wk2+3 Flashcards
genotype
genetic complement, coded in DNA that we inherit from our parents
phenotype
outward manifestation of the individual
heritability
proportion of the phenotypic variance that is due to the genetic differences
environmental influences
family environment
shared environment
non shared environment
shared environment
Children raised in the same home will be more similar
non-shared environment
Even children raised in the same home will have different experiences growing up
galton (1865)
demonstrated consistent intellectual and creative leadership
- relationship between eminence and families
- also looked for an environmental explanation
- Intelligence is genetically determined and fixed at birth
Family studies
investigates the similarity of family members in respect of intelligence
1st degree relatives
Parents, siblings, children (50% genetic similarity)
2nd degree relatives
Grandparents, grandchildren, aunts, uncles, nephews and nieces (25% genetic similarity)
3rd degree relatives
Great grandparents, great aunt, great uncles, first cousins (12.5% genetic similarity)
twin types
MZ - Identical genotype 100% genetic similarity
DZ - Genetically no more alike than other siblings 50% genetic similarity
twin studies
- if the environment is the most important factor MZ and DZ twins will be equally similar
- if genetics and most important MZ will be more similar than DZ
twin studies correlation
- MZ - 0.87
- DZ - 0.53
The Burt affair
twins separated at birth more genetically similar
minnesota study
100 sets of DZ and MZ twins separated at early life. reunited as adults
g = influenced by genetics
MZ - 0.7
twin studies ✖️
- some MZ found to be living in different branches of the same family
- participants difficult to recruit
- selective placement (placing children in an environment as similar to their birth one as possible)
- pre natal environment has an impact
- mainly focused on middle class
- twins may not be representative of general population
virtual twins
reared in same environment with no genetic link
21 pairs of virtual twins tested
correlation 0.17 lower than MZ, DZ and siblings
fullerton virtual twins
completed suB-scales from WISC-III
correlation 0.3 at time one and 0.11 at time two.
modest relationship to no relationship
importance of shared genes over shared environment increases over time
adoption studies (1)
Loehlin et al 1994
environment influences intelligence when children are small but as they develop influence of environment decreases and genetics increases
adoption studies (2)
but studies investigating adoption of children from families living in poverty to middle-class families indicates Childs IQ 10/15 points higher than birth mother
Galton
1st to emphasise humans differ in intelligence and it’s hereditary nature
Binet
created the first intelligence test
used to identify a Childs mental age
Terman
adapted the test for children 4-14
led to standardised testing (assessing one child by comparing them with other children)
Stern
used Binet’s test
developed intelligence quotient (IQ)
(mental age/chronological age)x100 = IQ
Yerkes
tested intelligence of soldiers
Alpha and Beta test
Spearman
developed general intelligence ’g’
tests school kids analysed relationship between different tasks
if a person did well in one task they would do well on other tasks
specific abilities ‘s’ (e.g. vocabulary intelligence)
general intelligence ’g’ underpins all intelligence abilities
deviation IQ
actual test score/ expected test score for that age
Raven’s progressive Matrices
designed to minimise the influence of language and culture
making use of primarily non verbal problems
Thurstone
challenged Spearman
argued it just showed tests correlates positively
‘g’ results from primary mental abilities
Cattell
g = fluid intelligence and crystallised intelligence
Fluid intelligence
an innate capacity. it is a basic reasoning ability applicable to a wide range of problems
declines with age
affected more by brain damage
largely inherited
Crystallised intelligence
reflects schooling and cultural learning
Gardner
multiple intelligences verbal-linguistic logical-mathematical visual-spatial bodily-kinesthetic musical intrapersonal interpersonal naturalist existential
The flynn effect
Year on year the average IQ scores deadly increases
only measuring a limited range of cognitive abilities
causes of the Flynn effect
- environmental boost-better nutrition
- improvements in schooling
- modernisation
- testing attitudes and familiarity with testing
- tests no longer measure IQ
bell curve controversy
east asians score 5 point higher than white americans
white americans score 15 points higher than black americans
why was the APA task force required
identify and summarise relevant research on intelligence
“do various ethnic groups display different patterns of performance on intelligence tests - if so what might explain those differences”
there is no support for genetic interpretation. at present no one knows what causes the ethnic group variations in intelligence.
alternative explanations for ethnic variations in intelligence
- cultural bias (tests decided by white middle class individuals)
- stereotype threat self fulfilling prophecy
- socio economic disadvantage affects the educational performance of children from different ethnic group
- black american children placed in white SES homes during first year score high on IQ tests
genetic explanations
hard wired differences. some groups are naturally disadvantaged in competing for resources and doing well in life
environmental differences
society is unfair towards certain groups
test bias
IQ tests are designed to favour certain groups
group differences
race is not meaningful from a scientific perspective
variation within ethnic groups far outstrips those between groups
the gender gap
historically- men are more intelligent than women
IQ tests found no differences
men do 3-5 points better on full IQ test
women do slightly better on verbal tests
men do better on spatial tests
men and spatial tests
men need to know their surroundings to hunt and travel to fight
females with more testosterone do better on spatial awareness
