www.paulnixon.org

Perception

Really fascinating.

And I thought it was just me!

You can get a feel for this from the frozen-time illusion - the sensation that you sometimes get when you look at a clock and the second hand appears to freeze momentarily before tick-tocking back into action.

This happens because of saccades. To compensate for the temporary shut-down of vision, your brain makes a guess at what it would have seen, but it does so retrospectively. So the 100 or so milliseconds of blindness gets back-filled with the image that appears after the saccade is over. If your eyes happen to alight on the clock just after the second hand has moved, your brain assumes that the hand was in that location for the duration of the saccade too. The "second" then lasts about 10 per cent longer than normal, which is enough for you to notice.