This article is an introduction to the theory of personality that emphasizes the different evolution of reward and punishment mechanisms in the brain of vertebrates. The three brain/behavioural systems that are believed to underlie personality differences are: (1) the behavioural activation system, which represents sensitivity to reward cues, (2) the behavioural inhibition system, which is responsible for responding to punishment cues, and (3) the fight/flight system, which is related to unconditioned aversive experiences.
Gray believes that the dimensions of extroversion and neuroticism in Eysenck's theory should have (approximately) a 30-degree rotation, to form the two primary dimensions of anxiety and irritability. He also believes that the hypothesis derived from the theory of introversionextroversion, according to which conditioning is more in introverts, should give way to a belief that emphasizes the greater sensitivity of introverts to the signs of punishment and the lack of frustrating rewards.
