14 DAY TRIAL // Scientists were recently able to answer a centuries-old question, which sought to clear up an interesting thought experiment created by philosophers. They were wondering whether a person who was blind but recovered sight is able to distinguish visually between objects.
The idea was that the formerly-blind person would be presented with objects that they could previously distinguish through the sense of touch. What experts wanted to know was whether they could create the same mental associations when they gained the ability to see.
But testing such an idea proved to be impossible for hundreds of years. It wasn't until the development of modern scientific investigation techniques that an accurate experiment became possible.
Since philosophers first wondered about the effects of sight in this regard, “this has been one of the foremost questions in the philosophy of mind,” explains Pawan Sinha, a professor with the Massachusetts Institute of Technology (MIT) Department of Brain and Cognitive Sciences (BCS).
He conducted an investigation on children and adolescents in India, who regained their sight in late childhood or even later. At first, after they had completed eye surgery and began to see, the test subjects were unable to correlate what they felt with what they saw.
However, the trait was quickly acquired within days of the operation. This has the tremendous implication that the brain is not capable of correlating sensory input from birth. This ability is not innate, but rather acquired shortly after birth.
Sinha was the leader of the new study, the participants were selected from Project Prakash. This is an initiative the MIT expert set up to treat Indian children with curable forms of blindness. At the same time, he used this opportunity to investigate how visual inputs are processed in the brain.
“These children have been treated and their lives have hopefully been improved, and that has also allowed us to answer a question that scientists have been puzzling about for over three centuries,” the expert says.
Touch-to-vision tests that the team applied to children who had completed surgery showed a lack of correlation between visual and touch stimuli in the brain. These were the results of readings taken 48 hours after the surgery.
When the same tests were applied a week later, the children scored considerably higher on the tests, demonstrating that their brains had already learned the new ability.