Deconstructing relative reinforcing efficacy and situating the measures of pharmacological reinforcement with behavioral economics: a theoretical proposal
In this experiment, we compared behavioral economic measures and measures of the relative reinforcing efficacy of cigarettes and money between-participants. The experiment proceeded in two phases. In the first phase, money and cigarettes were available on separate progressive ratio (PR) schedules when they were solely available. The response requirement for the PR schedule increased across sessions, rather than within a session. In the second phase, money and cigarettes were made concurrently available at some of the response requirements employed during the PR schedule. Measures of (1) PR breakpoint, (2) peak response rate, (3) preference, (4) elasticity and (5) Pmax (the price at which the greatest amount of responding occurs) were compared within participant. Across the PR- and concurrent-schedule conditions, the three measures of reinforcing efficacy (breakpoint, response rate and preference) yielded an inconsistent assessment of the relative reinforcing efficacy of money and cigarettes. The reinforcer that resulted in greater peak response rates varied across subjects, while PR breakpoint was higher for cigarettes in all participants. Further, in concurrent schedules, preferences for cigarettes or money reversed across the response requirements. Behavioral economic analyses suggest that Pmax and elasticity are related to PR breakpoint, and that preference can be predicted from a comparison of the demand curves under single-schedule conditions. Implications for the concept of reinforcing efficacy are discussed.