PITUITARY-ADRENAL ACTIVITY UNDER DIFFERENT APPETITIVE EXTINCTION PROCEDURES

Rats were exposed to 1 of 4 treatment related to the extinction of appetitive operant behavior. As previously demonstrated, extinction by the traditional method of food withdrawal resulted in elevated levels of plasma corticosterone. When extinction consisted of breaking the contingency between responding and food delivery, steroid levels were initially unchanged from pre-extinction values, but declined as the rate of responding was reduced. The elimination of responding by lever removal yielded unchanged steroid levels in the absence of food, but significantly suppressed plasma corticosterone when food continued to be delivered. The data are discussed in support of Weiss'' theory of coping which stresses the number of responses made by the organism and the amount of stimulus feedback.