Enhanced visual contrast suppression during peak psilocybin effects: Psychophysical results from a pilot randomized controlled trial
Sophia Jungers, Ranji Varghese, Link Swanson, Kathryn R. Cullen, Michael D. Evans, Jessica L. Nielson, Michael‐paul Schallmo
Journal of Vision November 5, 2024 DOI: 10.1167/jov.24.12.5 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Randomized controlled trial Peer reviewed |
|---|---|
| Sample size | 6 |
| Population | Human participants |
| Intervention | Psilocybin |
| Dose | 25 mg |
| Topics | Psilocybin |
| Keywords | Contrast vision Randomized controlled trial Audiology |
| Citations | 2 |
| Key findings | Psilocybin increased surround suppression of perceived contrast, and the strength of subjective visuals correlated with the magnitude of this effect. |
Abstract
In visual perception, an effect known as surround suppression occurs wherein the apparent contrast of a center stimulus is reduced when it is presented within a higher-contrast surrounding stimulus. Many key aspects of visual perception involve surround suppression, yet the neuromodulatory processes involved remain unclear. Psilocybin is a serotonergic psychedelic compound known for its robust effects on visual perception, particularly texture, color, object, and motion perception. We asked whether surround suppression is altered under peak effects of psilocybin. Using a contrast-matching task with different center-surround stimulus configurations, we measured surround suppression after 25 mg of psilocybin compared with placebo (100 mg niacin). Data on harms were collected, and no serious adverse events were reported. After taking psilocybin, participants (n = 6) reported stronger surround suppression of perceived contrast compared to placebo. Furthermore, we found that the intensity of subjective psychedelic visuals induced by psilocybin correlated positively with the magnitude of surround suppression. We note the potential relevance of our findings for the field of psychiatry, given that studies have demonstrated weakened visual surround suppression in both major depressive disorder and schizophrenia. Our findings are thus relevant to understanding the visual effects of psilocybin, and the potential mechanisms of visual disruption in mental health disorders.
Comparable studies
Other randomized controlled trials on psilocybin, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| Psilocybin produces substantial and sustained decreases in depression and anxiety in patients with life-threatening cancer: A randomized double-blind trial Cancer patients with life-threatening diagnoses and symptoms of depression and/or anxiety | 2016 | Randomized controlled trial | n = 51 |
| Rapid and sustained symptom reduction following psilocybin treatment for anxiety and depression in patients with life-threatening cancer: a randomized controlled trial Patients with cancer-related anxiety and depression | 2016 | Double-blind, placebo-controlled, crossover trial | n = 29 |
| Psilocybin can occasion mystical-type experiences having substantial and sustained personal meaning and spiritual significance Hallucinogen-naïve adults reporting regular participation in religious or spiritual... | 2006 | Double-blind study | n = 36 |
| Trial of Psilocybin versus Escitalopram for Depression Selected group of patients with depression | 2021 | Randomized controlled trial | |
| Effects of Psilocybin-Assisted Therapy on Major Depressive Disorder Adults aged 21 to 75 years with major depressive disorder, not currently using... | 2020 | Randomized controlled trial | n = 24 |
Citations in the library
Cited by 4
- Psilocybin alters visual contextual computations. Nature Communications November 21, 2025
- A Comparative Neurophenomenology of the Psychedelic State and Autism: Predictive Processing as a Unifying Lens Psychoactives November 14, 2025
- Low-dose lysergic acid diethylamide alters subjective visual perception but not visual contrast surround suppression. Neuroscience of Consciousness August 20, 2026
- Cellular mechanisms of serotonergic psychedelics - apical hypercontextualisation. Neuroscience & Biobehavioral Reviews July 1, 2026
Cites 42
- Psilocybin produces substantial and sustained decreases in depression and anxiety in patients with life-threatening cancer: A randomized double-blind trial Journal of Psychopharmacology November 30, 2016
- Rapid and sustained symptom reduction following psilocybin treatment for anxiety and depression in patients with life-threatening cancer: a randomized controlled trial Journal of Psychopharmacology November 30, 2016
- Effects of Psilocybin-Assisted Therapy on Major Depressive Disorder JAMA Psychiatry November 4, 2020
- REBUS and the Anarchic Brain: Toward a Unified Model of the Brain Action of Psychedelics Pharmacological Reviews June 20, 2019
- Single-Dose Psilocybin for a Treatment-Resistant Episode of Major Depression. New England Journal of Medicine November 3, 2022
and 37 more in the library