Drugs and Personality

In the previous paper we have given a brief discussion of the reasons why figural after-effects are of interest in the study of personality and why stimulant and depressant drugs would be expected to have certain effects upon them (Eysenck and Easterbrook, 1960a). In this paper we describe an experiment using kinaesthetic figural after-effects rather than visual ones. By and large results with kinaesthetic figural after-effects have been more clear-cut and definite in relating these after-effects to personality; several studies have shown extraverts to have greater figural after-effects than introverts (Eysenck, 1957). Furthermore there is at least one study demonstrating that stimulant and depressant drugs have the predicted results upon kinaesthetic figural aftereffects (Poser, 1958). The reasons for this may be that whereas for visual experiments it is difficult to check on the subject's ability to maintain fixation, nothing comparable is required in experiments on kinaesthetic figural aftereffects. Furthermore any departure from instruction on the part of the subject can easily be checked by the experimenter. For these reasons kinaesthetic tests have very definite advantages over visual ones.