People who use sign language can experience synesthesia, a rare condition that mixes sensory information from different sources, causing people to see letters in certain colors, or taste words, a new study finds.
The study is the first to document synesthesia among sign language users, the researchers said. The people in the study reported that they saw different colors when they watched someone make the signs for various letters and numbers.
The finding shows that “synesthesia occurs in sign language as well as spoken language,” said study lead researcher Joanna Atkinson, a researcher at the Deafness, Cognition and Language Research Centre at University College London. The condition occurs in about 4 percent of the population, including those who experience it with braille letters or while reading sheet music, the researchers said.
Synesthesia is thought to happen because of the wiring in the brain, the researchers said. For instance, this wiring may lead to “cross-activation in neural areas that do not usually interact.”
Read more: Live Science