Johnson, M. W., & Bickel, W. K. (2002).
Within-subject comparison of real and hypothetical money rewards in delay discounting.
Journal of the Experimental Analysis of Behavior,
77, 129-146.
A within-subject design, using human participants, compared delay
discounting functions for real and hypothetical money rewards.
Both real and hypothetical rewards were studied across a range
that included $10 to $250. For 5 of the 6 participants, no
systematic difference in discount rate was observed in response
to real and hypothetical choices, suggesting that hypothetical
rewards may often serve as a valid proxy for real rewards in
delay discounting research. By measuring discounting at an
unprecedented range of real rewards, this study has also
systematically replicated the robust finding in human delay
discounting research that discount rates decrease with increasing
magnitude of reward. A hyperbolic decay model described the data
better than an exponential model.
Key words: delay discounting, real rewards, hypothetical rewards,
magnitude, hyperbolic, choice, humans