Biological approach

assumptions

suggests everything psychological is firstly biological, so to fully understand human behaviour, we must look at biological structures and processes within the body

the mind lives in the brain, contrasting with the cognitive approach (sees mental processes of the mind as separate from the physical brain)

neurochemical basis of behaviour

the action of chemicals in the brain

much of our thought relies on chemical transmission in the brain, using neurotransmitters. An imbalance of neurochemicals has been implicated as a possible cause of mental disorders, e.g. low levels of serotonin in OCD and overproduction of dopamine in schizophrenia

genetic basis of behaviour

psychological characteristics e.g. intelligence, are inherited the same way as eye colour or height

twin studies are used to investigate whether certain psychological characteristics have a genetic basis, by analysing concordance rates - the extent to which twins share the same characteristic. If a characteristic is genetic we expect all identical (MZ) twins to be concordant (share 100% of the same genes). The same would not be true for non-identical (DZ) twins who share 50% of the same genes. In both cases the environment is assumed to be constant

genotype

genetic make-up

identical twins have different ones e.g. PKU - shows much of human behaviour depends on interaction between inherited factors (nature) and the environment (nurture)

phenotype

the way the genes are expressed through physical, behavioural and psychological characteristics

evolution

19th century - Darwin proposed natural selection theory. The main principle is that any genetically determined behaviour that enhances an individuals survival will continue in future gens.

Happens in a similar way to farmers deciding which animals to use for breeding: farmer selects the ones who possess desirable characteristics

in nature the selection occurs ‘naturally’ - no one chooses