17 April 2011: PM Posts

Philosophical Question: can someone who used to be blind who suddenly got sight recognize shapes by sight? Well, no, not exactly, not right away. But…:

[...]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. In one experiment, the researchers gave the children a shape to feel (without looking), then asked them to feel two more shapes and indicate which was the same as the first one they’d felt. All five children chose the right shape more than 90% of the time. In a second experiment, the children could look but not touch. Again they nailed it. But on the third and most crucial experiment, their performance plummeted. 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.[...]

Paul Dirac: here is a nice BBC video about him and his equation:

And here is something that he discovered that we often teach to our differential equations class:

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