Blind people have a better sense of touch than their sighted peers, due to practice, than the brain compensating for vision loss, reveals study.
In the McMaster University study, 28 profoundly blind participants-with varying degrees of Braille expertise-and 55 normally sighted adults were tested for touch sensitivity on six fingers and both sides of the lower lip.
Researchers reasoned that, if daily dependence on touch improves tactile sensitivity, then blind participants would outperform the sighted on all fingers, and blind Braille readers would show particular sensitivity on their reading fingers.
But if vision loss alone improves tactile sensitivity, then blind participants would outperform the sighted on all body areas, even those that blind and sighted people use equally often, such as the lips.
"There have always been these two competing ideas about why blind people have a better sense of touch," said Daniel Goldreich, corresponding author and a professor in the Department of Psychology, Neuroscience and Behaviour.
"We found that dependence on touch is a driving force here. Proficient Braille readers-those who might spend hours a day reading with their fingertips-performed remarkably better. But blind and sighted participants performed equally when the lips were tested for sensitivity," he said.
Not only did blind participants do better than their sighted peers, but Braille readers, when tested on their readings hands, outperformed nonreaders who were also blind.
For Braille-reading participants, their reading fingers were more sensitive than their non-reading fingers.
The study has been published in the most recent edition of the Journal of Neuroscience.