Cognitive Psychology, 2nd Ed.

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Cognitive Psychology, 2nd Ed.

• Chapter 15
• Intelligence

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General Intelligence

• Intelligence Quotient (IQ)
• MA/CA x 100
• General intelligence (g)
• Biological measures
• -perceptual-motor RT
• -ERP complexity

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General Intelligence

• Fluid vs. Crystallized intelligence
• General fluid intelligence correlated with
  central executive functions of working memory.
• PET activation in left lateral prefrontal cortex
  for both spatial and verbal problem
  solvingindicative of central executive
  involvement.

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Criticisms of g

• Verbal IQ and Performance IQ are dissociated in
  aging.
• IQ tests measure linguistic, logical-mathematical,
  and spatial intelligence.
• Musical, bodily-kinesthetic, and intra- and
  inter-personal intelligence are ignored by IQ
  tests.

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Nature vs. Nurture in IQ

• Heritability (h2) Proportion of variance caused
  by genetic differences.
• Heritability correlation between identical twins
  reared apart (r h2).
• Heritability increases with age from .4 in
  childhood to .75 in late adolescence.
• Multiple genes, probabilistic effects

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Nature vs. Nurture in IQ

• Extent of parents talking with young children
  predicts verbal IQ.
• Deprivation, neglect, and abuse harm IQ but is
  there a threshold for normal development?

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Nature vs. Nurture in IQ

• Preschool programs (e.g., HeadStart) increases
  chances of finishing school.
• Deprivation, neglect, and abuse harm IQ, but is
  there a threshold for normal development?
• Flynn Effect Increase in IQ in industrialized
  nations of 3 points per decade since 1940.

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Sex Differences

• Understanding effect size (d mean difference
  divided by standard deviation)
• d .20 small
• d .50 medium
• d .80 large

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Sex Differences

• Verbal ability small advantage for females on
  some tests.
• Visuo-spatial ability small to large advantage
  for males, depending on the specific test (e.g.,
  mental rotation vs. spatial perception).

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Sex Differences

• Mathematical ability small to medium advantage
  for males, because of larger male variability.
• Navigation no sex advantage, but males use dead
  reckoning and females use landmarks.
• Motor Skills male advantage in throwing and
  female advantage in manual control movements.

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Reasons for Sex Differences

• Social-cultural males and females are
  socialized differently and conform to different
  cultural expectations. The degree of difference
  varies by culture.
• Biological Natural selection in Upper
  Paleolithic era (40,000 to 60,000 years ago) may
  have favored verbal and fine motor control in
  females navigation and throwing in males. Note
  brain lateralization in males.