Lunchtime doubly so

hourglassA powerfully engaging essay on the nature of mind and the perception of time over on Edge by David M. Eagleman:

Try this exercise: Put this book down [or just stop reading the screen] and go look in a mirror. Now move your eyes back and forth, so that you’re looking at your left eye, then at your right eye, then at your left eye again. When your eyes shift from one position to the other, they take time to move and land on the other location. But here’s the kicker: you never see your eyes move. What is happening to the time gaps during which your eyes are moving? Why do you feel as though there is no break in time while you’re changing your eye position? (Remember that it’s easy to detect someone else’s eyes moving, so the answer cannot be that eye movements are too fast to see.)

Not only does our perception of time vary under different conditions, different sensory inputs do not slow down to the same subjective time:

Duration distortions are not the same as a unified time slowing down, as it does in movies. Like vision, time perception is underpinned by a collaboration of separate neural mechanisms that usually work in concert but can be teased apart under the right circumstances.

This is a fascinating and SF-mineworthy area of research.

[image from bogenfreund on flickr]

4 thoughts on “Lunchtime doubly so”

  1. Perhaps I’m missing something more philosophical or metaphorical in the above example, but from a directly literal and physical point of view, the reason you don’t see your eyes moving in the mirror is that you are only looking directly at them when they are not in motion! You are looking in a mirror, remember? So there are only 2 positions that correspond to you looking directly at an eye, not a continuum of positions. If you want to actually watch a pair of eyes moving continuously, either watch somebody else’s eyes or take a video your face. Then its no problem! Or, if you prefer, keep your eyes fixed on your image in the mirror and rotate your head instead. You can certainly see your eyes turning (relative to your head) when you do that! In summary, being able to observe your own eye motions (or not) is more a consequence of optics than of the perception of time. Now, with that said, I do believe that there are many interesting questions about how people perceive the passage of time. But how my eyes appear to move (or not) in the mirror doesn’t seem strange at all to me.

  2. Blindsight used saccadic masking as a major plot point, so the topic has been explored in scifi before.

  3. Anonymous was right to mention Saccadic masking, which is an interesting phenomenon. (See
    That clearly applies to our customary quick eye motions (i.e., shifting one’s view from one discrete place to another). If we return to the mirror example, imagine keeping your head fixed, but having the mirror swival (orbit) smoothly around your head in arcs, with its perpendicular always directed at the point between your eyes, while you allow your eyes to track your image in the mirror. In that case, your eyes will rotate smoothly (or nearly so) and you will be able to see your eyes turning. So in that configuration, you CAN see your eyes moving in a mirror, even with your head held fixed. So with the mirror, it is all about optics.

  4. Only slightly related, but my favourite thing about webcams is that they have just enough of a timelag for me to watch myself blink.

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