Relative persistence of behavior: a fundamental measure of relative reinforcing effects.

Relative persistence of behavior is measured in terms of rates of behavior at a higher schedule value divided by rates of behavior at a lower schedule value and then multiplied by 100 to express the result as a percentage. Relative persistence of behavior is a direct function of reinforcer size over a broad range of values. In 1 study, food was the reinforcer; however, in most studies of persistence, drug reinforcers were used, and the drugs were taken orally or intravenously. A variety of reinforcing drugs were studied: barbiturates, opioids, psychomotor stimulants, a dissociative anesthetic, and alcohol. Both ratio and interval schedules were used to study relative persistence of behavior in human participants, male and female rhesus monkeys (Macaca mulatta), and rats. Thus, studies of persistence are based on results of an extensive set of conditions. The results support the proposition that relative persistence of behavior is a fundamental measure of relative reinforcing effects.