A new study finds at least 50 percent of people are able to see even in the pitch dark.
Duje Tadin, a professor of brain and cognitive sciences at the University of Rochester who led the investigation, said that this research shows that their own movements transmit sensory signals that also can create real visual perceptions in the brain, even in the complete absence of optical input.
Through five separate experiments involving 129 individuals, the authors found that this eerie ability to see our hand in the dark suggests that our brain combines information from different senses to create our perceptions.
The ability also "underscores that what we normally perceive of as sight is really as much a function of our brains as our eyes," first author Kevin Dieter, a post-doctoral fellow in psychology at Vanderbilt University said.
The study seems to confirm anecdotal reports that spelunkers in lightless caves often are able to see their hands. In other words, the "spelunker illusion," as one blogger dubbed it, is likely not an illusion after all.
For most people, this ability to see self-motion in darkness probably is learned, the authors conclude.
The study has been published in journal Psychological Science.