Neuroscience of consciousnessAug 21, 2026

Low-dose LSD changes how people see visuals without affecting visual contrast processing

Psychedelic Science Weekly Brief ↗PubMed ↗DOI ↗OA ↗

Updated Aug 22, 2026

Abstract

Low-dose Lysergic Acid Diethylamide (LSD) did not measurably influence contrast surround suppression in a study with 30 participants.

Psychedelics may alter perception by changing contextual influences.
Contrast surround suppression is a visual illusion where a grating's contrast appears lower in a high-contrast background.
While low-dose LSD did not affect contrast surround suppression, participants reported subjective visual changes.
These reported changes included perceptions of blurrier, more saturated, and more dynamic visuals.
No correlation was found between the subjective visual alterations and the measured contrast surround suppression.
The findings suggest that the subjective effects of low-dose LSD could involve different mechanisms than those affecting early visual processing.

Simplified

Theoretical models and empirical evidence suggest that psychedelics alter contextual influences on perception. To test this, we examined contrast surround suppression, a visual illusion in which a grating appears lower in contrast when embedded in a high-contrast surround. While psilocybin has been reported to enhance this and related illusions at moderate-to-high doses, it is unknown whether low-dose Lysergic Acid Diethylamide (LSD) produces similar effects. In a randomized, double-blind, within-subjects crossover study, N = 30 healthy participants received placebo, 10, and 20 μg of LSD (base-equivalent). In each session, participants performed a contrast discrimination task and rated subjective drug effects. LSD did not measurably influence contrast surround suppression. However, participants reported subjective visual changes, including blurrier, more saturated, and more dynamical visual perception. These subjective alterations did not correlate with individual differences in contrast-surround suppression. Our findings indicate a dissociation between subjective experience and early visual contextual processing, suggesting that subjective visual effects of low-dose LSD may arise through mechanisms distinct from those mediating contrast surround suppression. Future research should test whether higher doses of LSD affect contrast surround suppression.

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Low-dose LSD changes how people see visuals without affecting visual contrast processing

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