What is meant by the "what" versus "where" systems in visual perceptual processing? Name and explain an example of a neuropsychological syndrome caused by damage to the what system and a neuropsychological syndrome caused by damage to the where system.

Question

What will be an ideal response?

Answer 1

Visual information arriving at the occipital lobe cortex is processed further by cortical brain areas that go up toward the parietal lobe and also by cortical brain areas that go down toward the temporal lobe. The processing that goes toward the temporal lobe is sometimes called the what system because this system focuses on establishing the identity of the visual inputs. The processing that goes toward the parietal lobe is sometimes called the where system because this system focuses on processing the spatial information associated with visual inputs, that is, where the input is coming from. Visual object agnosias are one example of the results of damage to the what system. In visual object agnosias, people can still see and may even describe things about what they see. But they cannot identify what it is that they are seeing. The problem is specific to vision, as they can still identify objects based on touching, smelling, or sometimes hearing them. But if the person can only look at these objects, he or she may not be able to say what the objects are. Simultanagnosia is an example of damage to the where system. In this condition, people can see the individual parts of a visual scene, but they cannot spatially group them together to see the entirety of the scene. For example, when looking at a pattern made up of small letter "T's" arranged to form a large letter "H," people with simultanagnosia can see all the T's, but they cannot see the H. It is as if they see the trees, but not the forest.