Debate: Nature and Nurture The degree to which human behaviour is determined by genetics/biology (nature) or learned through interacting with the environment (nurture)
Aims of lesson • To understand what is meant by the nature-nurture debate and to identify the main assumptions . • To be able to describe at least 1 study which supports nature, and 1 study to support nurture. • To be able to identify the perspectives/ approaches relevant to the debate.
Nature • Behaviour is caused by innate characteristics : The physiological/biological characteristics we are born with. • Behaviour is therefore determined by biology. • Determinist view-suggests all behaviour is determined by hereditary factors: Inherited characteristics, or genetic make-up we are born with.
Nature • All possible behaviours are said to be present from conception. • Genesprovide the blueprint for all behaviours; some present from birth, others pre-programmed to emerge with age. • Is a developmental approach: E.g. Piaget: children’s thought processes change at predetermined age-related stages changes in age are related to changes in behaviour.
Nurture • An individuals behaviour is determined by the environment- the things people teach them, the things they observe, and because of the different situations they are in. • Also a determinist view- proposes all human behaviour is the result of interactions with the environment.
Nurture • Behaviourist theories are nurture theories: - Behaviour is shaped by interactions with the environment. • Born an empty vessel- waiting to be filled up by experiences gained from environmental interaction. • No limit to what they can achieve: -Depends on quality of external influences and NOT genes. • The quality of the environment is KEY: -You can become anything provided the environment is right.
Support for Nature • Identical genes exist in Identical Twins- Monozygotic (MZ) twins share 100% of their genes. • Fraternal Twins- Dyzygotic Twins (DZ), share 50% of their genes. • Genetic effects can therefore be shown when the correlations within each group is compared with the correlations between each group. • This can be added to the correlations found with other relatives. Parents share 50% of genes, cousins share 12.5%.
Support for Nature Genetic basis of Schizophrenia (Gottesman & Shields, 1976) - A review of twin and adoption studies into schizophrenia between 1967 and 1976. - In adoption studies: compared biological parents and siblings and adoptive parents and siblings. - In twin studies: compared concordance rates (how often both twins were diagnosed with schizophrenia) for monozygotic (identical) and dyzygotic (non-identical) twins. Video
Support for Nature • Results - Adoption studies found increased incidence of schizophrenia in adopted children with a schizophrenic biological parent. - ‘Normal’ children fostered to a schizophrenic parent and adoptive parents of schizophrenic children showed little evidence of schizophrenia. - Twin studies found higher concordance rate for schizophrenia in MZ twins (58%) than DZ twins (12%). • Conclusion Significant genetic input into the onset of schizophrenia. Genes responsible for predisposing a person to schizophrenia.
Support for Nature • IQ scores -Plomin (1988) studied MZ and DZ twins reared together and apart and found that I.Q. has an overall heritability of 0.68- genetics are responsible for about 68% of the variation in I.Q. -MZ twins reared apart have I.Q. scores which correlate at about 0.74, or 74%. Evaluation point However, variations between identical twins must be due to environmental influences.
Support for Nurture – Little Albert • Classical conditioning of fear- phobia acquisition: ‘little Albert’ (Watson & Raynor, 1920) -Before the study little Albert showed no sign of fear response in any situation. Session 1: Aged 11 months, Albert was presented with a rat. Each time he reached for the rat a steel bar was hit. 1st time= he jumped + fell forward 2nd time= he began to whimper Session 2: after 5 paired presentations, Albert reacted to the rat alone by immediately crying, turning, and crawling away quickly.
Support for Nurture Session 3: Albert returned to see if the fear had transferred. - Presentation of toy blocks (neutral stimulus) = playing - Presentation of the rat followed by a rabbit, dog, fur-coat, Watson’s hair and a Santa Claus = –ve responses of crying, moving away from stimulus and crawling. Session 4: steel bar + rat, steel bar+ rabbit, steel bar+ dog. Fear response was pronounced in all. Session 5: 1 month later Albert continued to show fear reactions to all stimuli. Transference of the fear had been made to similar objects.
Support for Nurture • Conclusion - By session 2, after 5 paired presentations the conditioning of fear was evident: is possible to condition fear through classical conditioning. - By sessions 3 & 4, transference of the fear had been made to similar objects. - By session 5, time had not removed the fear response. • Provides evidence that the environment can be manipulated to create a phobic response & behavioural change. (See key study: A2 OCR textbook p.115)
Can you think of any other studies that show the effect a situation can have on behaviour?
Nature Nurture Interaction • Behaviour is often a result of the interaction between nature AND nurture. • An individuals characteristics may elicit particular responses in other people e.g. Temprament: how active, responsive or emotional an infant is influences in part determines their caregivers responses. Gender: people tend to react differently to boys and girls due to expectations of masculine and feminine characteristics. • Aggression: Displaying aggressive behaviour create particular responses from other people.
Nature Nurture InteractionEvidence • Rutter and Rutter (1993) Aggression hostility - Described how aggressive children think and behave in ways that lead other children to respond to them in a hostile manner. -This then reinforces the antisocial child’s view of the world. Thus, aggressive children tend to experience aggressive environments partly because they elicit aggressive responses.
Nature Nurture Interaction • Maguire et al. (2000)- Taxi driver study - Structural MRI scans of the brains of licensed London taxi drivers were compared with controls who did not drive taxis. - Hippocampal volume correlated with the amount of time spent as a taxi driver - The posterior hippocampi of taxi drivers were significantly larger relative to those of control subjects. - The posterior hippocampus stores a spatial representation of the environment and can expand regionally in people with a high dependence on navigational skills. See AS Psychology textbook: pp.68
Nature Nurture Interaction • Maguire et al. Conclusion - It appears the brain has the capacity for plasticity (the ability to change)- the structure of the brain can alter in response to environmental demands.
Problems with Nature-Nurture Debate • It is reductionist • It is deterministic • It is difficult to control variables Determinism: The ‘nature’ view of psychology is a determinist one- it suggests behaviour is determined by hereditary factors (e.g. IQ). Links to other debates
Applications Nature • Drug therapies can be developed to treat behavioural or psychological problems that have a physiological origin. E.g. SSRI’s can be used to treat depression, Ritalin- ADHD. Nurture • If behaviour is susceptible to environmental influences we need to consider how we adapt our environment. E.g. To promote helping behaviour, enhance learning, reduce aggression and decrease criminality. BUT- where does learning fit?? Nature like Piaget, or nurture like Skinner?
Summary • Nature: behaviour is caused by characteristics we are born with e.g. genetic, physiological. • Nurture: behaviour is shaped through interactions with the environment. • Research supporting nature: language development, IQ scores, predisposition to schizophrenia etc. • Research supporting nurture: fear acquisition, effect of the environment on behaviour.
Summary cont... • Nature-nurture interaction: Temperament and gender can influence other peoples behaviour. • Exposure to certain environmental stimuli can alter physiology e.g. Brain structure, neurochemicals. • Applications: Development of drug therapies, adapt environments to increase helping behaviour, enhance learning etc. • Link to other debates: Determinism