SOMERS, N.Y. — At least 50 percent of people can see the movement of their own hand even in the absence of all light, according to a new study.
Kevin Dieter, a postdoctoral fellow at Vanderbilt University, devised experiments to study the phenomenon.
How does Dieter explain the finding?
"What we normally perceive of as sight is really as much a function of our brains as our eyes," said Dieter, echoing the study's claim published in the journal Psychological Science.
The idea for the study came from cognitive science professors Duje Tadin of Rochester University and Randolph Blake of Vanderbilt, who stumbled upon the occurrence while devising experiments for an unrelated study.
The felt they could see their hands through an opaque blindfold.
"They could see their hand when no light was coming in," Dieter said.
A few years later, Dieter formulated five experiments with 129 individuals.
Using infrared light and eye-tracking cameras that could monitor eye movements even in complete darkness, the researchers found that about half the participants were able to follow their moving hand in the absence of light.
The authors, found that the ability of a subject to see their hand in the dark suggests that their brain combines information from different senses to create our perceptions.
"Seeing in total darkness? According to the current understanding of natural vision, that just doesn't happen," said Tadin, who led the investigation, in a statement. "But 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."
For most people, this ability to see their own motion in darkness is probably learned, the authors concluded.
"We get such reliable exposure to the sight of our own hand moving that our brains learn to predict the expected moving image," Dieter said. "It is a learned association."