What Is Seeing? How Visual Memory Is Affected by Agnosia and Alzheimer’s Disease

Abstract

Almost half of our brain — about 27 cortical areas — is concerned with visual perception. Everyone needs to be able to see the world correctly and orient himself in it in order to survive. If the number of visual areas or the amount of visual modules³ are anything to go by, seeing and understanding must be one of the most complex happenings in our brains, though we never notice how complicated it is. If we are to use them properly, we have to put a conscious effort into learning walking, swimming, logical thought, sensible judgement, languages, mathematics, sciences and many other things, but nothing, apparently, could be simpler than seeing. We seem to be born with the ability; everyone can see. So why bother to think about it?