Early View on Apparent Motion

The movement we see on computers, televisions, and even motion pictures, is all illusory. The screens don’t move; pixels don’t move. But, if a pattern of illumination is shifted from one locale to another, with the appropriate time interval between the separate illuminations, we see the shift as a movement. We are going to cover apparent motion in our “Vision in Motion” module. Like other parts of the new module, this hasn’t been completed yet. However, you can play around with an early draft of our applet to illustrate apparent motion.

Apparent motion only occurs within a limited range of frequencies and distances. If you slow down or speed up the motion sufficiently, the motion no longer appears fluid. Instead, we notice the discrete shifts. This is particulary true as the distance between our “lamps” increases. You may be able to make the apparent motion disappear simply by fixating on a single column of lamps and noting it never moves. Of course, the smaller the lamps, and the closer together they are, the more seamless the motion appears.