Brain Strategies for Building an Image of the Visual World

Our wholesome experience of the visual world, in which all attributes (colour, form, motion, depth) are seen in precise temporal and spatial registration, belies a complex neural apparatus whose hallmark is functional specialization, which leads to the processing of these different visual attributes separately in time and space. One consequence is that, over short presentation times, we perceive and become aware of different visual attributes at different times (for example, we perceive colour some 80 ms before directional motion). This perceptual asynchrony raises profound questions about the strategies used by the visual brain to build an image of the visual world, the neural mechanisms used to bring the separately processed attributes together and the nature of visual consciousness.