Eysenck vs. Gray: A Comparative Analysis of Personality Theories

The essay discusses how Eysenck's and Gray's theories provide frameworks for understanding individual differences in personality through brain functioning. Eysenck proposed a model centered on two dimensions: Extraversion-Introversion and Stability-Instability, emphasizing biological underpinnings and linking arousal levels to these traits. In contrast, Gray’s Reinforcement Sensitivity Theory (RST) focuses on the behavioral approach system (BAS) and behavioral inhibition system (BIS), attributing personality differences to variations in sensitivity to rewards and punishments. While Eysenck's model is supported by genetic studies highlighting heritability of traits like intelligence, Gray's theory finds backing from research on anxiety and depression. Despite their different emphases—Eysenck on arousal and neuroticism, Gray on motivation systems—the theories converge on the idea that personality can be linked to specific brain processes. Ultimately, Eysenck’s broader use of physiological constructs provides a more generalizable link between personality traits and behavior compared to Gray's more focused neuropsychological approach.

Running Head: PSYCHOLOGY
Psychology
Name of the Student
Name of the University
Author Note

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The aim of the essay is to discuss with evidence how do the Eysenck and the Gray
theories of 'E' and 'N' agree, and how do they differ? The essay discusses if either model is
well discussed with evidence. Eysenck and the Gray theories hypothesised that personality
traits aid in understanding the differences in brain functioning in an individual. Both the
theories assumed that the brain process can be characterised by the means of a simplified
conceptual nervous system, which contains circuits of personality and behaviour (Zuckerman,
2014).
Eysenck's Extraversion - Stability model or E model favours only two dimensions,
which are Extraversion – Introversion and the stability – Instability. This theory emphasised
on biological basis of the personality traits. Eysenck's studies found many links between the
Stability - instability and the Extraversion – Introversion and were associated with differences
in the pattern of arousal in brain of an individual. The studies concluded that extrovert people
had low level of arousal in brain and they engage in high level of social contact for achieving
an optimal level of cortical arousal. On the contrary, the introvert people have high level of
arousal within brain (Claridge, 2016).
The studies of Gray agreed on the differences in arousal levels linked with stability
and instability. Gray highlighted that people with stable nervous system/Neuroticism-stability
or “N” have less significant or a gradual shift in the arousal and vice versa in unstable people.
Gray developed the Reinforcement sensitivity theory based on biological analysis at starting
point. On the other hand, Eysenck's studies established the theory and later made the
connections to the biological aspect on this note both the theories differ (Hundt et al., 2013).
According to Gray the different personality of human beings is due to variations of internal
factors of rewards and punishments. This inner biological system has variations of sensitivity
that gives rise to differences in personality. Gray’s theory emerged as alternative to the
Eysenck's studies (Jappe et al., 2011).

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According to Gray, an individual difference in personality arises during cultivation of
new skills at a young age. It is because while learning new skills a person encounters the
reward or punishment. In this behavioural approach system (BAS), a person at young age
learning a new behaviour is more sensitive to rewards and in behavioural inhibition system
(BIS) a person demonstrates a greater sensitivity to punishment. In this aspect it can be said
that the behavioural approach and sensitivity system align or are linked with the personality
map developed by Eysenck. Therefore, both theories agree on this note as per Hundt et al.
(2013).
Eysenck’s model was discussed with the evidence from the genetic studies on twins
which revealed that variation in the behavioural patterns by 25% in twins is due to genetic
factors. In some genetic studies with monozygotic and dizygotic twins who were born and
bought up at different regions, the psychological assessment revealed that the intelligence
was strongly influenced by twins. Based on this evidence Eysenck concluded that
“heritability of intelligence” was approximately 70% of the whole population. The views of
Eysenck matched with further genetic studies. The theories of Gray originated from study on
biology of personal traits, motivations and contradict Eysenck’s view on explaining
personality disorder based on classical conditioning alone. This model is explained with
evidence from studies conducted on people with anxiety and depression that showed high
BIS sensitivity (Heym et al., 2008).
Overall both the theories differ in the use of level of physiological construct. Gray
used arousal in restricted manner when compared to Eysenck’s model. Eysenck's reticulo-
cortical and limbic systems may be compromised of number of pathways and structures. In
his studies the ascending reticular activating system (area of brain associated with arousal)is
broadly defined. On the other hand the BIS and BAS system of Gray are found as separate
from the arousal despite these systems are in dynamic interaction. It emphasised mainly on

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the Anxiety, Impulsivity, approach motivation, and avoidance motivation unlike Eysenck’s
emphasis on Neuroticism, Extraversion, and arousal (Zuckerman & Glicksohn, 2016).
Based on the above discussion it can be more convincing to agree with the
Eysenck's theory as arousal used by him as mediating variable and is useful to link the
personality to different response indices. On the other hand Gray's more neurologically
detailed theory is silent and is applicable to predict the narrower range of behaviours and for
one-grained neuropsychological description.

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References
Claridge, G. (2016). Hans Eysenck's contribution to our understanding of personality and
psychological disorders: A personal view. Personality and Individual
Differences, 103, 93-98.
Heym, N., Ferguson, E., & Lawrence, C. (2008). An evaluation of the relationship between
Gray’s revised RST and Eysenck’s PEN: Distinguishing BIS and FFFS in Carver and
White’s BIS/BAS scales. Personality and Individual Differences, 45(8), 709-715.
Hundt, N. E., Brown, L. H., Kimbrel, N. A., Walsh, M. A., Nelson-Gray, R., & Kwapil, T. R.
(2013). Reinforcement sensitivity theory predicts positive and negative affect in daily
life. Personality and Individual Differences, 54(3), 350-354.
Jappe, L. M., Frank, G. K., Shott, M. E., Rollin, M. D., Pryor, T., Hagman, J. O., ... & Davis,
E. (2011). Heightened sensitivity to reward and punishment in anorexia
nervosa. International Journal of Eating Disorders, 44(4), 317-324.
Zuckerman, M. (2014). Sensation seeking (psychology revivals): beyond the optimal level of
arousal. Psychology Press.
Zuckerman, M., & Glicksohn, J. (2016). Hans Eysenck's personality model and the constructs
of sensation seeking and impulsivity. Personality and Individual Differences, 103, 48-
52.