Why is it that most of us are able to track down the tiny sketch of a bespectacled cartoon man wearing a striped shirt and a funny hat—in the midst of a busy scene filled with distractions and look-alikes?
Finding "Waldo" might be a tad tamer than hunting down a prehistoric dinner. But we can do both because we're excellent visual hunters, and a new study demonstrates that the human brain uses its inputs and neural networks to find "search objects" at a near-optimal level.
"Surprisingly, even in a complex task like detecting an object in a scene with distracters, we find that people's performance is near optimal," Wei Ji Ma, an assistant professor of neuroscience at Baylor College of Medicine and co-author of the new study, said in a prepared statement. "That means that the brain manages to do the best possible job given the available information"—even when "many objects might look like a target for which you are searching."
We are not unique in the animal kingdom in fixating on a target image. Other visual hunters use this strategy, too. But what is impressive is the ways in which the oversized and convoluted human brain has streamlined its abilities, the researchers contend.
"Target detection involves integrating information from multiple locations," Ma said. "It is a cognitive judgment as well as a visual one," he said—"the brain has to weigh different pieces of visual information."
For the new study, subjects were asked to quickly find a line of a particular orientation on a computer screen that displayed a whole set of helter-skelter lines with different levels of visual contrast. Subjects had less than a second to make this judgment—and the target line didn't even appear on every screen.
"We found that even in this complex task, people came close to being optimal in detecting the target," Ma said. "The visual system is automatically and subconsciously doing complex tasks." Ma and his team suggest that in the hunt for the target line, people were using specific groups of neurons that are keyed into identifying that specific line orientation.
"Our eyes are the camera, but the process of interpreting the image in our brains is seeing," he said.
The new research was published online May 8 in Nature Neuroscience. (Scientific American is part of Nature Publishing Group.)
Image courtesy of iStockphoto/prill