The mystery of how attention improves the perception of incoming sensory stimulation has been a long-time concern of scientists. One hypothesis is that when you pay attention neurons produce stronger brain activity, as if the stimulus itself was stronger. That would mean that paying attention might make something appear more intense, and possibly distort its actual appearance.
In the Northwestern study, EEG measures of brain activity were used to show precisely how attention alters brain activity. The team of psychologists and neuroscientists used a new strategy for understanding the mechanisms whereby sustained attention makes us process things more effectively, literally making the world come into sharper focus.
"When you pay attention cells aren't only responding more strongly to stimuli," said co-author Marcia Grabowecky, research assistant professor of psychology in Northwestern's Weinberg College of Arts and Sciences. "Rather a population of cells is responding more coherently. It is almost like a conductor stepping in to control a large set of unruly musicians in an orchestra so that they all play together. Cells synchronize precisely to the conductor's cues."
The article, "Attention Induces Synchronization-Based Response Gain in Steady-State Visual Evoked Potentials," will be published in Nature Neuroscience. It was published Dec. 17 in advance of the print version on Advance Online Publication (AOP) on Nature Neuroscience's Web site.
Each participant in the study wore a cap with 64 electrodes to record their brain waves. The brain waves fluctuated in sync with flickering stimuli that appeared on a computer screen. At any given time, two target patterns were shown, but subjects