Animal experiments by psychologists at the University of Pennsylvania had shown that after repeated failures, most animals conclude that a situation is hopeless and beyond their control.

宾夕法尼亚大学（University of Pennsylvania）的心理学家进行的动物实验表明，在多次失败之后，大多数动物都会作出这样的结论：情况已无可救药，超出了它们的控制范围。