LH

 A

Humans aren’t the only creatures who get more stressed if they

don’t have control. As you’ll learn in this chapter, research with

rodents, dogs, monkeys, and other animals clearly demonstrates that

uncontrollable stress is more toxic to the brain, body, and behavior of

many species than controllable stress. In the classic “learned helpless-

ness” study (Seligman and Maier 1967), dogs were exposed either to

electric shocks they could terminate by pushing a lever (controllable

shock condition) or to electric shocks that began and ended indepen-

dently of the dogs’ behavior (uncontrollable shock condition).

Although both groups received the same overall amount of shock,

dogs that were exposed to uncontrollable shock acted more distressed.

Even more troubling, when the dogs were later put into a shuttle box

in which they could escape shock by jumping over a barrier, only those

previously exposed to controllable shock successfully learned the

escape response. Dogs who had been previously exposed to uncontrol-

lable shock did not learn to escape the shock. The researchers theo-

rized that the dogs in the uncontrollable shock condition had

previously learned that their behaviors could not prevent the aversive

consequences, so they gave up trying. Thus, they never learned that

conditions had changed and that escape was now within reach.

Professor Seligman believed that these problems in learning and moti-

vation were similar to those found in people with depression. He pro-

posed that depression is a form of “learned helplessness” caused by

uncontrollable stress in early life.

A