London, Jan 30 (Agencies): An Indian-origin researcher-led study has claimed that people with busy lives don't necessarily live longer, but they might feel as if they do.

Indian origin researcher Maneesh Sahani and his colleagues at University College London have ascertained that our brains use the world around us to keep track of time, and the more there is going on, the slower time feels, the 'New Scientist' reported.

Brains were thought to measure time by using some kind of internal clock that generates events at a relatively regular rate.

To test whether external stimuli might also play a role in our ability to process time, they showed 20 subjects a video of either a randomly changing stimulus --statistically modelled on the way that things naturally change randomly in the world around us -- or a static image, for a set period of time.

When asked to judge how much time had passed, subjects who'd been shown the moving stimulus were significantly more accurate. The volunteers were also shown the video at two different speeds and asked to rate the duration of each clip.

They thought both clips lasted the same amount of time, even though the faster version was shorter. The results suggest that the brain exploits changes in visual information, when it's available, to judge time, said Sahani.

The findings have been published in the latest edition
of the 'Current Biology' journal.