New research has found that in people who have been deaf since birth, the brain’s primary auditory cortex, normally used for hearing, can process touch and vision. According to a National Institutes of Health release, the findings could inform the development of better learning tools for deaf students and improved quality of hearing in children who receive cochlear implants.
From an Atlantic article:
In the study, [Christina M. Karns, PhD] and her colleagues at the University of Oregon strapped 13 deaf volunteers into a head apparatus that delivers a flash of light to the eye (to stimulate vision), along with two bursts of air to the face (to stimulate a touch response). They did the same with 12 hearing peers, and observed the brain responses in all subjects via fMRI.
Karns’ team found that the deaf subjects were not only processing both the touch and visual responses through the hearing part of their brains, but they were also far more likely to associate these inputs through something called the “double flash illusion.”
Using the head apparatus, researchers “flashed a light to each subject’s eye once, and then at the exact same moment we touched their face with two little puffs of air, so that the flash and the puff-puff were right at the same time,” Karns said, explaining her experiment. While deaf subjects reported seeing two flashes, their hearing peers didn’t see anything out of the ordinary, just one burst of light.
“I had the idea that maybe in people born deaf, touch and vision would be interacting more closely because these two senses have had more time to get to know each other during development, without sound monopolizing the conversation in the auditory cortex,” said Karns, “and it turned out to be true.”