Human brain predicts the future
Returning one of British tennis ace Andy Murray's 140mph serves requires clairvoyance as well as skill, research has shown.
Only by predicting the future are you going to stand any chance of hitting the ball back. Yet this is a feat routinely accomplished by the brain when faced with fast-moving objects, a study has found.
Whether it be an on-coming tennis or cricket ball, a striking fist, or a car, the brain looks ahead of time. To compensate for delays in neural processing, it "sees" the object not where it is, but where it will be a fraction of a second later.
Since it can take a tenth of a second for the brain to process visual images, this ability to perceive the future is vital to everyday life. Without it, a ball or other object moving at 120 mph will have already advanced 15 feet before its position is registered.
Even at slower speeds the brain's visual processing latency would lead to a myriad mistakes in timing and co-ordination.
Scientists studied the phenomenon by conducting brain scans of six volunteers as they watched flashes appear on a moving background. An illusion was created of the flashes shifting in the direction of motion, thereby engaging the brain's prediction mechanism.
The functional magnetic resonance imaging (fMRI) scans showed that flashes perceived in advance produced the same brain activity patterns as those in the same real-time locations against a still background.
In both cases the images were processed in a region of the brain's visual cortex known as V5.
"For the first time, we can see this sophisticated prediction mechanism at work in the human brain," said psychologist Dr Gerrit Maus, from the University of California at Berkeley, US, who led the study published in the journal Neuron.
The research could help towards better diagnosis and treatment of many disorders involving motion perception, say the scientists. People with an impaired ability to perceive motion cannot perform tasks as simple as pouring a cup of coffee or crossing the road, they pointed out.