Predictable vs. unpredictable shock: Preference behavior and stomach ulceration

Abstract Rats given a choice for predictable or unpredictable shock chose predictable shock and developed fewer stomach ulcers than rats who could not make this choice, and received only unpredictable shock. A yoked control procedure was utilized in a tilt shuttlecage apparatus with two levels of shock intensity and four treatments of predictability. Predictable shock was preferred by both low and high intensity shock groups, but was slower to develop at the high intensity shock level. Unpredictable shock resulted in a high frequency of animals with stomach ulcers at both shock intensities, whereas significantly fewer animals developed ulcers who received predictable shock at the low intensity shock level. Results were discussed with respect to the safety signal hypothesis and Weiss' Relevant Feedback hypothesis on stomach ulceration in rats.