1. Cognitive Processes PSY 334 Chapter 14 – Individual Differences in Cognition

2. Gray Matter is Pruned Ages 5-20 Gogtay et al., 2004

3. White Matter Increases Ages 15 to 75 Prefrontal cortex Temporal lobe Bartzokis et al., 2001

4. 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.

5. 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.

6. 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.

7. 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).

8. 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.

9. Korkel’s Results GradeSoccer ExpertsSoccer Novices 35432 55233 76142 There was no effect of grade level, only expertise.

10. 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.

11. Mean WAIS-R IQ Declines Salthouse, 1992

12. Probability of a Philosopher’s “Best Book” Declines with Age Lehman, 1953

13. Ability to Hold Multiple Premises in Mind Declines Salthouse, 1992

14. 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.

15. 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!

16. 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.

17. Distribution of S-B IQ Test Scores IQ ScoreTraditional Ranking System 140 + (~.25%)Genius or near genius 130 - 139Gifted 120 - 129Very Superior Intelligence 110 - 119Superior Intelligence 90 - 109Average/Normal 80 - 89Dullness 70 - 79Borderline deficiency 50 - 70Mild mental retardation 35-50Moderate mental retardation 20 - 35Severe mental retardation < 20Profound mental retardation (1%)

18. 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.

19. 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).