New study shows that deaf people really do have enhanced sight

The idea that people who are denied one sense have their other senses enhanced has been called a myth. But it looks like that myth was a myth. A recent study showed that deaf people's eyes develop enhanced vision.

It's not surprising that people who rely on all their senses to get by are amazed by what people who lack one sense can do. It's tempting to say it takes superpowers to function without the use of what many people would consider necessary senses. Maybe that's where we got the often-repeated idea that people who lose one sense develop stronger senses to compensate.

No, countered the members of the scientific community. People with disabilities didn't develop supersenses. They just used the abilities they had to a degree that most people don't. They looked at all the visual cues in a situation, instead of just listening for sounds to explain what was happening. It wasn't a matter of mysticism, or the inherent fairness of the universe, or specialized physiology. It was a matter of practice.

Turns out, it's not entirely practice. It is a matter of physiology, and deaf people, at least, have supersenses. Scientists scanned the retinas of people who were either deaf since birth or had lost their hearing in very early childhood. They found that the retinal neurones in deaf people's eyes were distributed differently than they were in hearing people. Most people only really focus on what's in front of them. Although they can train themselves, or be trained by experience, to notice things in their peripheral vision, their eyes are set up to look straight ahead. The retinal neurones of deaf people were scattered to take in the furthest extremes of peripheral vision. Specifically, they were designed to take note of what happened in the direction of the person's ears. The actual set-up of the eye changed to take in more of the surrounding area than hearing people would, all in order to mimic the way eyes and ears work together to form a picture of the world.

Behind this physical change is probably some more of that boring, prosaic 'practice' that scientists keep droning on about. The neurones were only redistributed in people who had been deaf from a very early age. These children would have had to lean on their sense of sight as they developed. But while these kids could change their focus, they couldn't consciously change their physiology. Their body did that for them, giving them an actual physical difference from hearing people. And scoring one for a popular old wives' tale.

Via PLoS One