In 1966, psychologists Mark Seligman and Steve Maier conducted a series of experiments on dogs. Animals were placed in the cells pre-divided into three groups. The control group after a while released without causing any harm, the second group of animals was subjected to repeated electric shocks that could stop pressing the lever on the inside, and the third group of animals was subjected to a sudden shock current, which could not be prevented. As a result, the dog developed a so-called "learned helplessness" - a reaction to unpleasant stimuli, based on the conviction of helplessness in the outside world. Soon, the animals began to show signs of clinical depression. After a while, the dogs from the third group was released from the cells and planted in open-air cages, from which it was easy to escape. Dogs again subjected to an electric current, but none of them had not even thought about running away. Instead, they passively react to the pain, seeing it as inevitable. Dogs have learned for myself from the previous negative experiences that escape is impossible and never made any attempt to escape from the cell. Scientists have suggested that the human stress response is a lot like a dog, people become helpless after several failures, one after another. It is unclear, whether the cost of such a banal conclusion of suffering poor animals.