number of synapses per neuron declines.
 Learn new things and stay active!
Psychometrics
 Measures of performance of individuals
on a number of tasks – examination of
correlations across such tasks.


IQ Tests – Binet, Stanford-Binet, Wechsler
Mental age vs deviation IQ.
 Factor analysis of performance scores:


Crystallized intelligence – increases with
age
Fluid intelligence – decreases with age.
Distribution of S-B IQ Test
Scores
IQ Score
Traditional Ranking System
140 + (~.25%)
Genius or near genius
130 - 139
Gifted
120 - 129
Very Superior Intelligence
110 - 119
Superior Intelligence
90 - 109
Average/Normal
80 - 89
Dullness
70 - 79
Borderline deficiency
50 - 70
Mild mental retardation
35-50
Moderate mental retardation
20 - 35
Severe mental retardation
< 20
Profound mental retardation (1%)
Kinds of Abilities
 Reasoning ability:


Sternberg connects psychometrics to the
information-processing approach.
People who score high on reasoning tests
perform reasoning steps more quickly.
 Verbal ability:


Working memory capacity is related to
verbal ability.
People who recall words more rapidly do
better on verbal ability tests.
Kinds of Abilities (Cont.)
 Spatial ability:


Rate of mental rotation is slower for those
with lower spatial ability test scores.
People with high spatial ability may choose
to solve a problem spatially, not verbally.
 Differences in abilities may result from
differences in rates of processing and
working-memory capacities.

Unclear whether this is innate or a
difference in practice (nature vs nurture).