What is a psychedelic experience?

What does “psychedelic” mean?

“Psychedelic” means mind-manifesting. The psychiatrist Humphry Osmond introduced the word in 1957, at a meeting of the New York Academy of Sciences, building it from the Greek psyche, mind or soul, and deloun, to show. The drugs it described were then usually called psychotomimetic, “psychosis-mimicking”, a name that treated their effects as a model of madness. Osmond wanted a word that was, as he put it, “clear, euphonious and uncontaminated by other associations”.¹

The new word pointed attention somewhere else. A psychotomimetic state is interesting for how far it departs from normal functioning; a psychedelic one is interesting for what it shows of the mind. CPS founder Aidan Lyon develops this idea in Psychedelic Experience: Revealing the Mind (Oxford University Press, 2023), which reads “psychedelic” as mind-revealing: an experience is psychedelic when aspects of the mind that are normally hidden are revealed to consciousness. The word then names a kind of experience, and the drugs that carry its name become one way among several of producing it.² This is the sense in which The Center for Psychedelic Space uses the word.

What happens during a psychedelic experience?

It varies a great deal between people and between occasions, but some changes are reported again and again. Perception often becomes unusually vivid. Colours seem saturated, patterns or whole scenes appear when the eyes are closed, and the senses can blend, so that music is seen as well as heard. Emotions are often amplified and can shift quickly, from bliss or tenderness to anxiety or grief. Ordinary objects can seem charged with significance, and many people come away feeling they have understood something about themselves or the world.

The deeper changes concern things that usually go unnoticed because they hardly ever vary. The body can come to feel distant or unfamiliar. Time can stretch, so that minutes feel like hours, or seem to stop. The boundary between self and world can soften. At the far end, what changes is the organisation of experience itself: the usual arrangement of a perceiving self, here, facing a world, out there, can loosen or come apart.

None of these changes, on its own, makes an experience psychedelic. They describe some of the territory that psychedelic experiences can move through, and that territory has recurring features. The Altered States of Consciousness rating scale (in versions known as the OAV and the 5D-ASC), one of the most widely used questionnaires, was designed to compare altered states whatever brought them about. Pooling 43 experiments, researchers found that its scales, for features such as unity, disembodiment and complex imagery, measured consistently across different drugs and settings.³

Are some experiences more psychedelic than others?

Yes. On the account developed in Psychedelic Experience, an experience can be psychedelic to a greater or lesser degree, and in different ways.² A vivid hallucination may be extraordinary without revealing very much about how the mind works. Noticing, with unusual clarity, how an emotion arises, how attention moves from one thing to the next, or how the familiar sense of self is put together can be highly revealing and still look like very little from the outside.

To compare experiences by what they reveal, the book proposes psychedelic space: four dimensions along which an experience can be more or less mind-revealing.²

• Scope: how much of the mind it reveals.
• Clarity: how clearly, and how accurately, it reveals it.
• Novelty: how new to the person the revealed aspects are.
• Duration: how long the revealing lasts.

Any psychedelic experience can be placed somewhere in this space, and in general, the further out it lies along these dimensions, the more psychedelic it is. On this view, “psychedelic” is a matter of degree and of structure, and whatever happens after someone takes a psychedelic drug does not automatically qualify. Clarity deserves particular attention, because an experience can reveal the mind accurately in one respect and distort it in another. The book calls the opposite tendency psychecryptic, or mind-concealing: experiences that obscure or misrepresent the mind. An experience can be strange, intense and drug-induced, and still conceal more than it reveals.²

Why do people talk about “ego death”?

“Ego death” is the popular name for an experience in which the ordinary sense of being a separate self fades or seems to vanish. Researchers usually call it ego dissolution, which is more accurate: it describes a temporary change in how the self is experienced, and nobody’s personality comes to an end.

Ego dissolution is closely tied to psychedelic drugs in particular. On a short questionnaire built to measure it, the Ego-Dissolution Inventory, scores rose with the dose of psychedelics but not of cocaine or alcohol, and went together with a sense of unity with one’s surroundings.⁴

Losing the sense of self can mean several different things. A review comparing psychedelics and meditation distinguishes the narrative self, built from autobiographical memory and thoughts about oneself, from the embodied self, rooted in bodily sensation and the sense of being located somewhere in space. Psychedelics and meditation may affect these differently. The authors also caution against confusing a temporary state of reduced selfhood with selflessness as a lasting trait of character, while noting preliminary evidence that the two may be connected.⁵

What is a mystical experience?

In research, a mystical-type experience is one marked by a sense of unity with everything, of sacredness, of deep peace or joy, of being outside ordinary time and space, and of being unable to put the experience into words. For the question of what such experiences reveal, the most important feature is what researchers call their noetic quality: the conviction of having encountered something real, often more real than everyday life.

