Massachusetts Institute of Technology Professor Earl Miller said the research also showed that when a person focuses attention, the electrical activity in the two brain areas synchronizes and oscillates at different frequencies.

"Loud, flashy things like fire alarms automatically grab our attention," Miller said. "By contrast, we choose to pay attention to certain things we think are important. We found two different modes of brain operation related to each, and they seem to originate in different parts of the brain.

"Further," he added, "the automatic versus willful modes of attention seem to rely on two different frequency channels in the brain, suggesting the brain might communicate in different frequency bands for different types of signals.

"Our work suggests that we should target different parts of the brain to try to fix different types of attention deficits," Miller said.

The study appears in the March 30 issue of the journal Science.