Unpredictable and Uncontrollable Aversive Events

Publisher Summary Aversive events occur frequently in the life histories of all organisms. Long-lasting behavior pecularities, emotional illnesses, and anomalies of perception and thinking are attributed to such events. Apart from genetic or constitutional variables that might lead to individual differences in reactivity to aversive stimuli, there are a host of environmental variables that help to understand such individual differences. Two such environmental variables are the predictability and controllability of aversive events. This chapter reviews some of the behavioral and physiological consequences of aversive events that are either unpredictable, uncontrollable by a subject, or both. Unpredictable painful events turn out to be more distressing than are predictable ones. They generate more ulcers and intensify subjective reports of painfulness and anxiety. Both people and animals choose, if given the choice, predictable painful events over unpredictable ones. Uncontrollable painful events can interfere with an organism's ability later to solve problems to escape or avoid these events. They can lead to a phenomenon labeled “helplessness.” The chapter discusses the current status of research and theory concerning these phenomena. It describes a two-dimensional representation of the operations involved in instrumental training and Pavlovian conditioning. The chapter further reviews a number of theoretical interpretations of the effects of uncontrollable shocks on subsequent escape/avoidance learning and discusses the theoretical interpretations of the effects of unpredictable shocks on behavioral and physiological responses: the preparatory response hypothesis and the safety signal hypotheses.