Reports of this kind go back centuries, across many religious traditions. They have occurred in the course of contemplative practice and also to people who were not seeking them. Researchers now measure them with the Mystical Experience Questionnaire (MEQ30). In controlled laboratory studies, psilocybin given under supportive conditions has occasioned what this questionnaire counts as a complete mystical experience in the majority of people studied.⁶

Measuring an experience does not settle what it means. A questionnaire can establish that someone had an experience with these characteristics, including the felt certainty of having learned something true. It cannot establish whether what seemed to be revealed was in fact true. A sense of encountering ultimate reality might be an insight, an illusion, or something that fits neither word comfortably. This is where the clarity dimension of psychedelic space matters, since an experience can feel completely revealing and still be inaccurate about what it seems to show. CPS keeps that question open, neither dismissing such experiences nor deferring to them.

Can you have a psychedelic experience without drugs?

Yes, at least if the word “psychedelic” is taken seriously. If what makes an experience psychedelic is what it reveals, psychedelic drugs are methods for producing such experiences, and they do not define the category. Psychedelic Experience argues that meditation, in particular, can produce psychedelic experiences in this full sense.²

Meditation is the clearest comparison. A review of the two fields describes meditation as a set of techniques for monitoring and regulating attention, perception, emotion and bodily processes such as breathing, and notes that many contemplative traditions explicitly aim to dissolve the sense of self. Both meditation and psychedelics can disrupt the experience of self and the brain processes beneath it. The review also stresses that neither forms a single, uniform category, and that experiences described in similar words can differ in important ways.⁵ In the brain, researchers have drawn parallels between psychedelics and some meditative practices in the default mode network, a set of regions associated with self-related thought.⁶

What remains open is empirical. Where do experiences reached by these different methods overlap, where do they diverge, and what can the pattern teach us about the mind? Some experiences need no method at all: mystical experiences, for example, have been reported by people who were not looking for them.⁶

Why do set and setting matter?

A psychedelic drug does not determine a single experience. It changes the conditions under which experience is generated, and what follows depends a great deal on the person and the circumstances. “Set” is the mindset a person brings: expectations, intentions, mood and history. “Setting” is the physical and social environment.

Research on set and setting counts expectancy, preparation and belief among the non-biological factors that shape how people respond to a drug.⁷ In the terms used above, the same substance, taken by different people in different circumstances, can lead to very different regions of psychedelic space. Researchers have long designed for this. Walter Pahnke’s Good Friday experiment, published in 1963, held its sessions in a chapel during a Good Friday service to make the most of set and setting.⁶ Setting also bears on safety: in a survey of difficult psilocybin experiences, risky behaviour was more likely when people lacked physical comfort and social support.¹⁰

Why can psychedelic experiences be difficult?

Psychedelic experiences can become frightening or overwhelming. People describe intense fear, grief, paranoia, a sense of dying or of going insane, feeling profoundly alone, and physical distress. The Challenging Experience Questionnaire, developed to study these “bad trips”, groups them into seven kinds along those lines.⁹

A difficult experience is not necessarily a harmful one, but the risks are real. In a survey of 1,993 people describing their single most difficult experience with psilocybin mushrooms, 39% ranked it among the five most challenging experiences of their lives, and 84% said they had benefited from it. Eleven per cent had put themselves or others at risk of physical harm, and 7.6% of those whose experience was more than a year earlier had sought treatment for lasting psychological symptoms.¹⁰

These figures come from people using mushrooms outside research settings. In laboratory studies with screened, prepared and supported participants, the same authors report, risky behaviour and lasting distress are extremely rare.¹⁰ The contrast is one reason why safety guidelines for clinical research recommend screening, careful preparation, a safe physical environment and support from people the participant has come to trust.⁸ Afterwards, many people find it useful to work through what happened instead of setting it aside, a process usually called integration.

This page is information, not medical or legal advice, and the legal status of psychedelic substances varies from place to place. If you or someone with you is in crisis or at risk of harm, please contact your local emergency services.

How does CPS study psychedelic experience?

It starts with the experience. Psychedelic drugs, meditation and other methods are ways of changing consciousness, and CPS does not let the method decide in advance how the resulting experience should be classified.

Psychedelic Experience developed psychedelic space as a general framework for comparing mind-revealing experiences according to what they reveal and how they reveal it.² More recent CPS research asks a different but related question: whether contemplative traditions, such as the yogic map of the chakras, identified recurring structures and transformations within this wider territory that can be tested scientifically. The work compares first-person reports with psychometrics, behavioural measures and neuroimaging. The results so far are suggestive rather than conclusive, and the research page sets out what each finding does and doesn’t show.

The same epistemic attitude guides CPS’s practical work in psychedelic coaching: take unusual experiences seriously, understand them carefully, and avoid becoming certain too quickly about what they mean. CPS offers coaching and education, not therapy, and it does not provide substances. A separate guide explains how a psychedelic coach differs from a therapist or facilitator, and the questions page answers what people ask before booking.