Time²: A Framework for the Neural Dynamics of Visual Perception

Whenever we look at an object, we seem to perceive it immediately. However, this is not the case for two reasons. First, it takes hundreds of milliseconds for the brain to process visual information reaching the retina. Second, perceiving an object requires fixating it for some duration-typically hundreds of milliseconds-during which the retina continuously receives new visual information. These facts together imply that visual information is both processed and received through time. These two temporal facets of perception, which we term processing time and stimulus time, are often conflated in the literature, and rarely considered together in experiments. Here, we argue that, to obtain a more complete portrait of visual perception and further constrain models of vision, it is essential to consider and measure both temporal facets simultaneously. We present a new method designed to do so that is based on reverse correlation: Time² We show that this method allows us to precisely characterize many neural phenomena, including rhythmic perception, predictive processing, and coarse-to-fine sampling.