The Second Hand Stops

Today I went out to buy a clock. The one I wanted was sold out, and I stood there wondering whether something else would do — but in the end I came home without one.

While I was looking at one of the clocks on display, its second hand seemed to stop. “Is the battery dead?” I thought for a moment, but as I kept watching, it started moving normally again.

Now that I think about it, this has happened to me now and then for a long time. You glance up at a wall clock, and for an instant the second hand freezes in place. Only that first second feels long — though of course the clock is keeping perfect time, exactly as it should. What stopped wasn’t the clock, but my perception. It bothered me, so I looked it up.

When the eye moves quickly from one place to another — during the rapid motion called a saccade — the brain briefly lowers the sensitivity of its visual input, to keep the blurred, shifting view from throwing perception into confusion. This is known as saccadic suppression.

And the moment your gaze lands on the clock face, the brain, filling in the blank it couldn’t see, is thought to reach back in time and stretch the image of what it landed on by a small amount. This is the phenomenon called chronostasis.

In short, you feel that stretched portion as extra length. This correction is happening even when you’re not looking at a clock — it goes on countless times in daily life. It’s only because the second hand gives us an exact reference that we can notice the correction at all.

That thing I’d experienced now and then since childhood — the second hand freezing for an instant — turns out to work like this.

Cameras and smartphones now come with image stabilization built in. Chronostasis in the brain, and the correction in a camera, are both systems that sense a wobble and go to work behind the scenes. We live receiving a shake-free image from both the brain and the machine. I’d been using the camera’s stabilization without a second thought, of course — but I had no idea there was one inside my own head too.