Ability to filter visual motion can predict IQ

Washington: Researchers at the University of Rochester have found that a simple visual task can predict IQ

This surprisingly simple exercise measures the brain`s unconscious ability to filter out visual movement. The study shows that individuals whose brains are better at automatically suppressing background motion perform better on standard measures of intelligence.

The test is the first purely sensory assessment to be strongly correlated with IQ and may provide a non-verbal and culturally unbiased tool for scientists seeking to understand neural processes associated with general intelligence.

"Because intelligence is such a broad construct, you can`t really track it back to one part of the brain," said Duje Tadin, a senior author on the study and 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," Tadin added.

In the study, individuals watched brief video clips of black and white bars moving across a computer screen. Their sole task was to identify which direction the bars drifted: to the right or to the left. The bars were presented in three sizes, with the smallest version restricted to the central circle where human motion perception is known to be optimal, an area roughly the width of the thumb when the hand is extended. Participants also took a standardized intelligence test.

As expected, people with higher IQ scores were faster at catching the movement of the bars when observing the smallest image. The results support prior research showing that individuals with higher IQs make simple perceptual judgments swifter and have faster reflexes.

But the tables turned when presented with the larger images. The higher a person`s IQ, the slower they were at detecting movement.

That counter-intuitive inability to perceive large moving images is a perceptual marker for the brain`s ability to suppress background motion, the authors explained.

The relationship between IQ and motion suppression points to the fundamental cognitive processes that underlie intelligence, the authors wrote.

The brain is bombarded by an overwhelming amount of sensory information, and its efficiency is built not only on how quickly our neural networks process these signals, but also on how good they are at suppressing less meaningful information.

"Rapid processing is of little utility unless it is restricted to the most relevant information," the authors concluded.

The researchers point out that this vision test could remove some of the limitations associated with standard IQ tests, which have been criticized for cultural bias.

The unexpected link between IQ and motion filtering was reported online in the Cell Press journal Current Biology .