Echolocation, the ability to “see” the surrounding landscape by interpreting echoes, allows blind teachers Daniel Kish and Brian Bushway to use tongue clicks and echoes to get around. In many cases, sighted people have 20/20 vision to blame for not being able to pull off the same stunt. At least that’s the working theory being pursued by University of Western Ontario researchers who have studied the brains of the human echolocators.
MRI scans show that Kish and Bushway “process the echoes of their clicks with parts of their brain that are usually devoted to vision, rather than hearing,” writes Ed Yong at Discover.com (May 25, 2011). In contrast, sighted men showed zero activity in that part of the brain when they were listening to the same echoes.
The preliminary findings are exciting. Scientists know that the loss of one sense can sharpen the others. Until now, though, no one pursued the theory that certain senses may be mutually exclusive. The MRIs suggest that “echolocation and vision compete for the same part of the brain–the calcarine cortex,” writes Yong. “Maybe, in humans at least, [the two] senses cannot coexist easily.” (Presumably dolphins and bats, renowned echolocators, don’t struggle with the overlap.)
Kish and Bushway teach echolocation through World Access for the Blind, opening up activities like soccer, basketball, hiking, and mountain biking to students. As Yong explains, “echoes are loaded with information, not just about the position of objects, but also about their distance, size, shape, and texture.”
The MRIs speak to the powerful adaptability of the brain when a person is deprived of one of the senses. And while Yong concedes that the new study is too small to be conclusive, he notes that “echolocators aren’t exactly easy to recruit in large numbers.”