In a 2023 survey of 272 people who had used psychedelics, Alexander Irvine and colleagues collected accounts of how the experience had affected their relationship with nature. One respondent wrote: “I became the forest. First the tree, the branches, the leaves, then I went underground and became the roots, the ground, the living beings in the ground. I was everything.” The essense of the account contains nothing that could be visually reproduced. Instead, it describes a change in how a person experiences themselves in relation to the world.
The usual vocabulary for psychedelic experience is visual. People speak of hallucinations and visions, and the clinical literature catalogs perceptual effects: intensified color, geometric patterns, surfaces that seem to breathe. The assumption underneath is that perception works like a screen and that these compounds change what appears on it.
Psychedelics change perception by changing how a person relates to their surroundings, and the visual effects are the smaller part of that change. Enactive cognitive science treats perception as something an organism does with its environment. On that account, the connection people report during a psychedelic experience is what a loosened boundary between self and world feels like from the inside.
What the Visual Account Leaves Out
The screen picture has solid science behind it. Carhart-Harris and Friston’s REBUS model, short for relaxed beliefs under psychedelics, proposes that these compounds loosen the brain’s high-level expectations, the models it uses to filter incoming information and hold experience in a stable shape. With those expectations relaxed, more information from the senses and the body reaches awareness. The world turns vivid and surprising, and the habitual categories that organize it loosen.
The model explains a great deal of what the acute experience is like. Rigid patterns of thought dissolve, a fixed story of the self becomes hard to maintain, and ordinary things look new.
What it leaves open is why the loosening so often takes the form of connection. Relaxed filters could as easily deliver noise. People instead describe belonging to something larger, a forest that seems aware, a world with more weight and meaning in it. REBUS describes what happens in the brain. What the person meets once the filters loosen is a different question, and an account confined to the skull has no terms for asking it.
Perception as Something an Organism Does
The enactive tradition in cognitive science, developed by Francisco Varela, Evan Thompson, and Eleanor Rosch, starts from a different premise. Perception, then, is an activity. An organism brings forth a meaningful world through its bodily engagement with its surroundings, and the world it perceives depends on how it engages.
The biologist Jakob von Uexküll had given this idea its most durable term decades earlier. Each animal, he argued, lives in an Umwelt, a world made of the signs its body can register and act on. A tick’s world consists of little more than the smell of butyric acid and the warmth of a mammal’s skin. The same oak is a climbing route to a squirrel, a landmark to a bird, and shade to a hiker — one tree, three worlds.
Seen this way, a psychedelic alters the manner of engagement itself, the way an organism and its surroundings meet, and the altered picture follows from that. REBUS fits inside this wider account as a description of the brain’s part in the change. Because what is perceived always depends on how the perceiver is relating, a change in relating changes the perceived world as a whole. The sense of connection is the experience of that reorganization.
What Shifts When Psychedelics Change Perception
Three changes recur in first-person reports, and each concerns relationship more than imagery.
The first is a loosening of the boundary between self and world. Ordinary experience is arranged around a subject looking out at objects. When that arrangement relaxes, people describe merging with their surroundings, or being made of the same processes as the soil and the night sky. The loosening is not always welcome. For a person whose security rests on a firm sense of self it can be terrifying, which is what makes some psychedelic experiences so difficult.
The second is heightened animacy. A person raised in an industrial society learns to read screens, prices, and social cues fluently, and to treat most of the living world as background. The Psygaia Framework proposes that psychedelics widen the human Umwelt for a time, so that more of the environment registers as meaningful. Wind, soil, and the roots of trees move from background to foreground. The themes Irvine and colleagues drew from their survey also include a sense of communication with other species.
The third is insight into interdependence, and it is the least visual of the three. People describe realizations that arrive as felt recognitions: that everything is connected, that actions travel through systems they can suddenly sense. Another respondent in the same survey wrote, “Harming nature would be like hurting myself.”
Whether this way of perceiving is more accurate than the ordinary one is a question the reports cannot settle. What they show is a consistent direction. Interdependence, aliveness, and embeddedness — which habitual cognition keeps in the background — come forward.
