When someone tosses a ball at you and you don’t catch it, what happens in your brain? The brain predicts eye movements so the world around you appears stable. According to scientific consensus, we miss the ball when the prediction does not match the reality. However, a new study by PhD candidate Joreon Atsma at Donders Institute of Radboud University in the Netherlands offers evidence that the brain’s visual predictions may not be to blame for a lack of coordination. The findings challenge existing knowledge about brain-eye coordination and could help clinicians understand why some people seem to have trouble mastering physical coordination.

The study’s subjects participated in a computer-based exercise while their eye movements were monitored with an eye-tracking device. The subjects watched a computer screen on which a small ball appeared at random locations. At the end of the exercise, there was one last ball on the screen followed by a short flash of light nearby. Afterwards, the subject used the mouse to indicate where the flash of light was on the screen. Some subjects did not actually see the last ball because the flash appeared a moment sooner. This created a situation in which the brain’s predictions for the eyes would be incorrect.

The findings suggest that theories about brain-eye coordination are wrong. None of the participants made mistakes locating the flash of light, even when they had only a brief warning to not look at the ball.

“This demonstrates you don’t make localization errors solely on the basis of predictions. So far, literature has pretty much suggested the opposite. That is why we repeated the experiment several times to be sure,” explained Atsma.

These results may help understand why some people, like people on the autism spectrum, have problems with hand-eye coordination.

This research is published in the Journal of Neuroscience.

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