May 8, 2013
Swing, Batter: Understanding Speed
Michael Harper for redOrbit.com — Your Universe Online
Researchers from the University of California in Berkeley have finally pinpointed the area of the brain responsible for not only seeing fast-moving objects, but responding to them as well. This development explains why athletes are able to react and respond to balls traveling at speeds upwards of 100 miles an hour. According to this research, our brains are capable of “pushing” fast moving objects, so we perceive them to be farther along in their trajectory than they actually are. Without this, Gerrit Maus, a postdoctoral fellow in psychology at UC Berkeley and lead author of this study, says our brains couldn´t react fast enough in real time to hit a 95-mile an hour fastball.
Without this pushing, it could take the brain up to one-tenth of a second to fully process the trajectory of a quickly moving object. When viewed in the context of an object traveling at 120 miles per hour, one-tenth of a second is equivalent to 15 feet. According to the researchers, we would constantly be hit by balls and other fast moving objects if our brains weren´t able to properly process these flying projectiles.
It is Maus´ hope this new understanding of the brain´s operations could help doctors diagnose and treat other brain disorders, particularly those that inhibit motion perception. Those who cannot perceive motion are unable to locate moving objects and even have difficulty performing the simplest of tasks, such as pouring a cup of tea.
To find this function, Maus and team employed a functional Magnetic Resonance Imaging machine (fMRI) to observe the visual cortex of the brain. This area is responsible for overcoming the general sluggishness of our brains in processing images. The middle temporal region of this cortex specifically, known as V5, works as the engine of this process, computing where objects are likely to end up once they lose their momentum.
Sitting six volunteers next to the fMRI machine, the researchers ran a “flash-drag effect” test. This is a two-part visual illusion that displays two objects, such as two squares, in line with one another on a plane. The background then begins to move as the bottom object begins to flash. As the background moves back and forth, the second flashing object appears to be out of line with the first, top object.
“The brain interprets the flashes as part of the moving background, and therefore engages its prediction mechanism to compensate for processing delays,” said Maus.
In an earlier paper published by Maus, he discovered the V5 region of the brain is the most likely spot for this motion prediction to occur.
“Now not only can we see the outcome of prediction in area V5,” Maus said, “But we can also show that it is causally involved in enabling us to see objects accurately in predicted positions.”
Of course, when the V5 works properly and predicts the object´s trajectory, our brains are actually lying to us, or showing us something that isn´t yet true. Maus says, however, the brain´s ability to do this is actually necessary for our evolutionary survival.
"The image that hits the eye and then is processed by the brain is not in sync with the real world, but the brain is clever enough to compensate for that,” Maus said. “What we perceive doesn´t necessarily have that much to do with the real world, but it is what we need to know to interact with the real world.”