Drugs and Personality

Abstract

In a previous paper in this series Eysenck, Holland and Trouton (1957) showed that the seen after-effects resulting from stimulation by means of a rotating spiral were increased very little by a stimulant drug and decreased significantly by a depressant drug. At that time there was little evidence that these aftereffects were in fact correlated, as the theory demanded, with extraversion and introversion. Since then two separate experiments dealing with normal and neurotic subjects respectively produced very strong evidence in favour of this hypothesis (Eysenck, 1960), and it seemed desirable to repeat the experiment in order to discover whether the failure of the stimulant drug in the first experiment to produce very positive results was merely a chance effect or was in fact a genuine failure of the theory.