Gray's biopsychological theory of personality

One of the most widely accepted theories in terms of biological models in psychology is the biopsychological theory of personality proposed by Jeffrey Alan Gray in 1970. Gray hypothesized two systems controlling behavioral activity, the behavioural inhibition system (BIS) and the behavioural activation system (BAS). The BIS is thought to be related to sensitivity to punishment as well as avoidance motivation, while the BAS is thought to be related to sensitivity to reward as well as approach motivation.

Using psychological test scales designed to correlate with the attributes of these hypothesized systems, neuroticism has been found to be positively correlated with the BIS scale, and negatively correlated with the BAS scale.

The biopsychological theory of personality is similar to another one of Gray's theories, reinforcement sensitivity theory. The Biopsychological Theory of Personality was created after Gray disagreed with Hans Eysenck's arousal theory that dealt with biological personality traits. Eysenck looked at the ascending reticular activating system (ARAS) for answering questions about personality. The ARAS is part of the brain structure and has been proposed to deal with cortical arousal, hence the term arousal theory. Eysenck compared levels of arousal to a scale of introversion versus extraversion. The comparison of these two scales was then used to describe individual personalities and their corresponding behavioral patterns. Gray disagreed with Eysenck's theory because Gray believed that things such as personality traits could not be explained by just classical conditioning. Instead, Gray developed his theory which is based more heavily on physiological responses than Eysenck's theory.

Gray had a lot of support for his theories and experimented with animals to test his hypotheses. Using animal subjects allows researchers to test whether different areas of the brain are responsible for different learning mechanisms. Specifically, Gray's theory concentrated on understanding how reward or punishment related to anxiety and impulsivity measures. His research and further studies have found that reward and punishment are under the control of separate systems and as a result people can have different sensitivities to such rewarding or punishing stimuli.

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