Nature, Nurture and Human Diversity: temperament and heritability

1
Nature, Nurture and Human Diversity temperament
and heritability
2
How stability of our temperament illustrates the
influence of heredity on development

• Temperament characteristic emotional
  excitability and intensity
• Relaxed and cheerful v. tense and irritable
• Ex emotionally intense preschoolers tend to be
  relatively intense young adults
• Compared with fraternal twins, identical twins
  have more similar temperaments

3
What is heritability and interaction of gene
environment on specific traits?

• Heritability extent to which variation among
  members of a group can be attributed to genes
• Heritability of intelligence 50
• Does not 50 genetic
• Does equal ability to attribute genetic influence
  on 50 of the observed variation
• Conclusion?

4
Self-regulation

• Genes are self-regulating
• Conclusion they react differently in different
  environments
• We are all products of interactions
• Genetic predispositions and surrounding
  environments

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Interactions

• Ex. 1 Stressful environments can trigger genes
  that affect production of neurotransmitters that
  underlie depression
• Ex 2 Breastfeeding boosts later intelligence
  only for the 90 of infants with a gene that
  assists in breaking down fatty acids present in
  human milk
• Ex. 3 A baby who is genetically predisposed to
  be social and easy going may, in contrast to
  another who is less so, attract more affectionate
  and stimulating care and thus develop into a
  warmer and more outgoing person

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Buss and Plomins EAS Temperament Survey

• Measures broad personality dispositions
• Activity persons energy output
• Emotionality intensity of emotional reactions
• Sociability tendency to affiliate and interact

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How to score

• Reverse the number placed in front of items 6,
  18, and 19 (51, 42, 33)
• Add scores for items 2, 7, 10, and 17
• Activity
• Add scores for 1, 6, 15, and 20
• Sociability
• Add scores for 4, 9, 11, and 16
• Distress emotionality
• Add scores for 3, 12, 14, and 19
• Fearful emotionality
• Add scores for 5, 8, 13, and 18
• Anger emotionality

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Women Men Women Men
Activity 13.40 12.80
Sociability 15.24 14.60

Distress 10.08 9.72
Fearfulness 10.60 8.92
Anger 10.28 10.80
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Findings

• Buss and Plomin
• Temperament is largely inherited
• Identical twins show more similar temperaments
• Correlations for identical were .63, .62, and .53
• Correlations for fraternal were .12, -.13, and
  -.03

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Conclusions

• Heredity may point personality in a certain
  directions but the direction is influenced by
  environment
• Highly emotional child is more likely than a less
  emotional one to become aggressive, parents who
  reward problem-solving skills over expression of
  anger may shape the aggressive child into a
  cooperative, altruistic adult
• Infants are NOT blank slates on which parents may
  write the childs personality