Cognitive Processes PSY 334

1. Cognitive ProcessesPSY 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 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

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).