The nature-nurture debate

• The nature-nurture debate


  The debate

  Nature

  Early nativists such as Descartes argued that human characteristics are innate : the result of heredity. Empiricists (Locke) argued that the mind is a blank slate at birth upon which learning and experience writes: the result of the environment. The heritability coefficient is used to assess heredity - a numerical figure ranging from 0 to 1.0 which indicates the extent to which a characteristic has a genetic basis (1 = genetically determined). The general figure for IQ is around 0.5 - suggests that both genetics and envi are important.
• The nature-nurture debate


  The debate

  Nurture

  The concept of nurture and environmental influences in psychology requires further clarification as 'the environment' is such a broad and all-encompassing concept. So Lerner (1986) identified different levels of environment. These may be defined in quite narrow pre-natal terms (e.g. the mother's physical and psychological state during pregnancy), or more generally through post-natal experiences such as the social conditions the child grows up in and the cultural and historical context they are part of.
• The nature-nurture debate


  Relative importance of heredity and environment

  In a practical sense, the nature-nurture question is impossible to answer because environmental influence in a child's life begins as soon as it is born (and perhaps even earlier). Nature and nurture are so closely intertwined that, practically and theoretically, it makes little sense to separate the two. E.g., in twin studies it is often very difficult to tell whether high concordance rates are more the result of genetics or shared upbringing. So recent focus of the debate has been on the contribution of both.
• The nature-nurture debate


  Relative importance of heredity and environment

  The interactionist approach - attachment patterns between an infant and its parents are often the result of a 'two-way street' in which the child's innate temperament will influence the way its parents respond to it, and their responses will in turn affect the child's behaviour. Thus nature creates nurture; heredity and environment interact.
• The nature-nurture debate


  Relative importance of heredity and environment

  Diathesis-stress model - suggests that psychopathology is caused by a biological/genetic vulnerability (diathesis) which is only expressed when coupled w/ a biological or environmental 'trigger' (stressor). Tienari et al. (2004) found that in a group of Finnish adoptees, those most likely to develop schizophrenia had biological relatives with a history of the disorder (vulnerability) and had relationships w/ their adoptive families that were defined as dysfunctional (trigger).
• The nature-nurture debate


  Relative importance of heredity and environment

  Epigenetics - refers to a change in our genetic activity without changing our genetic code. Aspects of our lifestyle and the events we encounter leave epigenetic 'marks' on our DNA. These marks tell our bodies which genes to ignore and which to use, and in turn, may go on and influence the genetic codes of our children and their children.
• The nature-nurture debate


  Relative importance of heredity and environment

  Epigenetics 2 - Dias and Ressler (2014) gave lab rats electric shocks every time they were exposed to the smell of acetophenone. As behaviourism predicts, they showed a fear reaction as soon as the scent was presented. The rats' children also feared the smell, even though they had not been exposed to acetophenone before or received any shocks. So did their grandchildren.
• The nature-nurture debate - evaluation

  Research attempting to 'tease out' the influence of the environment is complicated by the fact that even siblings raised within the same family may not have experienced exactly the same upbringing. The idea of shared and unshared environments (Dunn and Plomin 1990), suggests individual differences mean that sibling may experience life events differently (e.g. age/temperament could influence reaction to divorce). This is a limitation of the debate as it supports view that heredity and environment cannot be meaningfully separated.
• The nature-nurture debate - evaluation 2

  The notion that genes and environment interact is elaborated by constructivism. People create their own 'nurture' by actively selecting environments that are appropriate for their 'nature'. E.g., a naturally aggressive child is likely to feel more comfortable around children w/ similar behaviours and will 'choose' their environment accordingly, which affects their development. This is a limitation of the debate is it is further evidence that it is impossible and illogical to try to separate nature and nurture influences on behaviour.
• The nature-nurture debate - evaluation 3


  Scarr and McCartney (1983) - theory of 3 types of gene-environment interaction

  • Passive interaction - parent's genes influence how they treat their children (musically gifted = encourage engagement w/ music).
  • Evocative interaction- child's genes influence and shape the envi they grow up in (musically talented=will be picked for school concerts).
  • Active interaction - child creates its own environment through the people & experiences they select (choose similar, musically talented friends).

  Limitation - points to a complex/multilayered relationship