Standing Out in a Crowd: What Gets Attention
Scanning, Sifting for What Matters Most Starts in the Brain
April 21, 2005 -- Ever search for someone in a crowded room, scan the supermarket shelves for your favorite spaghetti sauce, survey your laundry for the proverbial missing sock, or pick through a bag of Halloween candy to find your favorite chocolate bar?
Then you know what it's like to hunt through a field of almost-but-not-quite contenders to find what you're really looking for.
New research shows how some items stand out from the pack. It's as if your brain quickly highlights what matters, glossing over what's irrelevant.
Raising the Stakes
We launch those kinds of searches a thousand times a day, says Jeremy Wolfe, PhD, in the journal Science. Wolfe is an ophthalmology professor and head of Harvard Medical School's Visual Attention Lab.
Most of the time, those tasks might seem routine, such as looking for a corkscrew in the kitchen gadget drawer, says Wolfe. But you might be surprised at the mental hoops your brain goes through to pull it off.
What's more, the stakes get considerably higher with some searches, like screening luggage at an airport or reviewing routine mammograms, says Wolfe.
Suddenly, it's not just a matter of momentary embarrassment from tapping the wrong person on the shoulder at a party. When big-time consequences are on the line, visual searches need all the help they can get.
Scientists gave monkeys a "Where is Waldo" type of test. The monkeys were trained to scan a bunch of colorful shapes to find the ones the researchers selected.
The monkeys first scanned all the objects looking for a key feature. That's called "parallel" searching, say the researchers, who included Narcisse Bichot, PhD, of the National Institute of Mental Health.
Then, the monkeys went one-by-one through those items to find the desired object ("serial" searching). Both searches were done in specific areas of the part of the monkeys' brains called the visual cortex, say Bichot and colleagues. The visual cortex is located in the back and lower parts of the brain.
Presumably, other primates (ourselves included) could follow the same pattern.
Here's how that might work for people.
Let's say you're in a crowded room, looking for a tall man with short, dark hair. First, you might look for all the tall people in the room (a parallel search) and then look at each tall person to find those with short, dark hair (a serial search) until you've found the right man.
Or, you might combine parallel and serial searches to find your favorite bits in a fruit salad, writes Wolfe, commenting on Bichot's findings.
"We eagerly await development of new ways to improve human performance on such tasks or the invention of machines that could take over or assist with them," writes Wolfe.
"Understanding how biological systems do so well at performing a range of search tasks should help us to improve the outcome of those artificial search tasks on which we, quite literally, stake our lives," he concludes.