Nature vs Nuture debate - 2 not independent - Gene & Environment interact - Influences on development NOT predetermining factors.
Behavioural genetics vs Evolutionary genetics - different levels of explanation.
MZ twins do not have same persoanlities or same behaviours - Interaction between genes and environment is epigenesis.
- Genes - basic units
- Alleles - formed from genes
- Phenotype - observed characteristics
- DNA into chromosomes.
- Genes carry protein codes
- Genetic variation can be through mutation - mistakes in DNA copying
Types of Studies
3 classic techniques -
- Family Studies - differences between relatives
- Adoption Studies - Adoped child compared to biological vs adopted
- Twin Studies - MZ & DZ twins.
Basic technique to correlational studies with concordance rates. eg) Concordance rates for schizophrenia is 4x higher for MZ than DZ twins so complez metal disorder could be hereditary.
Heritability - percentage observed in population.
- Refers to groups NOT individuals
- Doesn't show extent of possible modifiable characteristic.
- Changes across lifespan
Influence of Genes on Development
Genes can be manipulated through selective breeding
TYRON - 21 generations of breeding maze-bright and maze-dull rats.
COOPER & ZUBECK - Bred maze-bright & maze-dull in enriched and impoverish environments. Found maze-dull rats in enriched environment did as well as maze-bright. Suggest environment can overcome genetics.
Atypical development -
- Phenylketonuria (PKU) - Single gene defect - fixed by altering environment and diet low in phenylamine.
- Williams Syndrome - Multiple gene defect - Leraning difficulties - different cognitive processes are used.
Predetermined epigenesis - encoding for genes that are triggered by environment.
Influence of Genes on Development 2
KARMILOFF-SMITH - gene-environment interaction is complex. Likely that genes contribute to pathways being followed.
Developmental plasticity - different developmnetal routes possible.
Environment - anything not genetic ie) childhood illness - Environment can be product of genetic influence.
Genotype-environment interaction - genetic sensitivity to environment (PKU?)
Influence of shared environment lessens over time, unshared environment (differences in family etc) becomes more important.
Ethical Issues - testing for genetic disease which can't be cured, risks in gene therapy trials, genetic modifications, embryo selection. Guidelines by Nuffield Council on Bioethics
Evolutionary Developmental Psychology
Explain phenotypical characteristics in functional terms. key principles:
- Variation - in physical & psychological characteristics.
- Heredity - heritable characteristics
- Selection - Promoting survival.
Evolution is slow so Environment of Evolutionary Adaptedness (EEA). has problems which are solved by genetically specified modules which unlie behaviour.
Evolutionary developmental psychology - uses evolution to explain child develpment - Bowlby and attachment theory as mechanism to promote caregiving.
Genetic deteminism - importance of environment - HOWEVER - lacks empirical support, can't test, lacks applicable outcomes
GREARY & BJORKLAND - natural selective resulted in cognitive & social traits to promote surivival
Evolutionary Developmental Psychology 2
- Some behaviours useful in young get lost - eg) sucking for breastfeeding. Trying to get rid of them early can be counterproductive - ALS - suggests it can lower IQ.
- Immaturity useful - RATNER et al - egocentrism leads to better memeory & learning. BANDURA - child overestimate ability which leads to them trying harder tasks. Restricted capacity for working memory leads to chunking which allows quicker learning.
- Manay behavioural mechanisms eg Gender difference - preaparation for adulthood - high agression in boys for defending mate, rough and tumble for social hierachy, doll play for mothergood, boys have better spatial awareness for hunting, girls better memeory for foraging and remembering where things are.
Some adaptations are domain-specific & others are domain-general.
Evolutionary Developmental Psychology 3
Child friendships - reciprocal & symmetry, interact more with those phenotypically similar.
HUMPHREYS & SMITH - Agressive child finds similar, dominance hierachy.
BERNDT & LADD - Closer friends have similar interests & personality.
Theory of mind is crucial to social interaction. BARON-COHEN - 4 seperate interacting modules by 4yrs most children have all 4, understanding others beliefs & wishes although different to own.
Autistic child has different mechanism therefore do well on non-social tasks.
Westermarch effect - no sex interest in children raised together to reduce inbreeding, now maladaptive when non family members raised such as in Kibbutz.
Evolutionary Developmental Psychology 4
Evolutionary Psychology criticised for underestimating culture & learning.
PINKER - learning possible through innate mechanisms and genetic transmission result in complex human culture. Teddy bear become more human looking in response to adult prefernces.
Ideas mostly specultaive, lack of applications
GREARY - difference between the sexes should be taken in to account when teaching maths.
- Uses natural experiments, family, twin and adoption studies, ideas can't be tested.
PERSPECTIVES: NATIVISM & CONSTRUCTIVISM
- Strong nativist approach, Genes does not necessarily mean fixed, Nativist ideas difficult to test.