You know the exit is somewhere along this stretch of highway, but you have never taken it before and do not want to miss it. As you carefully scan the side of the road for the exit sign, numerous distractions intrude on your visual field: billboards, a snazzy convertible, a cell phone buzzing on the dashboard. How does your brain focus on the task at hand?
To answer this question, neuroscientists generally study the way the brain strengthens its response to what you are looking for—jolting itself with an especially large electrical pulse when you see it. Another mental trick may be just as important, according to a study published in April in the Journal of Neuroscience: the brain deliberately weakens its reaction to everything else so that the target seems more important in comparison.
Cognitive neuroscientists John Gaspar and John McDonald, both at Simon Fraser University in British Columbia, arrived at the conclusion after asking 48 college students to take attention tests on a computer. The volunteers had to quickly spot a lone yellow circle among an array of green circles without being distracted by an even more eye-catching red circle. All the while the researchers monitored electrical activity in the students' brains using a net of electrodes attached to their scalps. The recorded patterns revealed that their brains consistently suppressed reactions to all circles except the one they were looking for—the first direct evidence of this particular neural process in action.
“Neuroscientists have known about suppression for quite some time, but it's not given as much thought as mechanisms that boost attention,” McDonald says. “We have nailed down how you can prevent distraction through suppression.” Such research may eventually help scientists understand what is happening in the brains of people with attention problems, such as attention-deficit/hyperactivity disorder. And in a world increasingly permeated by distractions—a major contributor to traffic accidents—any insights into how the brain pays attention should get ours.