ABSTRACT
The primacy of the visual system in humans is reinforced by the observation that up to half of the cerebral cortex is directly or indirectly involved in visual processing. It is important at the outset to try to distinguish between sensory mechanisms of vision and perceptual processes that permit recognition of the visual input. Essentially, visual sensation is about input “getting registered” in the brain. Perception is concerned with interpretation of that input (Mesulam, 1998). The latter is what principally concerns us here, and we will consider research findings from case studies of people who have lost certain perceptual functions, usually after damage or disease to key cortical regions, as well as findings from functional brain imaging.
