Study Participants Experience Psychedelic Effects after Receiving Placebo

A study from McGill University shows that the power of the mind alone can produce a quasi-psychedelic experience.


The mind can be a powerful healing tool when given a chance. The notion that your brain can convince your body a bogus remedy is the real thing — the placebo effect — and thus induce healing has been around for millennia.

In modern times the first to describe the placebo effect was T.C Graves, in the medical journal The Lancet, in 1920.1 He spoke of “the placebo effects of drugs” being demonstrated in those cases where “a real psychotherapeutic effect appears to have been produced.”

A hotly debated topic in modern medicine is the apparent placebo effect observed in conventional antidepressant treatment, with some claiming that anywhere from 30-45% of the response is all in the mind.2

Conversely, researchers find it challenging to replicate placebo conditions in the recent revival in research into psychedelic therapies for neuropsychiatric disorders. By definition, psychedelics produce pronounced subjective effects in individuals (the term psychedelic comes from the Greek for “mind-manifesting”), such as hallucinations, changes in perception, etc.3 These effects make it difficult to adequately blind experiments as participants quickly determine whether they ingested a placebo due to the absence of psychedelic effects.

However, a recent study conducted at McGill University in Montreal sheds new light on the concept of a “psychedelic placebo.” 4

Smoke and Mirrors: The Power of Suggestion

This study demonstrates a masterclass in the art of deception. The group recruited participants under the pretense that they would be taking a small dose of the psychedelic drug iprocin — a homolog of psilocybin, the prodrug of psilocin in psychedelic mushrooms. Iprocin is an obscure psychedelic, so the researchers could better control participants’ expectations. Some of the purported effects included:

Improved mood, heightened cognition, emotional sensitivity, light sensitivity, hallucinations, sleepiness, tingling sensation of the skin, vivid recall of memories, increased perspiration, slurred speech, mild anxiety, slower reflex response, and dizziness.

Researchers claimed that the study aimed to examine the “effect of a psychoactive drug on creativity.” They recruited thirty-three participants. The experiment ran in two separate sessions. For the initial sample, experimenters attempted to exclude people with prior psychedelic drug use. But later, many revealed that they had hidden their earlier experience for fear of being excluded from the study. Thus, in the second sample, the researchers removed this rule from the screening.

The group used an elaborate scheme to conceal the fact that they were investigating placebos. They went to great lengths to plant the expectation that there was no placebo control group. The researchers dressed in white lab coats, equipped with a clipboard in hand, asked participants to present government-issued photo identification, making the procedure appear more official.

Setting the Scene

The experiment took place in a room that had a naturalistic ambiance resembling a party. Psychedelic artwork with visual illusions decorated the walls. Participants could paint and watch visually stunning documentaries that were projected onto the wall (Figure 1).

Figure 1: Experiment room4

As the participants entered the room, the experimenter told them to sit in a semi-circle arranged by participant number. At the point, the deception escalated. As a part of the study, the research group recruited confederates – participants that were in on the experiment – to act like they were tripping. The confederates distributed across the room and engaged with the unknowing participants.

At the onset of the experiment, participants completed three questionnaires measuring personality, mood, and subjective experience. To influence participants beliefs that everyone was receiving the same drug (i.e., that there was no separate control group), researchers encouraged the study group to select any pill cup from the tray, implying that they were all identical

Approximately 15 minutes after ingestion, the confederates started to act out the effects of the drug in subtle ways. These undercover operatives were directed to mirror and then exaggerate the behaviors displayed by other participants. For example, if participants appeared to show an elevation in mood, the confederates would match this increase, acting even happier. To give the impression that 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?”

Following 45 minutes of mingling, the participants completed the same mood and experience questionnaires like the ones completed before they ingested the placebo. At 3.5 hours into the study, the participants regrouped for a debriefing and were told the true nature of the experiment.


There was substantial individual variation in placebo effects.  Participants reported changes in experience greater than those associated with moderate or high doses of psilocybin.  The majority of the participants (61%) described feeling some effect after ingesting the “drug.”

One study subject reported feeling nauseated throughout the study. She felt hot with sweaty palms and reported that her arms and legs felt heavier. Another mentioned she was “very surprised it was a placebo” and that she “definitely felt [she] was high on something.” She reported heightened senses, with sounds and colors being more vibrant.

One other participant also reported perceptual changes and was documented as saying, “I had not been feeling anything until looking at this [painting]. It’s moving. The colors aren’t just changing; it’s moving. It’s reshaping itself.”

Among experienced psychedelic users, 50% verbally reported effects, while this figure was 70% for naive psychedelic participants.

Thirty-nine percent of those who took part in the trial reported feeling nothing out of the ordinary.

Putting it in Context

The findings from this study outline the importance of two important concepts relating to the psychedelic experience; set and setting, and contact highs. Set refers to one’s mindset – prior to and during a psychedelic experience. The outcomes of a psychedelic session vary greatly depending on how the individual prepares for and interprets the experience – i.e., if one enters the experience for recreation, learning purposes, or as a therapy.

The setting is the physical environment in which the psychedelic experience takes place. The experimenters in the study primed the participants’ mindset and created a setting conducive to a psychedelic experience.

The second concept, a contact high, refers to a situation in which individuals experience drug-like effects without ingesting a drug but just by being around others who have. In the study mentioned above, having confederates act out the effects of the drug may have promoted what the authors label a “placebo contact high.”

Overall, the study highlights the significance of the placebo element of psychedelic drugs. Understanding the psychedelic experience means distinguishing which parts are due to the drug itself and which are due to the contextual factors.5 The results of the study aids in shifting the view of placebo effects from an unwanted outcome to a display of the power of context in both modulating and producing the psychedelic experience.


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Rick Strassman
4 years ago

Add a psychedelic, and the placebo effect becomes even greater.

4 years ago

Pretty useless study without a control group.