Transcript Nature, Nurture and Human Diversity

Nature, Nurture and Human Diversity:
Temperament and Heritability
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
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?
Self-regulation
• Genes are self-regulating
– Conclusion – they react differently in different
environments
• We are all products of interactions
– Genetic predispositions and surrounding
environments
– Reciprocal determinism
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
Buss and Plomin’s EAS Temperament Survey
• Measures broad personality dispositions:
– Activity: person’s energy output
– Emotionality: intensity of emotional reactions
– Sociability: tendency to affiliate and interact
How to score
• Reverse the number placed in front of items 6, 18, and 19
(5=1, 4=2, 3=3…)
• 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
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
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
Conclusions
• Heredity may point personality in 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 child’s personality
Football Island
• http://www.youtube.com/watch?v=A69Z8fCp
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