Fluency in Sign Language May Sharpen Peripheral Vision

A small new study found that people fluent in sign language had significantly better peripheral vision and reaction time than people who couldn’t sign. The research was published in the journal Frontiers in Psychology.

Researchers in the UK recruited 17 people who had been deaf since birth, eight hearing people fluent in British Sign Language (BSL), and 18 hearing people who didn’t sign at all. They brought everyone in to the laboratory and sat them down in front of computers to test their visual acuity, range, and reaction time.

Participants who had been signing from a young age fared far better than the other participants on visual tasks. “Deaf people have exceptional visual abilities that hearing adults do not,” lead author Charlotte Codina of the University of Sheffield said in a statement. “We found that deaf adults have faster reaction times around the whole of the visual field, extending as far as 85 degrees peripherally near the edge of vision.”

These results were unsurprising to Codina and her colleagues. The idea of sensory compensation—experiencing improvement in one sense when another is limited—is, by now, quite well established.

Less expected was that while deaf participants’ scores were the most impressive, they were followed by another group: hearing people who worked as BSL interpreters. These results suggest that fluency in sign language requires or builds visual processing skills that non-signers don’t have, and that adulthood is not too late to learn and benefit from the language.

BSL is not the only form of sign language used in the UK, but it is the most common. It includes a finger-spelled English alphabet, but is otherwise quite different from spoken English.

This was a small study, conducted on small groups of adults in a small country, but the researchers believe their results can be validated in future studies.