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Wednesday, June 15, 2011

Why do blind people have a superior sense of touch? Practice!

Blind people are known to have an enhanced sense of touch compared to sighted people. But what is the cause of this increase in tactile ability? The two top theories are that the blindness itself rewires the brain so that more processing power is applied to the touch centers, and that blind people simply make greater use of their sense of touch. Michael Wong, Vishi Gnanakumaran, and Daniel Goldreich of McMaster University have shown that the latter hypothesis is true: blind people have a greater sense of touch because they practice touching things more often.

The researchers compared 28 profoundly blind people with 55 normally sighted people. Some of the blind participants were proficient in reading Braille. All the volunteers were tested for touch sensitivity on various fingers as well as on their lower lips. If blindness itself led to a increased sense of touch, the blind people should have been more sensitive than the sighted people everywhere on their bodies, including on their lips. This wasn’t the case. Instead, the researchers found that blind people were more sensitive on their fingers than sighted people but all participants were equally sensitive on their lips (which presumably are used equally by both blind and sighted people). In addition, blind people who could read Braille had more sensitive fingers than blind people who could not, and among the Braille readers, the finger they used to read with was more sensitive than their other fingers.

Taken together, these data clearly show that it’s increased usage that leads to increased sensitivity. There was even a direct correlation between the number of hours spent reading Braille and reading-finger sensitivity. As with everything else, practice makes perfect!