Madden, G.J., Smethells, J.R., Ewan, E.E. & Hursh, S.R. (2007).
Tests of behavioral-economic assessments of relative reinforcer efficacy: economic substitutes.
Journal of the Experimental Analysis of Behavior, 87, 219-240.
This experiment was conducted to test predictions of two behavioral-economic approaches to quantifying relative
reinforcer efficacy. According to the first of these approaches, characteristics of averaged normalized demand
curves may be used to predict progressive-ratio breakpoints and peak responding. The second approach, the demand
analysis, rejects the concept of reinforcer efficacy, arguing instead that traditional measures of relative
reinforcer efficacy (breakpoint, peak response rate, and choice) correspond to specific characteristics of
non-normalized demand curves. The accuracy of these predictions was evaluated in rats’ responding for food or
fat: two reinforcers known to function as partial substitutes. Consistent with the first approach, predicted
peak normalized response output values (Omax) obtained under single-schedule conditions ordinally predicted
progressive-ratio breakpoints and peak responding. Predictions of the demand analysis had mixed success. Pmax
and Omax were significantly correlated with PR breakpoints and peak responding (respectively) when fat, but not
when food, was the reinforcer. Relative consumption of food and fat under single schedules of reinforcement did
not predict preference better than chance. The normalized demand analysis is supplemented with the economic
concept of diminishing marginal utility, to predict preference shifts across the range of food and fat prices
examined.
Key words: behavioral economics, relative reinforcer efficacy, substitute, minimum-needs, rat, lever press