I hear a story about a behavioral experiment that was conducted in a lab:
There is a dog in a cage. Scientists rig one side of the cage so that every time the dog goes to that side of the cage she will get an electrical shock.
Soon enough, the dog learns to stay on the other side of the cage.
Within a few weeks, the scientists re-wire the cage so that she’ll get shocked on the side she was conditioned to stay on pain-free. As predicted, the dog learns to lay down on the opposite, formerly electrified side of the cage.