Blind, Yet Seeing: The Brain’s Subconscious Visual Sense

The man, a doctor left blind by two successive strokes, refused to
take part in the experiment. He could not see anything, he said, and
had no interest in navigating an obstacle course — a cluttered
hallway — for the benefit of science. Why bother?

Related

Video: Seeing Without Sight
Times Health Guide: Blindness

When he finally tried it,
though, something remarkable happened. He zigzagged down the hall,
sidestepping a garbage can, a tripod, a stack of paper and several
boxes as if he could see everything clearly. A researcher shadowed him
in case he stumbled.

“You just had to see it to believe it,” said Beatrice de Gelder, a neuroscientist at Harvard
and Tilburg University in the Netherlands, who with an international
team of brain researchers reported on the patient on Monday in the
journal Current Biology. A video is online at www.beatricedegelder.com/books.html.

The
study, which included extensive brain imaging, is the most dramatic
demonstration to date of so-called blindsight, the native ability to
sense things using the brain’s primitive, subcortical — and
entirely subconscious — visual system.