9.3 genetic and environmental influences on intelligence Flashcards
IQ scores are most similar for
- identical twins that are identical over fraternal
- identical twins raised apart have a more similar iq score than fraternal twins raised together
- biological siblings raised together is higher than adopted siblings raised together
heritability
of IQ scores is bw 40 and 80%
-that means, for any given sample of individuals, about 40-80% of differences in IQ scores originate from genetic differences
the contribution of genetic differences depends on the sample of individuals
heritability of IQ scores for a sample of wealthy ppl is > 70%
heritability of IQ scores for a sample of ppl living in poverty is about 10%
environmental influences
environmental influences will tend to be the dominate influence on any trait whenever there is variation in the environments that host our development
behavioural genomics
have revealed a group of genes that each seem to make a small contribution to our mental abilities
gene knockout (KO) studies
have identified a number of genes related to cognitive abilities in mice
-animals have a gene removed and then compared to animals that did not have that gene removed
transgenic studies
(the insertion of genetic material into animals)
have revealed genes that provide mice with cognitive benefits
environmental influences on IQ scores
many studies of humans and other animals have established a positive link bw mental abilities/brain complexity and the quality of physical and mental stimulation during early stages of development
-rats raised in active and stimulating environments end up with bigger brains that have more synapses
birth order and IQ scores
the 1st born child in a family tends to have statistically higher IQ scores than the 2nd born or 3rd born child
-maybe its bc older siblings often have some responsibility for taking care of their younger siblings and teaching them about things
socioeconomic status and IQ scores
children from wealthier families tend to have higher IQ scores than children from poorer families
socioeconomic factors related to cognitive development
by age 3, children of professional parents have been exposed to 30 million words, whereas children of working class parents have only exposed to 20 million words
a family’s wealth is positively correlated with:
the # of books, magazines and newspapers they own their access to computers
and the opportunities they provide for exploring the world outside of the home
a family’s degree of poverty is positively correlated with:
lower quality health care/nutrition degree of exposure to toxins stress and conflict inside the home
there is a known association between the quality of a person’s or animals diet and
their cognitive development
multiple sources of stress
tend to be more prevalent for poorer families
poorer neighbourhoods tend to be noisier, closer to sources of pollution and toxins, and have much higher violent crime rate and have greater difficulty finding adequate jobs for meeting expenses
financial stress in households causes more conflict among family members