Psilocybin-induced modulation of visual salience processing
Psychedelic compounds significantly reshape conscious perception, yet the implications of these alterations for complex visual-guided behaviors remain poorly understood. We investigated how psilocybin modulates visual salience processing during natural scene perception. Twenty-three participants completed eye-tracking tasks under self-blinded low and high doses of psilocybin, in a naturalistic design with experimental conditions unknown to participants and researchers. Subjects viewed natural scenes while their gaze patterns were recorded and analyzed in relation to normative computational saliency maps generated using a deep learning model of visual attention. Results revealed increased fixation on salient image regions and reduced inter-fixation distance under the high-dose condition, suggesting heightened sensitivity to visual salience and more localized gaze behavior. The Shannon entropy of fixations on high-saliency regions indicated a more exploratory and less predictable visual scanning of the images. Complementary EEG recordings showed broadband spectral power reductions and increased Lempel-Ziv complexity, with delta power negatively correlating with salience metrics. These findings suggest psilocybin enhances bottom-up attentional control while weakening top-down modulation, consistent with theoretical models positing facilitated bottom-up information flow under the acute effect of psychedelics.