Abstract
Pain, as a private experience, cannot be measured directly; it can only be inferred from pain-associated behaviors. An objective measure of such behavior is the observable impairment of functioning, e.g., a reduction in performance. It has been suggested that pain behaviors can eventually cease to be a function of neural activity and come under the control of external environmental contingencies. In an initial attempt to test this suggestion, pairs of rats were housed separately in chambers for the duration of the experiment. Their normal activity in this condition included lever-pressing for food on a cooperative schedule of reinforcement. The ratio of responses showed the division of labor. The grid floor of one chamber was then electrified at low amperage, reducing the proportion of responses made by that subject. This reduction was complemented by an increase in the amount of responding by the partner. Following termination of shock, baseline ratios were slow to recover, demonstrating chronically impaired functioning. These results support Fordyce's suggested etiology of chronic pain behaviors in humans.
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