Have you ever noticed that every time you first glance at a clock, that the second hand seems frozen in time, if just for an extended instant? It's as if you catch time off guard for a moment, fixed in some sort of surreal hiccup.

Well, you aren't alone. In fact, the experience is so common that scientists have a name for it: the Stopped Clock Illusion. Though you may be dismayed to discover that the experience is just an illusion (you don't have magical powers of time control), the mystery of why clocks seem to pause when we first glance at them is nevertheless a fascinating study into how our perception of time works.

Recently, scientists at University College London managed to recreate the stopped clock experience in a lab, finally unlocking the subtle intricacies of how our brains construct this bedazzling illusion, reports the BBC.

For the study, the researchers asked volunteers to look away and then suddenly shift their gazes to a digital counter. They then asked each volunteer to judge how long the moment seemed to last before the numbers on the clock changed. The volunteers systematically estimated the moment to last longer than the typical second. 

The trick, explained the researchers, comes from the act of suddenly shifting your gaze just before eyeing the clock. Rapid eye movements shift your gaze so swiftly that it creates a momentary break in the visual experience. Rather than blur your vision like with what happens when the camera shifts quickly in a movie, your brain instead attempts to build a seamless impression from the visual data. Thus, when your gaze shifts faster than you can process the visual experience, your brain makes up for the brief hiccup by extending the experience of what is seen when the eye movements settle.

Technically, this illusion happens every time you shift your attention rapidly, but usually it's not detectable. The reason we seem to catch our brains in the act when we look at a clock is because we also happen to know that clocks move with precise regularity independent of our perception.

Researchers also found that longer eye movements resulted in the experience of longer pauses in the clock, further supporting their thesis.

The study shows that how we experience the passage of time has as much to do with what's going on inside our heads as outside. But while the experience of time passing is not entirely something that happens to us, it's not all in our heads either. That is, no matter how often your eyes dart around rapidly, it's not going to halt the passage of time — not really. Unfortunately, the Stopped Clock Illusion is just an illusion; the insistent tick-tock of time still stops for no one.

Related on MNN: