Mind & Body

Visual Agnosia Is Why The Man Mistook His Wife For A Hat

We've told you about prosopagnosia, or face blindness, which is a condition that's pretty difficult to live with. But the inability to tell people's faces apart is a walk in the park compared to visual agnosia. Imagine having perfectly clear vision, but not being able to tell if you were looking at the person that you married or an article of clothing. Meet the man depicted in Oliver Sacks's famous book, "The Man Who Mistook His Wife For A Hat."

A Convoluted Red Form by Any Other Name Would Smell As Sweet

"About six inches in length. A convoluted red form with a linear green attachment... [It's] not easy to say [what it is]. It lacks the simple symmetry of the Platonic solids, although it may have a higher symmetry of its own." This is Dr. P, who neurologist Dr. Oliver Sacks diagnosed with visual agnosia, attempting to describe... something. Do you have any idea what it is? Neither did he — until he took a sniff. "Beautiful!" he said, finally. "An early rose. What a heavenly smell!"

The thing about Dr. P and other people with visual agnosia is that they can see perfectly fine. They just can't put what they're seeing together into a coherent picture. That's why Dr. P had no problem identifying geometric shapes, or describing the individual parts of a rose, but couldn't identify how those parts added up to a beautiful flower.

That's frustrating if you're trying to buy Dr. P a romantic bouquet, or if you're waiting for him to find his glove (which until he got it on, he described as "a continuous surface infolded on itself. It appears to have five outpouchings, if this is the word.") But imagine if you're his wife. There's a pretty good chance he won't recognize you at all. He might not even realize you're a human being.

In the book's titular incident, Dr. P attempted to lift his own wife's head from her shoulders, believing that she was the hat that he had worn to his appointment. In Dr. Sacks' words, "His wife looked as if she was used to such things." We understand why she insisted he go in to see the doctor.

A World in Bits and Pieces

This isn't the same thing as face blindness. People with that condition can recognize that something is a face, they just have a hard time telling faces apart.

Visual agnosia is the strongest expression of agnosia, an umbrella term for the inability to process sensory information. A person with this condition experiences the entire world in little bits and pieces, and has to put them together on their own. If one of those pieces is particularly prominent, they might have an easier time doing so — you just need to see the chin to know you're talking to Bruce Campbell.

But sometimes even recognizing one prominent feature can lead you far astray. In one experiment, Dr. Sacks showed Dr. P a photograph of the Sahara desert. There's no way to know what, but something in the barren picture made Dr. P think of a river. From there, he began to "see" many other things — people dining on the river bank, expansive terraces, and even colorful parasols. It shows the danger of jumping to conclusions, but somebody with this condition doesn't have many other options.

Want to find out more about agnosia? Check out Oliver Sacks' "The Man Who Mistook His Wife for a Hat", where you'll also meet a man who has been unable to form new memories since World War II, and a pair of mathematical savants on the autism spectrum who seem to have an innate sense of prime numbers.

Oliver Sacks on Manipulating the Brain

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Written by Reuben Westmaas November 26, 2017