Both perspectives are over simplistic. They ignore the evidence that nurture can in fact override nature such as the ‘Brenda Brian study’ by Dr Money. Furthermore there is little evidence to support evolutionary claims. They are post-hoc explanations.
Empiricists, or rather ‘radical behaviourists’ hold the view that all behaviour is a consequence of experience alone. For instance, Skinner (1957) proposed that a child’s language is acquired through operant conditioning i.e. reinforcement via rewards and punishment, if they say something and is punished for it then obviously they will stop doing it, however, if they are rewarded for their utterances, then they will continue in saying it. The nurture debate can also be explain in a non-behaviourist approach. Bateson et al (1956) suggested that schizophrenia is a result of contradicting messages from parents (the ‘Double Blind Theory’).
Such views are also reductionist as they ignore biological evidence. When a mutant fly has a certain gene removed they are unable to be conditioned thus suggesting that learning itself is innate. In addition, Mineka et al (1984) found that it was easier to condition monkeys to fear snakes than flowers, supposedly because snakes posed as a survival threat to their ancestors. This suggests that conditioning can be affected by innateness.
The nature-nurture debate can be explored with the example of gender. Dr Money’s theory of neutrality suggests that all babies are born neutral – they are a ‘blank slate’ and that with sex reassignment and the appropriate environmental factors, gender can be reassigned. However, there is a critical period of 2 years.
An alternative explanation is that gender is pre-programmed before birth (Dr Diamond). Supporting evidence comes from a study where testosterone was injected into female foetuses of rats before birth. They found that the rats appeared and acted like males after birth e.g. they attempted copulation with female rats. Further research have found physical differences in the brain of both genders in both transsexual humans and rats. They named this the Sexual Dimorphic Nucleus (SDN).
However, the case of Brenda Brian disapproves of the nurture view. Brian, an Mz twin, was given sex reassignment surgery at 22 months old due to fatal circumcision errors. She was bought up as a girl and given hormones. But she was rebellious and had no friends. At the age of 14 she decided to live as a male and became David. This suggests that gender cannot be taught. However, Money argued that 22 months is too late and the presence of the other twin could have greatly affected Brenda.
A different topic in the nature-nurture debate can be seen in intelligence. Whether intelligence is biologically predisposed or is entirely taught. There is evidence for both sides of the argument. For instance, gene mapping studies have identified individual genes that are linked with high IQ scores (Chorney, 1998). Twin studies have shown that large variations in IQ is caused by genetic factors. Conversely, IQ scores have increased by 20 points globally for the past 30 years (Flynn, 1987) thus suggesting that intelligence can be affected by an increase in technology and media.
The fact that most people live in supportive families which in turn maximises the influence of genes and minimizes environmental factors can explain the strong genetic evidence. Whilst on the other hand a poor environment equates to small environmental changes to having a bigger impact. Turkheimer et al (2003) studied data of 350 children and found that variations in IQ of children of poor background were due to shared environment and found not genetic links (heritability 0.10). Rich families had heritability of 0.72. Therefore supporting the view that a poor environment will permit smaller changes to having a bigger impact on behaviour and the opposite for richer environments where emphasis is more on genes.
A more contemporary view on the debate is that biological and psychological factors are too entwined that it seems nonsensical to separate them. The diathesis stress model provides a reasonable explanation. It combines both nature and nurture and suggests that individuals may be more prone to illness due to genetic vulnerability but will only be triggered by environmental cue e.g. stress. Tienari (1994) found that adoptees schizophrenic biological parents only developed the disorder if the adopted family was rated as ‘disturbed’. In other words the illness was triggered only under appropriate cues. Therefore, nature and nurture coincide in influencing behaviour.
