Has it ever happened that you are in the middle of some serious work and suddenly your eyes look up to the clock on the wall and you find the second hand of the clock to be still, as if it has just taken a break in a moment of laziness? And after this moment, the clock ticks normally and the time restarts.

If yes, you do not have to worry and think too much about it. It is a normal experience that the psychologists name the stopped clock illusion. An ingenious experiment from a team at University College London recreated the experience in the lab by asking the volunteers to look away and then suddenly shift their gaze to a digital counter. When the subjects tried to judge how long they had been looking at the digit that first appeared, they systematically assumed it had been on for longer than it had. In this manner, the team managed to connect the experience of the stopped clock to the action of the person experiencing it. The explanation is as follows:

The action of moving our eyes from one point to another is extremely quick that most of us do not pay heed to what we are doing. But there is a momentary break in visual experience when you move your eyes from one point to another. Suppose, you stretch your arms out and move your eyes between the two index fingers and as you flick your eyes from left to right you will be able to detect an almost invisibly brief flash of darkness as input from your eyes is cut off. This brief interruption in your consciousness causes the stopped clock illusion.

The theory lies in the fact that our brains tend to build stories about the world from the ongoing input of our senses. The break in information caused by the rapid eye movement need to be covered up, thus the brain fills this gap with whatever comes after the break. The UCL team also showed that the longer the eye movements, longer are the pauses in the stopped clock. Normally this subterfuge is undetectable, but if move your eyes to something that is moving with precise regularity, a clock for instance, you will spot this pause in the form of an extra long second.

For better understanding, you may check this video by Vsauce(youtube channel)

Such illusions are created by a shift of attention. One is the dead phone illusion where in you pick up an old-fashioned phone and catch an initial pause between the dial tone that seems to last longer than the others. These illusions depict that something as simple as the time passing experience is constructed by our brains. Like with everything else, what we experience is our brain’s best guess about the world. We are all time travelers, in the sense that we don’t ever get to know time directly.
[source: www.bbc.com]