A joint study by the University of Rochester in New York and Vanderbilt University in Tennessee suggests that fifty per cent of people can see and follow their own body movements in the dark.
The study was conducted on 129 participants from Rochester, Nashville and Seoul, a certain number of whom were synesthetes, or people who experience a blending of their senses which allows them, for instance, to see numbers or letters in different colours when they read.
During the experiment, participants were first asked to wear a blindfold which seemed to have holes in it. The researchers told them that they would see movements in low lighting. They were then given a blindfold without any holes and told that they would not see anything. In fact, none of the blindfolds had any holes that would allow participants to see.
Participants were asked to wave their hands in front of their eyes and try to see the hand of a researcher who was also waving a hand. An eye-tracking device followed their eye movements. Although none of the participants was able to detect the movements of the researcher's hand, half of them were able to see and follow the movements of their own hand, which means, according to the researchers, that hand movement sends a visual signal to the brain. Synesthetes were particularly skilled at seeing movements, one of whom was even able to see almost as well in the dark as in the light.
This research shows that our own movements transmit sensory signals that also can create real visual perceptions in the brain, even in the complete absence of optical input, explains Professor Duje Tadin, from the University of Rochester.
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