Where the Molecules Come From
The compounds themselves have an ecological history. Psilocybin, mescaline, and DMT are made by fungi, cacti, and plants. A 2025 study from Dirk Hoffmeister’s laboratory in Jena found that fiber cap mushrooms of the genus Inocybemake psilocybin with a set of enzymes unrelated to the ones Psilocybe mushrooms use. Evolution arrived at the same molecule twice. What the molecule does for the fungus is still unknown, and the leading idea, that it deters animals that eat mushrooms, remains a hypothesis.
On the human side, these compounds act on a serotonin receptor, and serotonin is a signaling molecule that animals have shared since long before there were mammals. The Psygaia Framework takes this fit seriously and treats psychedelic compounds as signals passing between species. That reading is an interpretation, and the evidence so far neither confirms nor excludes it.
The plainer point stands without it. A psychedelic experience is an encounter between a human nervous system and a molecule made by another organism. What the experience contains comes from that encounter, and the molecule supplies only part of it.
The Setting Is Part of the Experience
This account changes what set and setting mean. The familiar version suggests that context shapes mood and mood shapes the experience. The enactive account goes further. If a psychedelic reorganizes how a person engages with their surroundings, then the surroundings take part in the reorganization. A clinical room, a forest at dusk, a living room with three trusted people — each is a different world to be opened to. When the habitual filters relax, what a person opens to is the particular place they are in.
The best evidence so far comes from Hannes Kettner and colleagues at Imperial College London, who surveyed 654 people in the week before a planned psychedelic experience and followed them afterward. Their sense of relatedness to nature was higher two weeks, four weeks, and two years later. The size of the increase depended on two things: how much ego dissolution a person reported, and how much the natural surroundings had influenced the experience. The study was observational, with no control group, and only 64 people answered at two years. Within those limits, it points where the enactive account predicts. Psychedelics used in natural settings meet a denser living world, and the experience carries that density.
None of this makes a forest necessary, and none of it guarantees an outcome. Psychedelics tilt experience toward relationship without determining it. An experience can as easily confirm the worldview a person arrived with, including one built on control, achievement, and extraction. The compound lowers the threshold for opening to whatever is present. What is present, and where it directs attention, shapes what remains.
What the Experience Asks Afterward
Reflection after a psychedelic experience usually dwells on its content: what appeared, what was felt, what was understood. The more consequential matter is what changed in how the person relates. A loosened boundary can leave new relationships possible or close again. An insight into interdependence can reorient a person’s attention over years or sit unused as a pleasant memory.
Arne Næss called the wider identity at stake the ecological self: a sense of who one is that extends, through felt identification, into the living world. When that identification widens to include other organisms and places, harm to them registers as harm to something one is part of. The survey respondent who wrote that harming nature would be like hurting themselves was describing precisely this.
The perception can also be kept as a possession. It can circulate as a private depth, a satisfying sense of meaning, while leaving untouched how a person acts and what they are willing to give up. Much of the commercial psychedelic field sells the insight in this form, as an experience to be had, and leaves the conditions of disconnection in place. The Potawatomi botanist Robin Wall Kimmerer states the alternative in one line of Braiding Sweetgrass: “As we work to heal the earth, the earth heals us.” The sentence describes a relationship kept up through effort, which is a different thing from a feeling of connection.
The world a person returns to matters as much as the one the experience happened in. If a psychedelic relaxes deep assumptions, what attention is drawn to in the weeks afterward helps decide which assumptions settle back into place. A culture organized around distraction and consumption pulls attention back toward the old ones, and personal integration has limits when the culture of return is built on disconnection.
The visions are the part of a psychedelic experience that asks nothing. A changed sense of what one belongs to asks a great deal — beginning with whether a person will let it cost them anything.
Sources
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Carhart-Harris, R. L., & Friston, K. J. (2019). REBUS and the anarchic brain: Toward a unified model of the brain action of psychedelics. Pharmacological Reviews, 71(3), 316–344. doi:10.1124/pr.118.017160
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Kettner, H., Gandy, S., Haijen, E. C. H. M., & Carhart-Harris, R. L. (2019). From egoism to ecoism: Psychedelics increase nature relatedness in a state-mediated and context-dependent manner. International Journal of Environmental Research and Public Health, 16(24), Article 5147. doi:10.3390/ijerph16245147
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