INTELLIGENCE

Question 1

HERITABILITY OF INTELLIGENCE

Answer 1

BEHAVIOURAL GENETICS:
= genetic [nature] vs environmental [nurture] influences on behaviour
= Heritability estimate [h2] - the proportion of total variance attributable to genetic variation across a population

METHOD FOR ASSESSING GENETIC HERITABILITY OF INTELLIGENCE
Twin Studies
= Conceived by Galton [1869] but not conducted until 1920s
= Twins are experiments of nature - MZ and DZ
= Plomin and Spinath [2004] review of studies with over 10,000 pairs of twins - average MZ correlation [r = .86] average DZ correlation [r = .60]

Adoption studies
= Approaches taken - twins reared apart, adopted apart siblings, adoptive siblings, adoptive parent-offspring pairs
= MZ share more similar environment than DZ twins and siblings - overestimation of genetic influence
= Adoptive environments are likely to be of higher socioeconomic status

Question 2

GENETIC HERITABILITY

Answer 2

DIFFERENT TYPES OF GENETIC VARIANCE
= Additive genetic variation - total of individuals genes inherited from parents
= Dominant genetic variance - certain genes are expressed and others are not [dominant/recessive]
= Epistatic Genetic Variance - Interaction between genes
= Assortative Mating - Selection of a partner who possesses similar genetic characteristics

Intelligence should be considered as an interplay between rather than the sum of our genes and environment

Question 3

ENVIRONMENTAL INFLUENCES ON INTELLIGENCE

Answer 3

Biological Variances and maternal Effects

Family environment

School and education

Culture

Question 4

SEX DIFFERENCES IN INTELLIGENCE

Answer 4

MALE BRAIN
= Targeting - 1.5 standard deviations
= Three-dimensional mental rotation - 1 SD
= Male brain specialised for building and understanding systems

FEMALE BRAIN 
= Women better at accessing LTM
= Better judges of character
= More verbal, observant, meticulous and industrious
= Hard wired for empathy

Evolutionary perspective on male superiority on spatial ability
= man as hunter, woman as gatherer

FUNCTIONAL AND STRUCTURAL BRAIN DIFFERENCES
MALES:
= 45% more grey matter
= 4% faster nerve conduction velocity
= Larger brains relative to body size
= More neurons

FEMALES 
= 84% of IQ related grey matter in frontal lobes
= More IQ related white matter
= Smaller brains relative to body size
= Less neurons
= More inter-hemisphere connectivity

HORMONES
Testosterone and estrogen play a role in sex-typical cognitive abilities

STEREOTYPES
Influence of stereotypes on sex differences
= within education
= outside of education
= interactions between technology and socio-economic status and their influence on intelligence in the classroom