A Discussion on Whether Only Biology Can Provide an Adequate Explanation of Personality

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A Discussion on Whether Only Biology Can Provide an Adequate Explanation of Personality

How an individual will tend to react in certain conditions is defined as their personality. Although the environment is constantly changing and therefore behaviour changes, personality is considered as a constant factor that causes the stability of behaviour over a period of time. Some argue that due to the consistency of personality it must be hardwired into our biology (Eysenck, 2006), others believe it is the interaction with the environment that shapes personality (Sturaro, Denissen, van Aken, & Asendorpf, 2008) and some argue personality differences are linked to evolution (Buss, 2009). This paper will provide a brief discussion on whether biology alone can provide an adequate explanation of personality and individual differences.

One of the first theorists to suggest that personality can be linked solely to biology was Hans Eysenck (Maltby, Day, & Macaskill, 2009). By using factor analysis Eysenck, (2006) suggested that all personality traits can be broken down into the two super traits of Extroversion-Introversion and Neuroticism. His theory is that individuals exhibit responses to external and internal stimuli and their responses will vary based on the intensity of the stimuli, and it is these responses that define personality traits. These responses to stimuli were originally suggested by Pavlov when he demonstrated that conditioned dogs prepared to eat when a bell was rung even if there was no food provided (Pavlov & Anrep, 2003), and it was Pavlov’s work that helped shape Jeffrey Gray’s contribution to another biological theory of personality (P. Corr & Perkins, 2006). Gray suggested that there are the two mechanisms of the behavioural inhibition system (BIS) and the behavioural approach system (BAS), with the BIS being activated by stimuli from negative reinforcement and the BAS being activated by positive reinforcement. He suggested that these mechanisms were situated in the septohippocampal system and the ventral striatum and both these systems can be seen to be activated by autonomic nervous activity and hormonal secretion (Fowles, 2006). Eysenck’s and Gray’s works are very complimentary in explaining a biological basis to personality and some might even argue that without Eysenck’s work it is difficult to see how Gray’s work would have led him to his Reinforcement Sensitivity Theory (RST) of personality (P. J. Corr, 2008).

To assist elucidation on whether biology can explain personality one of the methods that researchers typically use to demonstrate heritability of personality is the use of sibling and family studies. Siblings, with the same parents, share 50% of their genes, therefore it would be expected that they should share some personality traits (Maltby et al., 2009). Additionally, some researchers suggest assertive mating could play a part in providing siblings with similar personality traits as individuals tend to mate with a partner with similar personalities to themselves, and therefore the children would have an even greater chance of inheriting similar personality traits. However, it could also be argued that if the parents have similar personality traits then the children are in an environment where the personality traits are more prevalent, so environmental issues cannot be discounted.

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Twin studies are probably the most important form of study to researchers in their efforts to use biology to explain personality due to the identical genetic make-up of monozygotic twins researchers hypothesise that their personality would also score very similarly. Floderus-Myrhed, Pedersen, & Rasmuson, (1980) were such researchers who conducted a study on 12,898 same sexed Swedish twins, who were born between 1926 and 1958, to assess heritability of the personality variables of neuroticism and extraversion based on the Eysenck Personality Inventory. They found that dizygotic twins had a higher level of shared variance than the monozygotic twins for both neuroticism ...

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