Madden, G. J., Bickel, W. K., & Jacobs, E. A. (2000).
Three predictions of the economic concept of unit price in a choice context.
Journal of the Experimental Analysis of Behavior,
73, 45-64.
Economic theory makes three predictions about consumption and
response output in a choice situation: (a) When plotted on
logarithmic coordinates, total consumption (i.e., summed across
concurrent sources of reinforcement) should be a positively
decelerating function, and total response output should be a
bitonic function of unit price increases; (b) total consumption
and response output should be determined by the value of the unit
price ratio, independent of its cost and benefit components; and
(c) when a reinforcer is available at the same unit price across
all sources of reinforcement, consumption should be equal between
these sources. These predictions were assessed in human cigarette
smokers who earned cigarette puffs in a two-choice situation at a
range of unit prices. In some sessions, smokers chose between
different amounts of puffs, both available at identical unit
prices. Individual subjects’ data supported the first two
predictions but failed to support the third. Instead, at low unit
prices, the relatively larger reinforcer (and larger response
requirement) was preferred, whereas at high unit prices, the
smaller reinforcer (and smaller response requirement) was
preferred. An expansion of unit price is proposed in which
handling costs and the discounted value of reinforcers available
according to ratio schedules are incorporated.
Key words: behavioral economics, unit price, drug
self-administration, delay discounting, matching law, plunger
pull, humans