In order to establish the effects of nature and nurture on personality, its is important to understand what is meant by this. We will look at different research methods on this subject and look at how this can effect our personality. Human behaviour is a term that refers to all of the things that people do; there are many theories that try to answer this question of why we do these things. Some theorist believe that we are a product of our genes and that our personalities are a result of our biological make up, whilst others believe that our environment; physical, social and cultural, has an effect. What is important to remember is that we are not looking for one particular answer here, i.e., nature has an effect on our personalities and nurture does not, we are looking at how nature and nurture work together to determine who we are.
Hans Jurgen Eysenck, (Book 1, Chapter 5) developed a type theory, believing that type of personality is determined by biology, he believed that putting people into the following categories could summarise the main personality dimensions. These were extraversion-introversion and neuroticism-emotional stability, and finally the addition of psychoticism-superego. Eysenck devised a psychometric test for measuring personality, known as the Eysenck Personality Questionnaire.
One of the key categories in his research is the cause of extraversion-introversion, he believed that there were individual genetic differences in cortical arousal (which is controlled by the ascending reticulocortical activating system (ARAS) thought to be involved in alertness and arousal) resulting in us being either introvert or extrovert. The Limbic system is the part of the brain that organises responses and is the biological basis of the neuroticism-emotional stability side. Eysenck did not expand on where psychotisim came into it.
Eysenck believed these three personality traits were key to making up our personalities. Along with the psychometric evidence for the way personality is structured, there is also physiological evidence, for example depressant drugs can make introverts less aroused, thus making them behave like extroverts (nature and nurture working together here). Eysenck clearly believed the differences in brain structure were inherited and played a significant part in our personalities and that a huge part of our personalities is made up genetically. Although Eysenck’s theory has many gaps in it and some of the evidence is weak, his theories have generated other personality research. There are other ways that the effect of genetics on personality can be studied; these include molecular genetics, temperament in children and the twin, family and adoption studies of behaviour.
Working alongside genetics is our environment, and whilst Eysenck claims a large part of our personalities is genetically made up, the environment (nurture) plays a large part too. From an early age our personalities are shaped by our carers, if we look at the observation by stern (Book 1, Chapter 5) we see the mothers tuning (maternal responses to an infants mood that provide an experience that the infant can use to self-regulate its mood) to the child’s reactions in an understated manner. The mother confirmed this was because she believed her son to be quite passive and did not want him to turn out like his father. She was therefore unconsciously trying to shape her sons personality. It is not necessarily so that two children growing up in the same family unit will develop the same, lots of things need to be looked at, for example first born babies will undoubtedly be treated differently to a third or forth born, children learn differently and whilst one sibling may require rewards in which to shape behaviour, the other may require punishment.
The emphasis on social acceptance from one family to another can be extremely different, but the ways in which the cultural and social issues are impeded on the child can have effects on personality and identity thus shaping who we are. Once personalities are developed, we then express our personality. The Stanford Prison Experiment (Book 1, Chapter 5) was conducted by Phillip G Zimbardo in 1975 to investigate the effects on behaviour of participants engaging in a role-play situation in a mock prison. Although now highly controversial, this experiment is clear evidence of the effect of environment on personality.
18 college students were split into two groups randomly, one group were assigned roles as prisoners and the other 9 were assigned as guards. The experiment was to run for two weeks with three guards working three 8 hour shifts and the prisoners were housed in three small cells each occupying three prisoners. After only 36 hours of the experiment one prisoner became acutely emotionally disturbed, and experienced uncontrollable crying and rage – his identity with the role was affecting his personality.
Interestingly, the other participants did not attempt to intervene to help this participant who was clearly distressed, instead they remained within roles, thus not allowing this to affect or shape their environment. As the experiment progressed a number of the guards became what was described as ‘sadistic’ and abuse of prisoners by guards was occurring through out the night when the participants thought there was no researchers watching! Here we have normal, mentally healthy men taking on extreme roles, (all participants had undertaken tests prior to the experiment) displaying traits of personality that no-one had predicted. The study was brought to early close.
To summarise, we see that nature and nurture interact with each other and is not fixed. There is evidence from Eysenck’s Personality Questionnaire that our genetic make up can affect our personality, although there are weaknesses in his evidence. Through psychometric testing and physiological evidence, Eysenck’s type theory illustrates the biological affects on personality. Maternal environments as seen by the mothers tuning in Sterns observation have an effect on developing personality from an early age. Expression of personality is evident in The Stanford prison experiment conducted by Zimbardo, where we see the huge impact that role-play has on personality. What is clear from the evidence is that nature and nurture affects who we are.