Learned mastery in the rat
In a series of five experiments, we investigated the bidirectional effects of prior experience with both control or lack of control over shock on subsequent shock-motivated activity and escape learning. Rats were tested with inescapable shock rather than escapable shock as is used in typical helplessness experiments. Naive rats initially shuttled frequently during shock but decreased activity as testing continued. Pretraining with inescapable shock reduced shuttle responding throughout testing. Unexpectedly, rats which first learned to lever press to escape shock continued unabated shuttling through 200 trials of 10-sec duration inescapable shocks (Experiment 1). These bidirectional effects were replicated using a shuttle escape response for pretreatment and lever pressing as the test response. During two uninterrupted 1000-sec duration inescapable shocks (Experiment 2), escape rats continued to lever press through the 2000-sec of shock. In the third experiment, escapable shock facilitated and inescapable shock hindered later learning when the escape contingency was degraded by a 3-sec delay of shock termination. The fourth and fifth experiments demonstrated that (1) this associative facilitation effect is not simply due to an increase in active responding by escape animals (Experiment 4), and (2) no associative facilitation is observed if the contingency is not initially degraded by a 3-sec delay (Experiment 5). Taken together, these results are the first demonstration of bidirectional effects of control on aversively motivated behavior in animals. In addition to typical helplessness effects, a “mastery” phenomenon is observed. This mastery induced by experience with escape learning is characterized by (1) a motivational effect: persistent general active behavior in the face of inescapable shock, and (2) an associative effect: facilitation in learning degraded response-shock contingencies. These are the opposite of helplessness effects, operationally and descriptively, and may be opposite in process as well.