For most people, dreams are a largely visual experience; when we can't see and start stumbling through the dark, we call it a nightmare.
But what if you can't see to begin with? For blind people, dreaming is an entirely different experience. As Virginia Hughes writes at National Geographic, "Blind people dream, just as they live, with a rich mix of sensory information."
A group of researchers recently showed this by recruiting 50 people to take part in a dream-recording experiment. Some of the participants had been blind since birth, some had gone blind later in life and some possessed normal vision. For four weeks, all of them reported on their dreams, including any sensory experiences incorporated into those dreams. Here's Hughes on what they found:
About 18 percent of the blind participants (both congenital and later-onset) reported tasting in at least one dream, compared with 7 percent of controls. Nearly 30 percent of the blind reported smelling in at least one dream, compared with 15 percent of controls. Almost 70 percent of the blind reported a touch sensation, compared to 45 percent of controls. And 86 percent of the blind reported hearing, compared with 64 percent of controls.
For those who had been blind from birth, the sensory differences were even more drastic when compared with the group that could see.
As for the themes of those dreams, Hughes reports that they were largely the same across the board: interpersonal conflicts and encounters, success and failures in life and work and other normal dream scenarios. The blind, however, had more nightmares than those who could see—about 25 percent, compared to the 7 percent of sighted people. And the content of those nightmares? "Events such as getting lost, being hit by a car, falling into manholes, and losing their guide dog — all very real threats in their waking lives," Hughes writes.