Question

When you stop at a railroad crossing at night, instead of correctly perceiving two red lights that flash alternately you may perceive a single red light that moves back and forth from left to right. this is an example of ________.?

Answer 1

I'm pretty sure that there should be an options to choose. Anyway, I've seen this question before and I know that this is an example of the phi phenomenon.

Answer 2

This is an example of the phi phenomenon. This is an optical illusion that occurs when a series of still images, in this case the flashing lights, are viewed in quick succession. This given the illusion of a continuous movement rather than discrete still images.