Effects of coping behavior in different warning signal conditions on stress pathology in rats.

Rats received electric shock that was preceded by either a warning signal, a series of signals forming an "external clock," or no signal at all. In all conditions, subjects which could avoid and/or escape shock developed less ulceration than, did yoked "helpless" animals which received exactly the same shock (through fixed electrodes wired in series) but had no control over shock. Presence or absence of a warning signal did, however, have an effect: A discrete warning signal reduced the ulceration both of subjects having control over shock and of yoked helpless subjects. A theory is proposed to explain how psychological factors determine the development of gastric ulceration in stress situations, and the present results are examined in relation to it.