The idea of the experiment was to condition dogs to associate a high-pitched sound with fear. After hearing a loud sound, the dogs would receive mild but noticeable electric shocks. The expectation was that over time, the dogs would react to the sound as they did to the electric shock—by jumping out of the box and fleeing.

However, the dogs didn’t behave this way! Instead of taking the simplest action (jumping out of the box), they lay down on the floor and whined, making no attempt to avoid the discomfort.

Seligman theorized that this behavior could be because the dogs lacked the physical ability to avoid the shocks during the experiment—they had become accustomed to the inescapability of the shocks and learned helplessness.