There are lots of reasons people take psychedelic drugs: Recent studies, for instance, suggest they may be effective for treating disorders like anxiety and depression, as well as addiction. Sometimes, people are just looking to learn something new and profound about themselves or the world. Or maybe they're just looking for an escape. The hallucinations that occur under the influence of psychedelics often play a big part in these treatments and epiphanies—people often report seeing textures and shapes transform. Static objects appear to breathe. And, of course, people see objects that aren't really there.

Visual stimuli play such an important role in the use of psychedelics, in fact, that it begs the question how the experience might change if the person taking them lacks the sense of sight. Ilsa Jerome, a clinical researcher for the Multidisciplinary Association for Psychedelic Studies (MAPS), recently set out to answer that question. Jerome is visually impaired, yet much of her research focuses on psychedelic drugs. We asked her how that changes the experience of using psychedelics like LSD and psilocybin—and what blind people still have to gain from taking them.

Let's start with the basics: What happens when someone who's never had sight takes a psychedelic drug? What's it feel like?

Classic psychedelics produce the same changes in mood—they greatly intensify positive and negative feelings—and perception and sense of self as they do in people who aren't blind. The difference, as you might expect, is that people who are blind report seeing less complex imagery than people who aren't blind. They also report a greater number of auditory, tactile, and somatic (body-related) sensations, perhaps due to their already heightened sense of touch and hearing. But from what the research shows, the experience does not appear to be any more or less frightening or pleasant. **Are the effects of psychedelics—much like other senses—heightened for a blind person?**The scant literature doesn't allow us to answer this question easily, but the absence of any such reports from what studies do exist suggests that the effects are not heightened. We can't say for certain, however, since there are no studies directly comparing the blind to people with normal eyesight.

If someone is partially blind, can they see clearer images when they're hallucinating? People who report seeing more clearly may be doing so because the psychedelics make them draw more fully on their visual memory and past experiences. But psychedelics also increase the perceived importance of experiences. So it might be the case that people with visual impairments who report seeing more clearly are being influenced by the intensity and significance of the experience, but not its actual clarity. At any rate, we don't have enough data to make a definitive conclusion.

So you think they can only see abstract images?

In the study of 24 people that I described before, researchers tape recorded blind subjects' responses to questions about what they experienced, and they reported seeing spots, lights, dots, and flickers. Very few reported "complex" visual imagery—like faces or objects—or even colors. But these were eye researchers, not psychologists. They were exploring a hypothesis about the retina that proved to be wrong—that LSD caused changes in the retina, and these changes would be associated with hallucinations. It turned out that, while LSD did change retinal electric signals, these weren't associated with hallucinations. Unfortunately, those researchers weren't interested in the experience as a whole, which is too bad. We don't know if the imagery that participants saw was enjoyable or disconcerting. How much other research has been done on blindness and psychedelic use?

Very little. The study with the largest sample was a placebo-controlled study looking at the effects of LSD in 24 people who were totally blind at the time. The authors of this study referred to an early investigation of mescaline in ten blind participants. Another very small study looked at the effects of LSD in two people without eyesight—a couple of participants who received LSD. These studies, it's worth pointing out, did not have placebo controls.

Also, the researchers in those studies mainly wanted to test how LSD affected the retina—they weren't necessarily interested in comparing the experiences of blind people to those with sight. At the time, we were just starting to develop a more sophisticated understanding of the way psychedelics work on the brain. So, the short answer is that very little research on psychedelics and blindness exists, but fortunately, some people did consider the idea and pursue it when the research was easier to conduct.

Is more research ahead?

It's still difficult and expensive to conduct these studies, so I'm not hopeful that the renaissance in psychedelic research will lead more studies on the blind or people with other sensory impairments. There's very little impetus: The assumption that these questions are "trivial" may be correct—the effects of psychedelics extend far beyond sensory changes. The more profound changes in emotion and ego matter much more—and, as we've said, they appear to be the same whether you're blind or not.