The first light is still fully visible
when the second flashes, and it cannot be noticed that the second comes
later than the first. If now in the same short time interval the first
light moves toward the second point, we should expect that we would see
the whole process as a lighted line at rest, inasmuch as the beginning
and the end point appear simultaneous, if the end is reached less than a
twentieth of a second after the starting point. But the experiment shows
the opposite result. Instead of the expected lighted line, we see in
this case an actual movement from one point to the other. Again we must
conclude that the movement is more than the mere seeing of successive
positions, as in this case we see the movement, while the isolated
positions do not appear as successive but as simultaneous.
Another group of interesting phenomena of movement may be formed from
those cases in which the moving object is more easily noticed than the
impressions of the whole field through which the movement is carried
out. We may overlook an area in our visual field, especially when it
lies far to one side from our fixation point, but as soon as anything
moves in that area our attention is drawn. We notice the movement more
quickly than the whole background in which the movement is executed. The
fluttering of kerchiefs at a far distance or the waving of flags for
signaling is characteristic.
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