Would a blind person, on regaining the ability to see, be able to immediately recognize an object by sight something previously known only by touch?
This question, posed by philosopher William Molyneux in 1688, may finally have been answered this week.
When (re)gaining their sight for the first time, congenitally blind children aren’t able to recognize something by sight if they've only ever touched it, a new study shows.
So in a sense (so to speak), we must learn to see. The ability is not innate: we have to learn that how objects look reflect how they feel.
Richard Held of MIT and colleagues studied a group of 5 children who are treated by Project Prakash, which treats curable blindness in parts of India where medical services are often inadequate. Study coauthor Pawan Sinha founded an organization in 2003.
The patients were ages 8 through 17, and they have all been blind from birth because of congenital cataracts or an opaque cornea (which should normally be transparent).
- First, they each had a cataract removal or received a corneal transplant.
- Within 48 hours of gaining sight, the patients were asked to feel a Lego-like brick.
- They were shown 2 different looking bricks, and then asked to match the brick they felt with one of them.
These patients were unable to correctly match the blocks they felt to what they only saw. Their average success rate was 58%. "They couldn't form the connection," says study coauthor Yuri Ostrovsky of MIT.
However, after they were retested 5 days later with no further training, some of these children showed a substantial improvement. Their accuracy was above 80%.
"Experience with the natural world was most likely responsible for the improvement," says Held.
So to answer the centuries old question: "initially no," Sinha says, “but subsequently yes.”
The study was published in Nature Neuroscience this week.
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