Abstract
Binocular rivalry occurs when disparate images are shown simultaneously but separately to each eye. Perceptually dominant images reverse over time, with one image temporarily dominating perception while the other is suppressed. Probes presented to the suppressed eye are typically seen by participants and tend to cause perception to shift to the suppressed image. Here we ask why perception shifts to the suppressed eye. One possibility is that the probe draws attention to the suppressed eye/image. Prior fMRI research has implicated regions of the dorsal attention network in binocularly rivalry reversals more generally, and EEG research has shown specifically that suppressed-eye probes presented during binocular rivalry elicit larger ERP P3 responses, which have been associated with attentional orienting and allocation, compared to dominant-eye probes. We combine behavior, EEG, and fast event-related optical imaging (EROS) to test the hypothesis that suppressed-eye probes are eliciting a shift in attention to the suppressed image. We find enhanced ERP N2 amplitude, which is thought to index attentional processing, followed by enhanced P3 amplitude for suppressed-eye probes compared to dominant-eye probes. Most notably, greater single-trial P3 amplitude evoked by suppressed-eye probes was correlated with faster subsequent switches to the suppressed image, suggesting the P3 may play a critical role in the switch. Furthermore, EROS data show greater activity for suppressed-eye probes compared to dominant eye-probes occurring in visual cortex and right intraparietal sulcus starting around 400 ms. followed by greater activity in right dorsolateral pre-frontal cortex starting around 700 ms., all of which occurs before the subsequent switch is complete. These later regions belong to the dorsal attention network, thus again implicating attention in the switch. Together, the behavioral, ERP, and EROS data indicate suppressed-eye probes are followed by classic neural markers of attention which may be critical to eliciting a reversal to the suppressed image.
Meeting abstract presented at VSS 2014