Where is the flash? The flash-lag effect
Keep your eyes on the red dot. A white bar rotates around it. Every couple of seconds two yellow lines flash exactly in line with the bar. Do they look in line?
Bar keeps moving. Most people see the flash behind the bar. Signals from the eye need tens of milliseconds to reach visual cortex, so a moving object should always be seen a little in the past. One explanation (Nijhawan, 1994) is that the visual system extrapolates: it pushes moving objects forward to where they probably are now. A sudden flash cannot be predicted, so it is not pushed forward.
Bar stops at flash. Now the lag largely disappears. If the brain always extrapolates, why don't we see the bar overshoot its last position? One answer: the abrupt stop sends a strong "something changed" signal that overrides the prediction. Shi and Nijhawan (2012) tested this idea in the centre of the eye, where certain stimuli cannot produce such a signal. See the foveal extrapolation demo.
Nijhawan, R. (1994). Motion extrapolation in catching. Nature, 370, 256–257. · Shi, Z., & Nijhawan, R. (2012). Motion extrapolation in the central fovea. PLoS ONE, 7(3), e33651.