Experimental Psychiatry. V — Psilocybine, a New Psychotogenic Drug

This open-label study (n=4; 1960) with psilocybin (5-10mg) describes the subjective effects of the participants. The effects found range from slower speech to trying to stay in control (overcontrol). The participants didn’t experience hallucinations and only one participants’ pupils dilated.


From the first paragraph: “Psilocybine, the phosphoric ester of 4-hydroxytryptamine has been established by [Albert] Hofmann et al. as the active principle of the Mexican mushroom family Psilocybe mexicana Heim. The chemists emphasize the fact that this chemical is the only phosphorylated indole compound that is known to occur in nature and that it is remarkable in that it is an indole substituted at the fourth position.”

Authors: Max Rinkel, Charles R. Atwell, Albert DiMascio & Jonathan Brown


Thie paper starts with summarizing what was known in 1960 about psilocybin.

The first note made is about the effects on animals, from slowing down movement to the dilatation of pupils. The authors also note the low toxicity, and that up to 200 mg per kg had been administrated in mice without lethal effect.

Two earlier reports on the mental effects of psychedelics are shortly discussed.

The current study was conducted with four volunteers who received between 5 to 10mg psilocybin. The study only observed mental and behavioral changes, there was no active intervention besides some psychological tests.

This is what the study found:

  • Hallucinations: none found, one participant did report illusions
  • Mood: both positive and negative, with overcontrol (trying to stay in/exert control) observed
  • Behavior: two participants become more active, the other two became sleepy
  • Speech: quicker and slower
  • Thinking: no distortions, so logical but slower
  • Somatic Symptoms: pupils dilated in one participant, nausea and slight discomforts reported
  • Psychological Tests: lower scores than in earlier LSD experiments

The discussion ends with a list of factors that can influence the effects of psychedelics. They included the influence of the researcher, where the experiment takes place (setting), the dosage and route of administration (substance), the expectancy and mood of the participants (set), and interestingly a note on the purity of the drug. It is, we believe now falsified, stated that the impurity in the plants (or fungi) of psychedelics may be responsible for their dramatic effects in other settings.