Forward modelling reveals dynamics of neural orientation tuning to unconscious visual stimuli during binocular rivalry

Abstract

When different visual stimuli are presented to the two eyes, they typically compete for access to conscious perception, a phenomenon known as binocular rivalry. Previous studies of binocular rivalry have shown that neural responses to consciously suppressed stimuli are markedly diminished in magnitude, though they may still be encoded to some extent. Here we employed multivariate forward modelling of human electroencephalography (EEG) data to quantify orientation-selective responses to visual gratings during binocular rivalry. We found robust orientation tuning to both conscious and unconscious gratings. This tuning was enhanced for the suppressed stimulus well before it was available for conscious report. The same pattern was evident in the overall magnitude of neural responses, and it emerged even earlier than the changes in neural tuning. Taken together, our findings suggest that rivalry suppression affects broadband, non-orientation selective aspects of neural activity before refining fine-grained feature-selective information.