Genetics of intelligence Flashcards
(21 cards)
Bouchard and McGue correlation findings
parent child - 0.42
siblings - 0.47
expected correlations for twins if IQ was fully genetic
MZ=1
DZ=0.5
how would we calculate a heritability estimate using twin studies
Double (MZ corr - DZ corr )
2x (0.76-0.49)=0.54
how has IQ heritability found to vary across IQ groups
-exploring how effects of genotype, shared and non shared environment interacted with SES
proportions of IQ variance attributed to genes and environment vary non-linearly with SES
low income vs high income IQ
low SES- 60% variance accounted for by shared environment
gene contribution close to 0
higher SES - opposite effect
what was produced in the bell curve
In USA, african americans score 15 points lower on average than white americans
what was the argument proposed for the bell curve
African Americans have lower IQ scores
IQ is highly heritable
lower attainment of African Americans is due to genetic differences between the races
why do heritability estimates contradict the bell curve argument
they estimate the % of differences in IQ that are caused by genetic differences
what did Howarth et al find about increasing heritability
effect oof genes on IQ increases from childhood to young adulthood
effect of shared and non shared environment on heritability decreases
what do Howarth et al findings suggest about intelligence development
course of development is guided by intrinsic scheduling of genetic programming
what does the Howarth et al study suggest about genotype-environment correlation
as people grow older they have more freedom to select, modify and create environments that match their genetic predisposition
self selected environment changes over time
what is the multiplier effect
genetic tendencies that guide behaviour will result in a change in the environment that magnifies the original tendency
what have GWAS found for IQ
not found common variants that explain much genetic variance
only a few relevant genetic loci have been discovered
how do SNPs play a role in genetic differences
100,000 SNPs in human studies
where DNA differ from the most common nucleotide in that position
what did Davies et al find about genetic effects on personality
11,600 significant SNPs
434 independent SNPs
709 genes found to be associated with intelligence
what percentage of variation was accounted for by SNP variation
25%
what were the genes for IQ suggested to do
related to the development of nerve cells and the nervous system
some appear to be related to health
what genetic correlations were found between traits and illnesses
positive genetic relationships between autism, brain volume ect
same genetic variants that are related to larger brains are also related to higher IQ and autism
how has nerve conduction velocity been found to correlate with g
measured by applying burst of current through the skin over a nerve and picking up time arrval further down the nerve
good correlates with IQ
how has inspection time been found to correlate with g
pattern for a short period of time followed by a mask
you have to identify it as one of two possible shapes
high IQ ppts are faster
correlates of g and reaction times
ppts asked to press buttons corresponding to zero
requires high cognitive ability
higher IQ times=faster reaction times
