Human Echolocation

We commonly think of bats and dolphins using echolocation to maneuver through obstacles and locate food, but are humans capable of this technique as well? One 15 year old boy, Benjamin Underwood, has learned to use echolocation as his primary means of navigation. Benjamin, who has two artificial eyes, makes clicking noises and uses the reverberations as his sight. He says that he can distinguish between the many echoes he hears and that helps him identify his surroundings. He can miraculously play basketball with his friends and ride his bike around the neighborhood with no problem, just using the clicks he makes to locate the hoop and other players on the court or curbs and traffic on the street. He can even play video games, knowing precisely which sounds correspond to certain events and rapidly reacting. Benjamin says every object in his life speaks to him in a way that no one else can hear or understand.

Another remarkable person, Kish, a 40 year old Californian, also uses clicking to identify his surroundings. Both Benjamin and Kish lost their eyes to cancer at the age of two, and were raised in encouraging environments, where they were told they could accomplish anything they desired. Maybe the combination of their age and family support is what led to the development of this incredible talent, but neither can recall when or how they began to hone this skill. Currently, Kish is teaching blind children the way he sees the world, and in doing so he is enabling them to be independent and resourceful.

Scientists have studied the brain activity of the blind, and have discovered some interesting findings. Using fMRI and PET scans, scientists have learned that the visual cortex is not deactivated in blind patients, as it was previously believed to be. It is actually very active and almost indistinguishable from the activity of sighted people during comparable tasks. Reading Braille has been the main focus of much research because while the blind read Braille their visual cortex are activated very similarly to sighted people reading print. Some believe that this activity plays no functional role in the brains of the blind, but most evidence contradicts that opinion. It is probable that blind people interpret these signals in different ways to generate images, just without the visual component. This is a hard concept to explain to sighted people, but Kish assures that he has “mental images that are very rich, very complex. They simply do not possess the visual element.”

Posted by: Nicole Eckart