Hypnosis reduces decoding accuracy of visual and auditory representations

This study used event-related potentials (ERPs), time-frequency analysis, and multivariate pattern analysis (MVPA) to investigate how hypnosis modulates visual and auditory processing. Twenty-two highly hypnotizable participants performed an independent oddball task. Under the hypnotic suggestion of "seeing without perceiving, hearing without listening," behavioral results showed that hypnosis reduced target detection accuracy and prolonged reaction times in both modalities, while false alarm rates remained low. ERP analysis revealed no significant difference in the N100 component between hypnosis and wakefulness, but hypnosis attenuated the late cognitive evaluation reflected by the P300 component. MVPA further showed that hypnosis delayed the onset of neural decoding to 160 ms in the visual pathway and to 120 ms in the auditory pathway from a baseline of 80 ms, and also reduced the temporal stability of neural representations. Time-frequency analysis of the visual task indicated that in the wakeful state, target stimuli elicited stronger delta-band (1-4 Hz) power than distractors, whereas hypnosis significantly diminished this neural representational specificity. These findings suggest that when individuals internalize hypnotic suggestions as personal goals, top-down regulatory mechanisms may alter neural temporal dynamics, reduce representational specificity, and lead to more homogeneous neural coding patterns, thereby decreasing perceptual efficiency while retaining weak decodability. This study provides neurobiological evidence for the neural mechanisms underlying perceptual dissociation during hypnosis.