Multivariate decoding of EEG data reveals similar mechanisms mediate perceptual adaptation and spontaneous perceptual reversals

Abstract

The cause of spontaneous perceptual reversals of visually ambiguous stimuli (e.g., Rubin’s faces-vase) has been attributed to several different mechanisms. One hypothesis suggests that adaptation, or “neural fatigue”, builds up while one interpretation is dominant and eventually triggers a reversal in perception. Although there is behavioural evidence that adaptation to an unambiguous stimulus (i.e., adaptor) can bias subsequent perception of an ambiguous one, it is unclear whether adaptation plays a role in spontaneous reversals (i.e., no adaptor). We used multivariate pattern analysis of human EEG data to test whether adaptation is involved in spontaneous perceptual reversals. We presented two block types: adaptation and ambiguous. In adaptation blocks, perceptual reversal was induced by adapting to an unambiguous motion stimulus before presentation of an ambiguous stimulus. During ambiguous blocks, only ambiguous stimuli were presented, and any reversals occurred spontaneously. We trained a classifier on the pattern of EEG scalp voltage during adaptation-induced reversals. We then tested this classifier on spontaneous reversal data and found above-chance decoding and similar activity patterns. These results suggest that similar brain mechanisms mediate perceptual adaptation and spontaneous perceptual reversals. This provides support for the “neural fatigue hypothesis” of multi-stable perception.