In 1688, Irish scientist William Molyneux asked philosopher John Locke "if a man born blind can feel the differences between shapes such as spheres and cubes, could he similarly distinguish those objects by sight if given the ability to see?"That philosophical thought experiment, called Molyneux's Problem, stood for centuries until MIT researchers Richard Held and Pawan Sinha collaborated with Indian surgeons to operate to restore sight in children who'd been blind from curable causes:
Held, Sinha, and colleagues recruited five children, ages 8 to 17, from Project Prakash to tackle Molyneux's question. The researchers built 20 pairs of simple shapes from toy blocks and tested the children within 48 hours of the surgery to restore their sight. The children had not encountered these unusual shapes before. [...] After feeling a shape, the children did only slightly better than chance at identifying it by sight alone, the team reports online today in Nature Neuroscience.
That result suggests a negative answer to Molyneux's question. Because many children travel long distances for the operations, most go home with their families before the researchers can do follow-up experiments, Sinha says. However, when the researchers retested two of the boys with a new set of shapes a few days later, their accuracy on the touch-to-vision experiment jumped to above 80%. That suggests a more nuanced answer of "initially no but subsequently yes," Sinha says.
"It's a great story," says Alvaro Pascual-Leone, a neurologist and neuroscientist at Harvard Medical School in Boston. The change in the children's ability to integrate touch and vision happens too fast to be explained by major rewiring in the brain, Pascual-Leone says. Even though they grew up recognizing objects by touch, they needed only a little bit of visual experience to learn to translate between the two senses. "They're not starting from zero," he says.
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