Less is more for smart perception

Brains of high-IQ people automatically ignore the least relevant sights

People with high IQs see the world in their own way. Their brains seamlessly separate the visual wheat from the chaff, allowing them to home in on the most relevant information, a new study finds.

Using a simple visual exercise, a team led by psychologist Duje Tadin of the University of Rochester in New York found that high-IQ volunteers excelled at detecting the direction in which small objects moved but struggled at tracking large moving objects.

That’s a useful trait, the scientists report May 23 in Current Biology. In many situations, small moving objects in the foreground are more important to track than background activity. But whether people are driving a car, walking down a street or writing on a computer in an open workspace, their visual field includes humans and objects in the background that are in constant motion.

Among participants in the new study, the lower the IQ, the less able a person was to spot movements of small objects, but the better able to monitor large objects.

Both perception and intelligence thrive on an involuntary neural knack for detecting relevant information and filtering out the rest, Tadin says. “It’s not a conscious strategy but something automatic and fundamentally different about the way the brains of high-IQ individuals work.”

The new findings fit with evidence gathered over the past 25 years that the brains of people with high IQs and expertise in particular activities work more efficiently than other people’s brains, says psychologist and intelligence researcher Richard Haier of the University of California, Irvine. “More does not necessarily mean better when it comes to brain processing,” he says.

Tadin’s group asked 65 volunteers, with IQs ranging from around 80 to 140, to watch videos in which moving black and white bars repeatedly flashed on the screen. The goal was to identify, as quickly as possible, whether the bars were moving right or left. The bars appeared in three sizes, with the smallest version shown in a central circle where human motion perception is known to be especially good.

Volunteers had no chance to decide consciously whether to focus on bars of particular sizes, Tadin says. Random presentations of rapidly flashed bars of different sizes forced the brain to track movements unconsciously.

Researchers have long reported a modest tendency of high-IQ individuals to perform well on simple visual and other sensory tasks. In Tadin’s study, conducting separate tests with small and large moving objects produced much stronger associations with IQ.