This book is a carefully documented presentation of the relationship between pre-existing personality types and the altered states of consciousness induced by the administration of LSD.

A group of male actors varying considerably in intelligence, socioeconomic background, and personality patterns was selected for the experimental study. All subjects were carefully screened to eliminate gross psychoses and were studied by means of personal interviews, a detailed questionnaire, and a wide battery of psychometric tests including projective studies, human figure drawings, etc. Then, LSD was administered to one group of subjects, and a placebo to a control group.

The psychological data were carefully assessed and categorized into six LSD reaction types. Formal characteristics of the manner of thinking, the content and form of ideation, affective changes, modalities related to perception and nature of experiencing, controls,