Mandy Part 2 Flashcards
The shared genes w diff types of relatives
1st degree e.g. parents, share 50%. Second degree e.g. grandparents share 24%, 3rd degree e.g. great grand parents share 12.5%
Galton, initial ideas of heritability
Intro idea of nature nurture, in relation to Darwin. Looked at ppl doing eminent things in newspapers and found no. Of eminant relatives greater for 1st degree than 2nd. Also looked at environment at royal society members and asked them about their upbringing. First to suggest twin and adoption studies
Variability defining one
If parents and child v similar, low variability and high prop of shared variance, opposite of different
Some traits 100% genetic, shared high and no variability but others differ
Diff ways of measuring
Behavioural approaches like family studies or dna approaches. Use behavioural to estimate heritability across populations W shared variance but not ind. say proportion of variance for intelligence due to genetics. Ridley 99: meta anal found more shared genetics, more heritability of intelligence e.g. mz twins, then twins apart, siblings. Eyesneck said 69% and bell curve 74%
Dna methods
Genome wide association study looks at total dna for one group, look for single nucleotide polymorphism (SNP) the variations that may occur in certain groups. Deary 2012- did the Scottish kids one also used lots of unrelated ppl and found heritability 38% but differs across life and culture. Davies 2011: found 40-50% variance linked to SNP they had in common. Deary, cox and bull 2021: lit review heritability is 20-30% (less than before)
Concepts definition for nature nurture ideas
Interactive not additive model, includes genetic variation, assortative mating, twin studies and environment. Abstract concepts: theoretical, don’t tell us about spec genes or environment variables. Population concepts: estimates for group, don’t say about ind
Types of genetic variance and assortative mating
Genes and environment = phenotype. dominant= either dom or rec. epistasis=genes interact w others to determine if they are expressed or suppressed. Add these all together- get broad heritabiltiy. Variation in traits is bc mating isnt random so may over/under estimate heritabilty
Environment
Bio (nutrition, lead, prenatal), fam environment, education, culture. Birth order and fam size: Belmont and marolla 73: as both increase, intelligence decrease. Fridges 2000: longit study in us found no link. Dodgers 2001: admixture hyp, resource dilution model-Galton, confluence model (not birth order but the changes that occur within the home). Bidirectional as iq predicts school but school helps iq (linked to implicit theories)
The bell curve - Hernstein and Murray
6 assumptions: G exisits, iq tests are accurate, iq tests match implicit theories, iq is stable and tests not bias, cog heritability no less than 40-80%. Suggested cog elite e.g. some go to college some don’t. Said intell more important than SESnfor predicting welfare. Higher iq of Asia in American Han black. Low iq women have more kids so pollut pop W low iq, say immigrants fault too and increases crime. To stop: don’t use affirmative action as lead to decrease intell but give resources to elite
Bell curve critiques
No consensus on G, iq tests not always accurate and shift between cultures, iq not stable. Tests may be unbiased but theories are. Heritability has a large range and can’t explain group diffs. Correlation isn’t causation for SES and intelligence (other factors), used self report to ask kids what SES they were. Said research showing black ppl as intelligent was inconsistent and removed it - karmin 95. Led to APA make task force led by Neisse - consensus that iq may differ across groups but not due to genetics
Background sex diffs in intell
Suggest men better bc brain bigger but research says no diff. Terman-Stanford binet show girls slightly better. Spear a no diff and court 83: systematic review found no diffs. But used narrative anal where just say if supports hyp or not and small samples. Lynn and irwing: did meta anal (compile samples together) found under 15 no diff, then bigger diff as get older in favour of males but not huge effect sizes
Evaluation
Nyborg 2005: advantage for males- supporting last also in meta But colom 2000 and spinath 2008 didn’t find any diffs-disputes.Dykiert 2008: and hunt and madhyastha 2008: reported diffs due to unrep samples as males more represented in the samples.Hyde 2005: comp review and found no diffs
Specific intelligence sex diffs
Maccoby and jacklin 74: men do better on spatial , women do better on verbal. Different meta anals find some diffs but more when younger. Small effect size that females better at verbal but not as robust evidence as for spatial diffs
Sex diffs in gifted children -Benbow and stanley 83
12-14 who took sat early. No diffs in verbal but boys did better in the maths section as 13x as many W scores of 700+, 4x scores over 600. But gap now closing as now 3:1 due to efforts to get women in harder maths and science
Bio explanations- brain size
Men’s 10% larger from adolescents onwards (explains old findings). But pietschnig 2015 mata anal found sig link between seize and intell but only small proportion of variance. Inflated due to republication bias