Thaindian News

Toronto, May 12 (IANS) Do the blind have a better sense of touch because the brain compensates for loss of vision or because of heavy reliance on their fingertips? A study says that daily dependence on touch is the answer.

Twenty-eight 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, reports the Journal of Neuroscience.

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, according to a McMaster University statement.

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,” explains Daniel Goldreich, study co-author and professor in psychology, neuroscience and behaviour, McMaster University.

“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.”

Researchers used a specially-designed machine which held the pad of the participant’s fingertip perfectly still for the experiments. While the finger lay over a hole in the table, the machine pushed rods with textured surfaces through the opening until they met the fingertip.

Not only did blind participants do better than their sighted peers, but Braille readers, when tested on their readings hands, outperformed non-readers who were also blind. For Braille-reading participants, their reading fingers were more sensitive than their non-reading fingers.

“Braille is extraordinarily difficult to master, particularly as an adult. In future we may find new ways to teach Braille to people who have recently become blind.”