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Name: Tyler
Location: Mountain View, California, United States

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Saturday, August 30, 2008

mistaking your wife for a hat

In 1985, neurologist Oliver Sacks published the book The Man Who Mistook His Wife for a Hat - a collection of 24 essays exploring fascinating case studies in neuropsychology. The title essay describes a man suffering from a form of visual agnosia - a result of brain damage in which vision is intact, but comprehension of vision is impaired.

For some reason, the man in question is able to see and understand the general shape of things, but has immense trouble "seeing" people and certain other things. The most curious example is the case when, as the man was leaving an office, he searched for his hat, and apparently attempted to remove his "hat" from the top of his wife's head. Since he could understand that the top of her head was hat-shaped, he surmised that it must be the hat he was looking for.

In another case, he was easily able to recognize a wristwatch. Yet, when he was shown a glove, he had a great deal of trouble calling it a "glove", or recalling its function. Instead, he was able to very accurately describe its general shape - a flexible series of tube-like structures ending in half-spherical tops, all joined at one end with a hole. In general, he had a great deal of trouble recognizing people and familiar faces, including his own wife.

I would like to add a hypothesis to the essay: that this form of agnosia suggests a neurological dichotomy between recognition of organic vs inorganic objects. Basically, this story fits the idea that there's one part of the brain designed to recognize many natural objects - faces, hands (& gloves), dogs, cats, etc - and another part designed to recognize artificial or learned objects - wristwatches, tubes, cubes, etc. Such a dichotomy also makes sense evolutionarily, since brains that had built-in recognition of things that it could "evolutionarily know" were around, such as familiar human faces, would have a great survival advantage. The human race probably hasn't had wristwatches long enough to evolve a glob of neurons just for them, so we may store the visual recall center for watches in a more learning-oriented part of the brain.

By the way, if you have any interest whatsoever in curious neuropsychological phenomena (who doesn't??), I highly recommend Sack's book. It also includes a case of a "Jimmy G." who suffers from Korsakoff's syndrome (to simplify - severe amnesia) which I'm guessing was an inspiration for the (very cool) movie Memento; and another case about an elderly woman who's happy to be suffering the tertiary stages of a usually fatal disease, which I'm guessing was an inspiration for a certain subplot in an episode of House, MD :)

PS Tangent: why does it "sound wrong" to say "an usually fatal disease" when I know that's grammatically correct?