Experimental Psychiatry. V - Psilocybine, a New Psychotogenic Drug
Atwell, C. R., Brown, J., DiMascio, A., Rinkel. M.
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.
Abstract
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.