The Eysenck Personality Questionnaire (EPQ) is a measure that assesses individual personality traits that was developed by Hans and Sybil Eysenck. Hans Eysenck was a German psychologist who theorized that personality traits develop from innate genetic influences that are biological and inherited. Eysenck’s main focus was on temperament which he saw as long term patterns of behavior.
He originally identified two areas of temperament: neuroticism and extroversion/introversion. Neuroticism is a temperament level that ranges from calm to nervous. The extroversion and introversion area of temperament is a range between shyness and an outgoing nature. On this spectrum individuals vary widely. Later on, Eysenck added a third area of psychoticism to incorporate people with mental illness. The EPQ contains 100 yes/no questions on the normal version with a short scale that contains 48 questions.