Humans, when you train them, can be phenomenally good at pattern recognition. Our long history as the descendants of organisms who could spot a predator in dappled grass probably has something to do with it, but today, this ability makes all manner of things possible. For instance, people who have lost their vision, or never had any to begin with, can learn to echolocate, using the sound bouncing off of the world around them to navigate. This peculiar skill is of abiding interest to many scientists, who are curious as to how the brain spatially interprets information carried by sound. A group at Ludwig-Maximilians-Universitaet in Munich has now published the results of a small study in which they trained a blind person and 11 sighted people to use sound to deduce the size of a room, scanning their brains in the process.
For this experiment, the group created a digital version of a nearby church. If a subject lying in an MRI machine hummed or clicked their tongue or made any other sound, they would hear, through headphones, a simulation of the echoes made by that noise in the church. At first, in a heavily padded room with almost no echoes of its own, the researchers trained their subjects to tell which of two generic computer-generated rooms was bigger using the sounds the rooms made, among other tasks. They were allowed to make whatever noises they wanted to elicit the echoes. Then, for the main experiment, the researchers had the subjects do the same with various versions of the church, which were shrunk or digitally enlarged to make rooms of different sizes, to see how close rooms could get in size before subjects stopped being able to tell the difference.