Q. Why is it so hard to swat a housefly? A. It sees you coming in slow motion

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Trying to swat a fly is like trying to shoot Keanu Reeves in The Matrix because time appears to move more slowly in the minds of smaller animals, a new study has claimed.

The ultra-nimble fly is capable of processing nearly seven times as much information in a second as a human. This means a rolled-up piece of newspaper that is moving so fast that it appears as a blur to our eyes is, to the fly, more like the slow-motion bullets that are easily dodged by Neo, Reeves’ character in The Matrix.

A paper published in Animal Behaviour journal today found the perception of time was linked to the size of an animal’s body and metabolic rate.

But it can also change depending on the circumstances: time appears to slow down during stressful situations like a car crash because in an attempt to avoid disaster, the brain increases the amount of information it is taking in.

Dogs are able to process information at twice the rate of humans and so tend not to be interested in television. All they see is a flickering image, as if a projector had broken and the film slowed.

The scientists used the point at which a flickering light appears as a solid beam as a way to examine how different animals perceive time.

Houseflies can see a light flickering at a rate nearly seven times faster than we can. “That’s because they are getting much more information per second through their visual system… so that second feels longer,” one of the researchers, Dr Luke McNally, of Edinburgh University, said. “These animals are perceiving the world in a very, very different way.”

This explains why flies seem so hard to hit. “[For the fly] it feels like you are moving so slowly towards them. It’s the same as the famous bullet-time scene where the bullets are moving at this incredibly slow rate as far as Keanu is concerned,” Dr McNally said.

At the other end of the scale, time rushes by for the slow-moving leatherback turtle because it gets only about a third of the amount of information that humans do in a second. “This perception of time co-evolved with how fast you can move, how fast your metabolism is and how small you are,” Dr McNally said. “There’s very little point in gaining all this information if you cannot react to it.”

However, there is at least one animal whose perception of time is at odds with its physical characteristics.

“Tiger beetles can run faster than their eyes can keep up,” Dr McNally said. “They run towards their prey, then they have to stop, and then sprint again and hope they’ll hit into it.”

Dr Andrew Jackson, from Trinity College Dublin, who led the study, said the effect may also account for the way time seems to speed up as we get older: “It’s tempting to think that for children time moves more slowly than it does for grown ups, and there is some evidence that it might.”