How the Brain Makes Quick Decisions

Feb. 19, 2009 — -- It's the last set at Wimbledon and Serena Williams needs a little magic to take the match. Her opponent makes an amazing shot, but Williams somehow knows where the ball is going, and she's there. How could she have read her opponent's mind?

She didn't. But she may have been helped by a kind of human memory that scientists have been struggling to understand. Using her "implicit" memory, a short-term memory that people are not consciously aware they are using, Williams could have recognized her opponent's moves just before she hit that amazing shot, because she had seen the same moves a few minutes earlier when her opponent made a similar shot.

Of course, that's not the only thing that got Williams to the finals. Athleticism, conditioning, hard work and talent were the main reasons. But she had something else at work, and the rest of us use it all the time even if we don't know it. Sometimes, when we have to make a quick decision, we may think we're guessing, but we may be basing that "gut response" on real information, collected a few minutes earlier.

That's the implication of long-term research at Northwestern University in Evanston, Ill., by psychology professor Ken Paller and Joel L. Voss, who is now at the Beckman Institute, an interdisciplinary-research facility affiliated with the University of Illinois at Urbana-Champaign. Their research did not specifically involve athletics, but the results are consistent with work by other researchers who are studying how top athletes can make split-second decisions with very little information. How does a batter hit a fastball when he has to start swinging the bat before the ball even leaves the pitcher's hand? He relies on visual cues, even if he doesn't know it.

"Athletes learn to predict based on very little information," Paller said in a telephone interview.

In their most recent research, published in the journal Nature Neuroscience, Paller and Voss reveal a surprising discovery. Participants in that study were purposefully distracted while trying to quickly memorize visual patterns with their implicit memory and, quite surprisingly, did better when distracted than when they weren't.