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Talking back

Talking back

A science blog, sans blague

A Blind Person Understands The Way A Sighted Friend “Sees” The World

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Trendiness in the brain sciences often has an obscure, esoteric quality that belies the prominence accorded neuro in both academia and popular culture. Toward the top of the list of arcana resides the ponderously titled "embodied cognition." This is the idea that cognitive processes—thought, emotion—arise from our interactions with the physical world around us. Reduced to its simplest level: holding a warm tea cup might make you feel well disposed toward your lunch guest.

Some of the proponents of embodied cognition take all this much further, postulating that the way we reason about how others think—essential to social interactions—musters the same mental processes brought to bear when we perceive the world around us. So when we imagine a child seeing a clown at the circus, we use the same visual pathways that we would if we were ourselves seeing the big red nose and the oversize floppy shoes. Taken to its logical extreme, this idea would imply that a visually impaired person might somehow be unable to fully develop a mental picture of the child's trip to the circus.

If this strikes you as a little too facile, you're not alone. Some neuroscientists—experimentalists as well as theorists—wonder whether sensory inputs are necessarily as paramount in shaping subjective mental states as the embodiment proponents would have us believe. Jorie Koster-Hale, a graduate student at MIT in the research group of Rebecca Saxe, decided to put to the test the idea of "embodiment" by asking whether you really need to be able to see the world around you to understand what it means for another person to do the same.

She and her team put nine congenitally blind people and 13 sighted individuals into a functional MRI scanner and asked them to listen to stories about other people immersed in an experience that required either seeing or hearing. "When she gets home from the store, Gladys sees a note on her front door from one of her friends." Or: "When she gets home from the store, Gladys hears a new telephone message from one of her friends."

In a person with normal vision, listening to these stories elicits activity in the brain regions associated with social cognition—reasoning about other people's minds. One of these areas shows a different pattern of activity when reasoning about the way other people are seeing something as opposed to hearing it—seeming support for embodied cognition. But it turns out that the brain region involved—the temporoparietal junction—has a similarly distinctive pattern of activation for the congenitally blind people in the study, according to preliminary research that Koster-Hale reported at the recent Society for Neuroscience meeting.

The blind people in the study had the same contrasting neural responses as the sighted participants. So maybe cognition isn't always so embodied. "What this work suggests," says Koster-Hale, "is that not being able to see doesn't limit your ability to build a mental model about somebody else being able to see."

Source: Mike 384/Wikimedia Commons

The views expressed are those of the author and are not necessarily those of Scientific American.

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