Phase-dependent EEG decoding of continuous visual stimuli

Neural oscillations support cognition and perception by organizing information across oscillatory cycles. Although animal studies support this view, evidence in humans is mixed and largely based on transient stimuli. We tested whether alpha oscillations, the dominant human brain rhythm, periodically modulate the strength of visual representations. EEG was recorded while participants viewed long-lasting (2 s) Gabor patches. Using a phase-dependent decoding approach, we quantified stimulus decoding accuracy at specific alpha phases. Decoding performance varied systematically with alpha phase, following a smooth unimodal profile that peaked over occipito-parietal electrodes. These effects emerged well after stimulus onset and generalized to earlier time points, indicating a modulation of visual processing during continuous input. Our findings demonstrate that visual information is represented more accurately at specific alpha phases. This provides strong evidence that sensory processing is shaped by intrinsic brain dynamics and introduces a generalizable decoding pipeline for linking oscillatory phase to neural information processing.