Normalization Regulates Competition for Visual Awareness

Signals in our brain are in a constant state of competition, including those that vie for motor control, sensory dominance, and awareness. To shed light on the mechanisms underlying neural competition, we exploit binocular rivalry, a phenomenon that allows us to probe the competitive process that ordinarily transpires outside of our awareness. By measuring psychometric functions under different states of rivalry, we discovered a pattern of gain changes that are consistent with a model of competition in which attention interacts with normalization processes, thereby driving the ebb and flow between states of awareness. Moreover, we reveal that attention plays a crucial role in modulating competition; without attention, rivalry suppression for high-contrast stimuli is negligible. We propose a framework whereby our visual awareness of competing sensory representations is governed by a common neural computation: normalization. º Gain modulation under visual rivalry depends on competitor size º Attention plays a substantial modulatory role in visual rivalry º Visual awareness is governed by a common neural computation: normalization Signals in the brain are in a constant state of competition. Here, Ling and Blake propose and test a model in which visual attention plays a key role, driving the ebb and flow between states of visual awareness