Sunday, June 17, 2007

The Man Who Mistook His Wife for a Hat

I'm reading this morning again from In Search of Memory, specifically about cognitive psychology and how our perceptions are stored in the brain. "The belief that our perceptions are precise and direct is an illusion-- a perceptual illusion. The brain does not simply take the raw data that it receives through the senses and reproduce it faithfully." Instead, each sensory system analyzes and deconstructs then reconstructs  the raw incoming information according to its own built-in connections and rules. To summarize, "sensation is an abstraction, not a replication, of the real world.  302

When it comes to vision, aspects of visual perception like motion, depth, form, and color are separated and carried along separate neural pathways to the brain, where they are coordinated into a unified perception. In the primary visual are of the cortex, "what" pathways (information about what an object looks like) are separate from "where" pathways (where it is, how the object is moving in space). Unfortunately, some people have defects in their cortexes and aren't able to put Humpty Dumpty back together again. For example, neurologist-neuropsychologist Oliver Sacks shares how  once upon a time he had a a patient who failed to recognize his wife sitting next to him and, thinking she was his hat, tried to pick her up on his head as he was about to leave the doctor's office. 303 Hope you haven't tried to do that!

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