Brett Smith for redOrbit.com – Your Universe Online
Testing for intelligence can be a tricky proposition, with the tests themselves often being the product of cultural or intellectual biases.
Researchers from the University at Rochester believe they have found a simple, context-free visual test that can determine a person´s IQ regardless of cultural background, according to their report in the journal Current Biology.
“Because intelligence is such a broad construct, you can’t really track it back to one part of the brain,” said senior author Duje Tadin, an assistant professor of brain and cognitive sciences at the University of Rochester. “But since this task is so simple and so closely linked to IQ, it may give us clues about what makes a brain more efficient, and, consequently, more intelligent.”
The team began their work by asking volunteers to watch a series of videos showing black-and-white bars moving either left or right on a computer screen. The bars were shown in three sizes, from a thumb-sized central circle to an area about the size of an outstretched hand.
As the volunteers were asked to determine which direction the bars were moving, the researchers recorded how long it took the individual to correctly perceive the bars´ motion. Participants also took a standard intelligence test.
As they hypothesized, the researchers found that individuals with a high IQ were able pick up the movement of small objects faster than individuals with a low IQ.
“Being ‘quick witted’ and ‘quick on the draw’ generally go hand in hand,” said Michael Melnick, a doctoral candidate in brain and cognitive sciences at the University of Rochester.
However, when tests involved the larger images of moving bars, those with higher IQ scores were the slowest to respond.
“From previous research, we expected that all participants would be worse at detecting the movement of large images, but high IQ individuals were much, much worse,” Melnick said.
“There is something about the brains of high-IQ individuals that prevents them from quickly seeing large, background-like motions,” Tadin added.
According to the scientists, the inability to perceive large moving images is a marker for the brain’s ability to suppress background motion. In most scenarios, suppressing background movement is essential for processing visual information.
“We know from prior research which parts of the brain are involved in visual suppression of background motion,” said Tadin. “This new link to intelligence provides a good target for looking at what is different about the neural processing, what’s different about the neurochemistry, what’s different about the neurotransmitters of people with different IQs.”
The scientists stressed that their results were consistent, even after switching to a second set of volunteers and a more comprehensive IQ test. While the first set of experiments found a 64 percent correlation between background suppression and IQ, the larger and more comprehensive second set produced a 71 percent correlation.
“In our first experiment, the effect for motion was so strong,” recalls Tadin, “that I really thought this was a fluke.”
According to the researchers, the results show this vision test could remove some of the cultural limitations associated with standard IQ tests.
“Because the test is simple and non-verbal, it will also help researchers better understand neural processing in individuals with intellectual and developmental disabilities,” said co-author Loisa Bennetto, an associate professor of psychology at the University of Rochester.