Hans Eysenck offered a theory of personality that emphasized the importance of heredity and genetics in forming our ability to learn and adapt to the environment. Contrary to Cattell, who identified sixteen primary personality factors, Eysenck narrowed these down to three, focusing more on higher-order factor analysis. These are extraversion/introversion, neuroticism/stability, and psychoticism/superego. Each of this aspects of personality can be tracked to a different biological cause. Thus in this theory, personality is dependent on the balance between the excitation and inhibition process of the autonomic nervous system.
In extraversion/introversion, extroverts inherit an under-aroused nervous system; hence they seek stimulation. This is made through being sociable, carefree, optimistic, and impulsive. Conversely, introverts are reserved and can control their actions and emotions, serious and pessimistic because they are already over-aroused and stimulated.
In neuroticism/stability, the level of neuroticism is observed through the reactivity of the personβs sympathetic nervous system. Stable people have a less reactive, calm, and composed character. Their nervous system is observed to be stable amidst stressful situations. On the flip side, neurotic peopleβs nervous system is unstable and responds quickly to stress. They are prone to overreacting, anger, and fear.
Lastly is psychoticism/normality. Psychoticism is the lack of empathy, often times cruel, a loner, and troublesome. This is due to high levels of testosterone. On the opposite, Β lower testosterone levels result in a more balanced and normal behavior.
