Who was the first to differentiate between the influences of nature and nurture?
Francis Galton
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What did he observe?
eminence seems to run in families
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What was Francis Galton's stance on the nature vs nurture debate?
Nature prevails over nurture
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Define eugenics
The scientifically inaccurate theory that humans can be improved through selective breeding of certain populations
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Which types of intelligence increase steeply during childhood?
fluid and crystalized intelligence
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What happens to fluid and crystalized intelligence after childhood?
Crystalized intelligence continues to rise, from the mid-twenties fluid intelligence declines
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Who studied the stability of intelligence across the lifespan and when?
Deary et al 2013
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What did Deary et al 2013 find in relation to the stability of intelligence across the lifespan?
It is one of the most stable behavioral traits and that one of the biggest predictors of being smart in old age is being smart at a young age.
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What was the correlation that Deary et al found between IQ measured at ages 11 and 90?
r=.54
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What is heritability?
A measure of how well differences in genes account for differences in peoples' phenotype (50% heritability = genes account for 50% of the variation in intelligence in the population)
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Name the three ways heritability can be studied
can be studied using family studies, twin studies and adoption studies
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What are family studies?
assess resemblances between family members on certain characteristics as a function of their degree of relatedness
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What are twin studies?
Behaviors are compared across monozygotic and dizygotic twins as a naturally occurring manipulation of shared genetic makeup
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What are adoption studies?
comparisons drawn between bio parents, adoptive parents, and adopted children
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Who studied the heritability of intelligence via twin, family and adoption studies simultaneously?
Plomin et al 2004
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What were the correlations Plomin et al found for MZ together, MZ apart, DZ together, Siblings together, and Siblings apart?
86, 72, 60, 47 and 24
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What else was found in Plomin et al's 2004 study?
family, adoption and twin data showed a heritability estimate of around 50%
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What conclusions can be made from Plomin et al's results?
1. As genetic similarity decreases, so do correlations with intelligence (FOR nature) 2. when twins/ siblings are raised apart, the levels of IQ similarity are reduced (FOR nurture)
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Who studied the heritability of intelligence across the lifespan and when?
Haworth et al 2010
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What did Haworth et al 2010 find?
The heritability of intelligence is not the same at different ages and intelligence is one of the most heritable behavioral traits
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What did the finding that heritability is not the same at different ages suggest?
Suggests a gen-environment interaction with a transition from more nurture to more nature
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What are the three main issues with the heritability of intelligence?
representativeness (adoption studies and twin studies make up large proportion of research) (issue as adoption families higher SES and MZ twins more similar environment than DZ) (atypical from norm), complexity of genetic influence (dont know how genes pr
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Define assortative mating
the tendency to mate with those similar to ourselves
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Who studied assortative mating and when?
Watson et al 2004
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How did Watson et al study assortative mating and with whom?
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