On Good Friday, 1962, before services commenced in Boston University's Marsh Chapel, Walter Pahnke administered small capsules to twenty Protestant divinity students. Thus began the most scientific experiment in the literature designed to investigate the potential of psychedelic drugs to facilitate mystical experience. Half the capsules contained psilocybin (30mg), an extract of psychoactive mushrooms, and the other half contained a placebo. According to Pahnke, the experiment determined that "the persons who received psilocybin experienced to a greater extent than did the controls the phenomena described by our typology of mysticism.Accordingly, the experiment was designed to administer psilocybin to a previously acquainted group of Christian divinity students in church during a Good Friday service. Pahnke designed the questionnaire he used to measure the occurrence of a mystical experience specifically for the experiment. No similar questionnaires existed at the time. Pahnke decided to measure the mystical experience in reference to eight distinct experiential categories. The categories include 1) sense of unity, 2) transcendence of time and space, 3) sense of sacredness, 4) sense of objective reality, 5) deeply felt positive mood, 6) ineffability, 7) paradoxically and 8) transiency.In Pahnke's original questionnaire and in the subsequent revisions, the completeness with which each subject experienced each category is measured through numerical responses to category- specific questions. The questions themselves are of two types. The predominant type asks the subject about experiences of a new perspective. These type of questions are sufficiently detailed and specific to be an effective test for the specific category. The second type of question, used much less frequently, asks about the loss of a normal state.
Both the six-month and long-term follow-up questionnaire results support Pahnke's hypothesis that psilocybin, when taken in a religious setting by people who are religiously inclined, can facilitate experiences of varying degrees of depth that either are identical with, or indistinguishable from, those reported in the cross-cultural mystical literature. In addition, both the six-month and the long-term follow-up questionnaire results support Pahnke's hypothesis that the subjects who received psilocybin, more so than the controls, experienced substantial positive persisting effects in attitude and behavior.In contemporary psychotherapy research, more sophisticated methods than Pahnke's are used to assess personality change. Reports from significant others such as family members and close friends of the subject are almost always used to add an important "objective" element in assessing personality change. Data from the follow-up questionnaires, administered by Pahnke at six-months and by the author after twenty-four to twenty-seven years, should be considered valuable as far as they go, but this is not very far. Since no detailed personality tests were given prior to the experiment, results of such tests at the time of the long-term follow-up would have been of little value and were not conducted. The long-term follow-up interviews, because of their open-ended format and extensive questioning, yielded more detailed information than the questionnaire about the content of the experiences and the persisting effects.
The original Good Friday experiment is one of the preeminent psychedelic experiments in the scientific literature. Despite the methodological shortcomings of the unavoidable failure of the double-blind and the use of several imprecise questions in the questionnaire used to quantify mystical experiences, the experiment's fascinating and provocative conclusions strongly support the hypothesis that psychedelic drugs can help facilitate mystical experiences when used by religiously inclined people in a religious setting. The original experiment also supports the hypothesis that those psilocybin subjects who experienced a full or a partial mystical experience would, after six months, report a substantial amount of positive, and virtually no negative, persisting changes in attitude and behavior.The team should include psychiatrists, psychologists and religious professionals from a variety of traditions, as well as drug abuse prevention, education and treatment officials. Questions as fundamental as those raised by the Good Friday experiment deserve to be addressed by the scientific community, and pose special challenges to the regulatory agencies. Renewed research can be expected to require patience, courage and wisdom from all concerned.