Thursday, July 21, 2011

Chasing Time

Stopped clock illusion

The stopped clock illusion is a weird effect that you may have experienced. It happens when you look at an analogue watch and the second-hand seems to freeze for longer than a second before moving on.
I always thought this was because I just happened to look at it right at the start of the second, but this is actually an illusion.
What is happening is that when your eyes move from one point to another (a saccade), your perception of time stretches slightly (Yarrow et al., 2001). Weirdly, it stretches backwards. So your brain tells you that you've been looking at the watch for slightly longer than you really have. Hence the illusion that the second-hand is frozen for more than a second.
This happens every time our eyes move from one fixation point to the next, it's just that we only notice it when looking at a watch. One explanation is that our brains are filling in the gap while our eyes move from looking at one thing to the next.

Life- Threatening Situations 

People often report that time seems to slow down in life-threatening situations, like skydiving.

But are we really processing more information in these seconds when time seems to stretch? Is it like slow-motion cameras in sports which can actually see more details of the high-speed action?

To test this, Stetson et al. (2007) had people staring at a special chronometer while free-falling 50 metres into a net. What they found was that time resolution doesn't increase: we're not able to distinguish shorter periods of time when in danger. What happens is we remember the time as longer because we record more of the experience. Life-threatening experiences make us really pay attention but we don't gain superhuman powers of perception.

Time is relative

The last words on time come from two great thinkers; first Albert Einstein:
"Put your hand on a hot stove for a minute, and it seems like an hour. Sit with a pretty girl for an hour, and it seems like a minute. That's relativity."
And finally, Douglas Adams:
"Time is an illusion. Lunchtime doubly so."

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