Gray’s theory of personality is framed within the biological and factorial paradigms ; this means that it explains the differences between individuals from variables related to the nervous system and that it is based on the grouping of different personality traits in higher dimensions through statistical analysis techniques.

In this article we will analyze the main aspects of Gray’s model. Specifically, we will focus on the two basic personality factors and the two associated physiological mechanisms described by this author: anxiety and the mechanism of behavioral inhibition and impulsivity and the behavioral approach.

Jeffrey Gray’s Personality Theory

The British psychologist Jeffrey Alan Gray (1934-2004) presented in 1970 his factorial-biological theory on the structure and bases of interindividual differences in personality; according to the model, these are due to biological mechanisms that are related to reactions to reinforcement, punishment or to new stimuli and situations.

In this regard, Gray described two main biological mechanisms that determine behavioral trends. He called one of them “mechanism of behavioral approximation” and the other “mechanism of behavioral inhibition”; these would be equivalent to the basic factors of personality, which would have a physiological basis.

Gray’s theory of personality is largely based on Eysenck’s PEN model , which defines three major biologically determined personality factors: neuroticism, extraversion, and psychoticism. However, there are significant differences between both theories that are worth commenting on; we will dwell on them later.

Thus, Gray proposes two basic dimensions of personality: anxiety and impulsivity . The first combines the introversion and neuroticism of Eysenck’s model; in contrast, a high level of impulsivity would also imply a high level of neuroticism, but in this case it would be associated with extraversion. Each dimension corresponds to a behavioral mechanism.

Anxiety and the mechanism of behavioral inhibition

According to Gray’s description, anxiety is a combination of neuroticism (or emotional instability) and introversion. In Eysenck’s model, extraversion is characterized by personality traits such as activity, dominance, assertiveness, sociability, and sensation-seeking, and introversion would be its opposite.

The mechanism of behavioural inhibition, which is associated with this primary dimension of the personality, is mainly involved in the avoidance of unpleasant situations and stimuli , i.e. punishment. Given that it is determined by biological variables, the mechanism would be activated to a different degree in each person.

Among the main functions of the behavioural inhibition mechanism, and therefore of anxiety, we can highlight the response to punishment, the inhibition of obtaining reinforcers in certain circumstances (e.g. delaying reinforcement) and the avoidance of new and potentially aversive stimuli.

Having a high level of anxiety predisposes the person to frequently experience frustration, fear, sadness and other unpleasant feelings . Therefore, this trait is associated with behavioral avoidance of stimuli that are perceived as anxious by the individual.

Impulsivity and the mechanism of behavioural approximation

The Impulsivity factor in Gray’s model combines high levels in Eysenck’s Neuroticism and Extraversion dimensions. In this case the relevant biological system would be the mechanism of behavioural approximation, which when activated would make us behave in the opposite way to the mechanism of inhibition.

Thus, in this case the obtaining of rewards is more important than the avoidance of punishments . This behavioural system favours the approach to new stimuli and situations and is activated mainly by the possibility of obtaining reinforcement, unlike the behavioural inhibition mechanism, which depends on punishment.

According to Gray, people with a high level of activity of the behavioral approach mechanism (or impulsive, if you want to put it that way) tend to show positive emotions like joy more often. It could be related to the action of the neurotransmitter dopamine , involved in the brain’s reinforcement system and in motivation.

Similarities and differences with Eysenck’s theory

The personality theories of Eysenck and Gray have obvious similarities; after all, the second author relied mostly on the work of the first when developing his own model. Both are categorized into two major paradigms of personality study: factorial and biological theories.

A key difference between Gray’s and Eysenck’s personality theory is that the former gives greater importance to physiological responses to different types of stimuli, whereas the PEN model is based mainly on classical conditioning , on levels of brain activation and on the functioning of neurotransmitters.

In any case, these are two complementary theories: since Gray started from Eysenck’s model, their factors can be added to those described by this author. Each of them explains different aspects of personality, and the traits they describe could be explained by different but interrelated biological variables .

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Bibliographic references:

  • Gray, J. A. (1970). The psychophysiological basis of introversion-extraversion. Behaviour Research and Therapy, 8(3): 249-266.
  • Gray, J. A. (1981). A critique of Eysenck’s theory of personality. In H. J. Eysenck (Ed.), “A model for personality”: 246-276.