Ever have this happen to you?
You're just pulling into a parking lot, you start to put your foot on the break and are coming to a stop...
At the same time a car (usually to the right of me), starts pulling out of the parking lot. You just catch it out of the corner of your eye..
Now your (or at least my) brain is confused, and thinks that my car is still moving forward, even though I am at a complete stop. Especially if you are parking near a building you may push the brake hard because you are worried for a second.
In the next second you realize what has happened, and maybe feel a little silly about it.
Whatever way you look at it, it's interesting how our brain interprets visual cues and makes assumptions which aren't always true.
More Optical Illusions...