Delayed reward and cost discounting

Participants (N = 28) chose between smaller, immediate and larger, delayed hypothetical monetary amounts in a cost and a reward condition. For both co nditions, the choice procedure yielded equivalence points that measure the immediate amount reward or cost that is subjectively equivalent to the larg er delayed reward or cost. Equivalence points from each of eight delays wer e used to estimate a discounting parameter for both hyperbolic and exponent ial discount functions. Hyperbolic functions accounted for more of the vari ance in both the reward and the cost condition, and delayed reward and cost discounting was significantly correlated. Participants discounted the valu e of delayed rewards to a greater degree than delayed costs. Previous resea rch has found that substance abusers discount delayed rewards more than con trols. Implications of the present findings for substance abuse and other h ealth behaviors are discussed.