Heredity & intelligence Flashcards
Heredity=
role of nature
Behavioural genetics=
the study of how/why inherited biological material influences behavioural patterns
>specifically “personality traits”
>broad patterns of behaviour
Calculating heritability: defining terms= (2)
> phenotype= observable characteristics of an individual based on their genes (height, eye colour)
Genotype= genetic makeup of a particular organism (contributes to phenotype)
Calculating heritability: Heritability quotient
○ Heritability is expressed as H^2= Vg/Vp
○ Heritability estimate= H^2
○ Variation in phenotype: Vp
○ Variation in genotype: Vg
Calculating heritability: heritability quotient> range>
> Heritability estimates a range from 0-1
- h=1 : all variation in population due to genotype
- h= 0: No variation due to genotype
HQs about populations, not individuals
Heritability & Twins> Genetic relatedness (4)
> monozygotic= gr of 1.0
Dizygotic= gr of 0.5
Full siblings= gr of 0.5
First cousins= 0.125
Heritability & twins> Intelligence> Bouchard & McGue, 1981> Literature review>
- lr of 111 worldwide studies comparing family members IQs
>MZ twins raised TOGETHER= 0.86
>MZ twins raised APART= 0.72
>DZ twins raised TOGETHER= 0.62
>Full siblings raised together= 0.47
>Full-siblings reared apart= 0.24
>cousins= 0.15
Heritability & Twins> Individual difference in personality> meta-analysis (Vukasovic & Bratko, 2015) (2)
- 62 studies, N=100,000
- results:
- found average effect size was 0.40/ 40% (due to genetics)
- thus: ID in personality were due to genetics, while 60% are due to environmental influences
Heritability & Twins> Individual difference in personality> meta-analysis (Polderman et al, 2015)
2479 studies, N=14 million+
>results= found a heritability of 49%
>all based on classic twin studies
Monozygotic twins & culture: individualistic vs collectivist cultures> (Segal & Hur, 2022) (3)
> south korean twins: accidentally separated as small children
1 adopted by US family
Two levels of differences:
>macro-culture= overarching societal culture
>micro-culture= family unit (US=strict; Korean=
supportive)
Monozygotic twins & culture: individualistic vs collectivist cultures> (Segal & Hur, 2022) Outcomes> (4)
> same scores:
- conscientiousness (high), (of note: as would assume
influenced by culture)
- same neuroticism (low)
- identical self-esteem scores
- high job satisfaction (despite different jobs)
Heritability myths: busted> (3)
- heritability coefficients reflect a set % of ones personality attributable to genes (not true)
- heritability coefficient tell you how much of YOUR personality is attributable to genes
- heritability coefficients from twin studies are accurate reflections of heritability in general (not true)
Implications of heritability> (2)
> Genes do matter:
-SOME aspects of personality comes from genes
Experience matters:
- much of personality does NOT comes from genes
Implications of heritability- (1) Genes do matter & (2) experience matters> study (power& pluess, 2015)
> big 5 & heritability: (for genetic influence)
-significant results for 2 traits: neuroticism (15%) & openness (21%)
big 5 & heritability: (against genetic influence)
-no evidence of heritability for either extraversion, agreeableness or conscientiousness
Gene + environment interactions>
- we have inherited “propensities” for certain activites (e.g. internal competitiveness & sport)
- “propensities” require an outlet for expression (i.e. context for enacting)
- twins & same interests= nature?
Heredity & disease>
> Genome-wide association studies (GWAS studies)=
- allow scientists to find genes associated with a specific
disease
still a lot of unknowns with heredity (hard to distinguish many nature/nurture influences)
What is intelligence?>
“ability to learn, understand and make judgements or have opinions that are based on reason”> (cambridge dictionary)
>can be defined through different mental abilities
Intelligence> (defining through) :mental abilities=
mental abilities= traits that reflect how well individuals can process various types of information
>(e.g. problem solving, critical thinking, planning, reasoning, learning, creativity, knowledge/recall)
Why study intelligence?> (3)
> Long believed to be important
-proficiency tests used in ancient China for emperor’s
officials
considered to be linked to life outcomes:
- help discover who will perform best on different tasks?
- help discover who will benefit most from more
training/education?
- can identify & alleviate problems (e.g. reconsider
historical stereotypes)
Early development of intelligence> Factor analysis & mental ability (spearman, 1904)>
invented “factor analysis” to study mental ability:
factor analysis=
Details of FA: assigned several “test” tasks, including:
–>visualisation
–>matching (colours/sounds)
–>ability to follow complicated instructions
–>mathematics
–>vocabulary
Early development of intelligence> Factor analysis & mental ability (spearman, 1904)> Findings>
found the various “test” tasks were all (generally) interrleated, known as:
-outcome: factor g (general intelligence)
Early development of intelligence> Factor analysis & mental ability (spearman, 1904)» Adjustment after exploring variations in performance>
2 factor theory:
1> general intelligence (g)= overall level of intelligence
2> specific ability (s)= specific to particular aspects of intelligence
Later development of intelligence> multiple factors (Louis thurstone: post 1936)
considered ‘g’ factor a bad idea, instead developed more advanced factor analysis of ‘multiple factors’
>proposed 7 primary mental abilities (based on inter-correlation technique)
Intelligence (later)> multiple factors (Louis thurstone: post 1936)> 7 primary mental abilities
- spatial reasoning
- Perceptual speed
- Numerical
- verbal relations
- word fluency
- memory
- inductive reasoning
