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Brain enables sight without light

Even in total darkness, people often see glimmers of their own hands moving

DARKNESS VISIBLE  A volunteer wears an eye-tracking device as she reenacts a study, in which blindfolded people could vaguely see their hands moving in total darkness. Researchers say the feat may be possible because of connections between the brain’s motion and visual senses.

Many people can vaguely see their own hands moving in total darkness, thanks to brains that pick up slack for the eyes.

Sight without light is no figment of the imagination, say psychologist Kevin Dieter of the University of Rochester in New York and his colleagues. A person’s movements transmit sensory signals that the brain turns into visual perceptions of that motion, even if the eyes see nothing, the researchers propose October 30 in Psychological Science. The brain learns to associate the sight of one’s own hands in motion with the bodily sensations accompanying that activity.

The findings back up cave explorers’ accounts of having seen their hands as they scrambled through lightless underground spaces.

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