Nature Nurture Debate

• Nature- Innate charcteristics that come from within, that are passed on through our genetics
• Nurture- Environmental influences on our development and behaviour i.e. those that are external
• Nativism- Our thoughts and behaviour are subject to genetic influences (Descartes)
• Empiricism- Information and knowledge and therefore ultimately behaviour/personality were the result of social forces external to the individual
• Interactionism- The view that both nature and nurture are essential for any behaviour and therefore cannot be exclusively attributed to the environment or genetics
• Relative Contributions- The difference between two people's behaviour (or any physical characteristic) whether it is mostly due to inherited factorsor is mostly due to environmental factors. The idea that it cannot be specifically identified how much a particular characteristic is down to either the environment or genetics but instead the contributions that they make to cause individual differences

• Main method of assessing the relative contributions of hereditary and environment to differences in behaviour
• Heritability estimate- because and individual's behaviour is a result of an interction between genetics and the environment, twin studies cannot identify which one is the most important in the case of individual, instead they provide a heritability estimate- this is a statistical estimate tp show how much the differences in a specific trait in people is dow to heritability, rather than environmental factors
• These are studies carried out on monozygotic (MZ) and Dizygotic (DZ) twins
• MZ's share the same genes whereas DZ's only share 50% (the same as ordinary siblings), therefore if MZ's reared together are more alike to DZ's reared together, then increased similarity must be genetic, the degree of agreement is expressed as a concordance rate
• It has been suggested however that MZ's share a different environment to that shared by DZ's. investigators have therefore studied MZ's who were seperated in early life meaning that any similarities found would be purely genetic
• Bouchard and McGue- studied intelligence in MZ and DZ twins when reared apart compared to when reared together and found MZ twin have the highest concordance rates even when reared apart and compared to DZ's that have been reared together. Such findings suggest a clear genetic influence

• If an adopted individual is found to be more similar to their biological parents than to their adoptive parents, this would suggest genetics are more influential than environmental factors
• E.g. Kety et al found that of the 66 parents traced of a sample of 33 schizophrenic adoptees, 37 had schizophrenia of which most were the biological parent

Implications

• Findings from studies on intelligence, schizophrenia and aggression have practical implications
• If genes are largely implicated in difference in intelligence, this raises the question of whether it is worth investing time into enrichment programmes
• If the environment is implicated with schizophrenia, this could lay burden on the family
• If aggression is considered to be a product of the environment, this places burden for the control of behaviour on society

• The finding that even MZ twins when reared together don't have 100% concordance rates, has prompted for psychologists to look at the non shared environment
• This is the idea that even individuals from the same home will have different experiences due to different friendship groups, hobbies, teachers or the fact that experienced (siblings) events at different ages e.g. the death of a grandparent when one child is 10 and the other is 3 suggesting that the same experiences may have a different effect depending on the child's age

• A possible reason why unshared environmental influences were neglected unitl recently is that they interact closely with genetic factors as not to be easily recognised
• Belsky and Rovine- suggested that children with different temperaments present different challenges to their caregivers which determines the responses given from the caregivers and these responses change the environment for child. Therefore two children brought up in the same home and seemingly same environment may in fact create their own uniquely different environments. This suggests that children create their own microenvironment which is related to its own innate characteristics
• Flanagan- 'Nature creates its own nurture'

Constructivism

• The view that human experience is a construction of reality. Individuals shape and actively create their own experiences
• Plomin- People shape and selct environments well suited to their natures--> niche building
• It is not possible to define the environment independently of the person e.g. of two sisters one may be more academic and so the friends that she has will share the same academic interest
• People are seen as marking their own environments- attaching their own meaning to events, contradicts behaviourism (passive recipient of environment)

• Aim: To investigate the effects on perceptual processing of being reared in a resticted visual environment
• Method: Newborn kitten were placed in drums that had either vertical of horizontal lines on the walls, the floor was made of glass reflecting the patterns of stripes. The kittens were fitted with collars around their necks so that they could not see their own bodies. At five months, the kittens were tested for line recognition
• Results: Those who had been brought up in the vertical world acted as if blind to a horizontal world: for example, they would trip over ropes. Conversely, those brought up in the horizontal world acted as if blind to a vertical world e.g. chair legs. the behavioural blindness was mirrored by physiological blindness. Microelctrode recordings confirmed that the cells in the visual area of the brain only showed an elctrical response to the orientation experienced by the kitten
• Conclusion: Such findings suggest that the environment is important in the development of innate systems
• Evaluation: The study has been criticised on ethical grounds

• An inherited disorder and an example of the interaction between hereditary and environment
• People with PKU are unable to metabolise phenyulalanine (a protein everyday foods), instead they break it down into a substance poisonous to the nervous system, resulting in brain damage and intellectual retardation
• Genetical factors are strongly implicates due to the fact that the problem can be traced onto a pair of genes
• if the disorder can be detected at birth. the individual can be placed on a phenylalanine-free diet, rsulting in normal development
• Although PKU is hereditary, it is not possible to seperate nature and nurture

• Psychoanalytic- Stressed the biological nature of human beings, focuses on the instinctual drives of sex and aggression which are expressed withing the restictions of society. the response from significant others to the child's attempts to satisfy biological urges, produces long term effects on personality e.g. fixation. Acknowledged the indluence of the environment but also focused on the innate psychosexual stages
• Behaviourism- Placed great emphasis on nurture, behaviour is seen as being directly shaped and controlled through associative learning and the consequences of behaviour
• SLT- Stress the role of the environment on a person's behaviour with little attention paid to biological causes. Differ from radical behaviourists in acknowledging that environmental factors are not the only influence on behaviour proposing the idea of higher-level cognitive processes, such as the individual's appraisal of the situation which has effect on their behaviour in response. Considers the interaction between the individual and the environment
• Cognitive- Interactionist in their approach. Focus on innate information processing abilities that are constantly refined by experience e.g. piaget described the stages of cognitive development as determined by nature but the order of stages is invarient and roughly related to age

• Humanism- Both nature and nurture have roles in determining behvaviour and setting the boundaries withing which one is free to develop. The need to self-actualise is innate however the environmental factors determine how possible this is e.g. receiving unconditional positive regard will allow fulfillment to occur
• Biological- There is a continuing interaction between nature and nurture. Although the focus is on hereditary, the interaction with the envrionment is still considered e.g. Blakemore and Cooper illustrate the plasticity of the visual cortex. this shows how nature interacts with nurture