More than half of the participants in a study exploring the placebo effect said that they hallucinated on fake psychedelic drugs, according to researchers from McGill University in Quebec. Results of the study, which was led by a psychiatry Ph.D. candidate who is also a former magician, were published recently in the journal Psychopharmacology.

To conduct the study, researchers staged a fake party in a room that included elements such as ambient music, video projections, cushions, and snacks. The 33 test subjects were told that the experiment was designed to study the effects of a fictional psychedelic drug called iprocin in a natural environment.

“The experimenter explained that iprocin was a fast acting and legal drug similar to psychedelic mushrooms,” the researchers wrote in the study. “Its effects start quickly, within 15 min, peak in 1 to 2 h, then quickly fade. We told participants that they would stay in the room until the effects had worn off, but that these would unlikely persist beyond the 4-h study.”

During the four hours, researchers in white lab coats circulated through the room and took meaningless notes on clipboards. Other researchers, known as confederates, worked undercover, pretending to be participants in the study and reporting strong psychedelic experiences to the actual test group.

“To make it appear as if the drug was having a physiological effect, one confederate with naturally large pupils told some participants individually, ‘Your pupils are huge! Are mine like that?’,” the researchers write. “The room contained no mirrors (nor did the bathroom) or phone cameras for participants to verify this statement, and the dark room with red lights naturally dilated their pupils.”

Tripping On Nothing

After the experiment, the participants were interviewed and asked a variety of questions about their experience during the party. More than 60% reported that they had experienced some kind of psychedelic effect, such as feeling “heavy” or seeing paintings move. When the experiment was run again, researchers specifically asked participants if they believed they were given a placebo or an actual psychedelic drug. Only 35% said that they were sure they had been given a placebo.

Samuel Veissière, a cognitive anthropologist at McGill who was one of the researchers in the study, said that it illustrates how the placebo effect can influence the results of psychedelic research.

“Placebo effects may have been under-estimated in psychedelic studies,” he said. “The current trend towards ‘micro-dosing’ (consuming tiny amounts of psychedelic drugs to improve creativity), for example, may have a strong placebo component due to widespread cultural expectations that frame the response.”

“These results may help explain “contact highs” in which people experience the effects of a drug simply by being around others who have consumed it,” Veissière added.

Jay Olson, the lead author of the study, said that the research also illustrates how set and setting, referred to as context, can affect a psychedelic experience and could have therapeutic value.

“The study reinforces the power of context in psychedelic settings,” Olson said. “With the recent re-emergence of psychedelic therapy for disorders such as depression and anxiety, clinicians may be able to leverage these contextual factors to obtain similar therapeutic experiences from lower doses, which would further improve the safety of the drugs.”

The study’s authors recommended that future research into psychedelics should include information on the experiences of the members of placebo control groups and that the setting and actions of clinicians and experimenters be described.

“In particular, it would be helpful to describe the list of drug effects given to participants, which can influence their expectations and experiences,” they added.

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