London - Flies avoid being swatted in the same way that Keanu Reeves dodges bullets in the film The Matrix – by watching time pass slowly.
To the insect, that rolled-up newspaper moving at lightning speed might as well be inching through thick treacle.
Like Reeves side-stepping slow motion bullets, the fly has ample time to escape.
Of course, time is really passing at the same speed. But the fly’s eyes send updates to its brain far more frequently than a human’s eyes, and its mental processes are similarly much more rapid than ours.
The result is that a fly sees objects moving slowly in comparison to its own rapid reactions. It makes a decision and buzzes away from danger far more quickly than a human can follow it with a newspaper.
Flies are not the only species to perceive time differently. Research suggests that time perception is related to size.
Generally the smaller an animal is, the faster its brain works, so outside events appear to be happening slowly.
Scientists worked this out by flashing a light in rapid flickers in front of animals. If the flashes are close enough together, an observer sees them as a continuous blur.
But researchers found that the flicker speed at which flashes seemed to merge together was different for different species.
“A lot of researchers have looked at this in different animals,” said Dr Andrew Jackson of Trinity College Dublin.
“Interestingly, there’s a large difference between big and small species. Animals smaller than us see the world in slo-mo.
“If you look at flies, they can perceive light flickering up to four times faster than we can. You can imagine a fly literally seeing everything in slow motion.”
More than 30 species were studied, including rodents, eels, lizards, chickens, pigeons, dogs, and leatherback turtles – big creatures for whom time passes relatively rapidly.
Professor Graeme Ruxton, of the University of St Andrews, said: “This work highlights the impressive capabilities of even the smallest animal brains.” - Daily Mail