It’s about time for this post. Or, actually, this post is about time. I’ve been spending a lot of my own time absorbed in watching the London Olympics. A lot of the drama comes down to time. And how time spans the thin margin of victory that often plays out.
A good case in point is the women’s triathlon. Switzerland’s Nicola Spirig won gold while Lisa Norden of Sweden captured silver. But if you were watching the race in real time you would not have known who won. It was an actual “photo-finish” that required several views to confirm the outcome. That’s because you couldn’t really see a difference unless you looked very carefully with special equipment.
A couple of thoughts come to mind here. What does it mean when we cannot discern the results ourselves? Most events we deal with in daily life can be recognized for what they are or at least how they seem to unfold. In the case of the 2012 Olympic Triathlon, the timing said both the Swiss and Swedish runners were “0.00” relative to each other. Only careful perusal of the photographs revealed who “finished first”.
How we perceive the visual timing of physical events—and also the timing of auditory events like tempo in music—is highly subjective. We’ve all had an experience of this. It’s the basis for the expression “a watched pot never boils” and “time flies when you’re having fun”.
It’s also part of a bizarre experience you can have when looking at an analogue clock or watch. Sometimes when you glance at the clockface, the second hand appears to freeze. Enter the stopped clock illusion. Or, if you want to get all scienc-ey, a good example of chronostasis.
Chronostasis describes the illusion of time seemingly “extending” or “stretching” or seeming to move “backward” when we make a rapid eye movement—a saccade—towards some object. Even though your perception seems to be smooth, when you scan a visual scene your eyes are really taking rapid jumps. And I mean rapid.
A saccade can be as fast as 900 degrees per second and is the fastest movement you can make. They are also very short with a range of ~20-200 milliseconds depending on the “jump needed”. When you are reading this right now your saccades are about 20-30 milliseconds long.
Because of all this your brain has to do some pretty fancy processing in order to make sense of all that you are “seeing”. The visual information coming from your optic nerves has to be integrated in the brain and contextualized with the overall perception of what is going on.
Your brain is busy trying to make sure you think things in the environment around you are moving very smoothly. In the case of vision, the movement of your actual sensors—your eyes and the retinal cells in them—introduces lots of problems. And trying to correct for those problems creates some of these illusions.
The change in perception of time is what makes that second hand on a clock or watch appear to stop. This compensation in your brain is in fact going on all the time. It’s just much more noticeable when we view an external object that has its own internal timer that moves at a steady rate. Like a clock or watch.
Since some things that are in fact moving may appear to be stopped, the flipside of this whole thing is to think about the times we think we see something moving when it is in fact stopped. Does the way our brains work to kind of fit together events in a post-hoc way apply here too?
When it comes to events based on time and motion (pick any sport really) timing is down to subjectivity.
Of course there’s another aspect to this that I’ll take on in a future post. Is it really a first place finish if we cannot even notice it? Other events in different sports—like downhill skiing—can be decided by a few hundredths of a second. Can we human beings even determine what that is?
The take home here is that the next time you are watching something at a big sports event like the Olympics or your daughter’s softball game (out at first, or not?), keep this in mind—seeing is believing, but we can’t always believe what we think we see.
© E. Paul Zehr, 2012