Comments on: Lunchtime doubly so

By: Sarah Ennals

Sarah Ennals — Sun, 28 Jun 2009 12:18:22 +0000

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

By: Robert Koslover

Robert Koslover — Fri, 26 Jun 2009 01:18:49 +0000

Anonymous was right to mention Saccadic masking, which is an interesting phenomenon. (See http://en.wikipedia.org/wiki/Saccadic_masking)
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.

By: Anonymous

Anonymous — Fri, 26 Jun 2009 00:59:47 +0000

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

By: Robert Koslover

Robert Koslover — Fri, 26 Jun 2009 00:28:16 +0000

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.