Hans Eysenck's Model of Individual Differences

Hans Eysenck may be a somewhat controversial figure in the world of psychology, but no one doubts the value of his scientific approach to psychological research.

Written and verified by the psychologist Gema Sánchez Cuevas.

Last update: 02 February, 2024

Hans Eysenck is one of the most respected names in the history of psychology. Many people credit him for bringing psychology into the scientific world. As a result, he’s often referred to as “the father of psychology”.

Hans Eysenck was born in Berlin, Germany in 1916. When Hitler rose to power, Eysenck decided not to join the National Socialist German Workers’ Party (the Nazi Party), so he fled to England. There, he studied psychology at the University of Exeter. Later, he worked at Mill Hill Emergency Hospital of London, where he provided psychiatric treatment to military personnel. 

Eysenck later became a professor at University College London, where he started formulating his theory. Classic behaviorists such as Ivan Pavlov and John Watson inspired Eysenck’s work. Eysenck’s theory highlights the genetic and physiological factors of personality. He was also very interested in how to measure behavior.

The origins of Hans Eysenck’s theory

Many people believe that Hans Eysenck’s theory is more closely related to the study of temperament than personality. Nevertheless, it became known as a personality theory. Interestingly, Eysenck initially based it on Galen’s four temperaments: sanguine, choleric, melancholic, and phlegmatic.

Basically, Hans Eysenck proposed that each human being has certain characteristics that stay stable over time. The configuration of each person’s nervous system is a determining factor. Each individual has a nervous system with a unique genetic and physiological makeup. Consequently, each individual is different.

Hans Eysenck also took sociocultural influences on personality into account. Nevertheless, he always believed that biological factors were more relevant to personality differences. One thing that distinguished him from other psychologists was his interest in having an empirical basis for his theory. Consequently, he ran a series of experiments to test his theory. These tests contributed a lot to psychometrics.

The three primary dimensions

Eysenck claimed that there are three primary dimensions of personality that are determined by heritage and manifest themselves physiologically. He believed you could measure them by observing the reaction of the autonomous nervous system. Then, Eysenck defined the three basic dimensions of personality and their structure and traits.

These three dimensions are:

• Extraversion-Introversion: Traits such as vitality, impulsiveness, sociability, dynamism, dominance, dogmatism, and exploration correspond to this dimension.
• Neuroticism: This dimension includes traits such as shyness, irrationality, emotiveness, low self-esteem, anxiety, guilt, and instability.
• Psychoticism: Traits such as aggressivity, coldness, cruelty, egocentrism, and difficulty feeling empathy fall into this category.

For Hans Eysenck, the development of these traits depends on the excitation or inhibition of the cortex. In other words, basic personality traits are determined by biological factors.

The transcendence of Eysenck’s theory

Hans Eysenck’s radical behavioralist posture makes him a controversial author. Nevertheless, no one dares to question his theory’s validity. His experiments were impeccable, so everything he proposed has an empirical foundation. What’s more, his personality measurement systems are still used and recognized all over the world.

Eysenck was a tough critic of the popular therapies of his time. In general, he believed the psychodynamic and psychoanalytic focus was basically ineffective. As a result, he dedicated his life to creating a theory that would translate into measurable and effective therapeutic interventions. His main contribution was that he provided an empirical basis for behavior-based therapy.

Some of Eysenck’s most famous works are The Biological Basis of Personality (1967), Sex and Personality (1976), and Intelligence: The Battle for the Mind (1981). He also designed numerous questionnaires and tests to evaluate personality traits. The most famous one is the Eysenck Personality Inventory. Eysenck died of a brain tumor in London in 1997, but his legacy lives on.