Title

Discounting of Delayed Rewards in Opioid-Dependent Outpatients: Exponential or Hyperbolic Discounting Functions?

Document Type

Article

Journal/Book Title/Conference

Experimental and Clinical Psychopharmacology

Volume

7

Issue

3

Publisher

American Psychological Association

Publication Date

1999

First Page

284

Last Page

293

DOI

10.1037/1064-1297.7.3.284

Abstract

Recent theories of substance abuse have used value discounting of delayed rewards to partly explain the decision to take drugs. Normative-economic theory holds that an exponential function describes the effects of delay on discounting, whereas the matching law posits a hyperbolic discounting function. The ability of these functions to describe 18 human heroin-dependent individuals' monetary- and heroin-reward delay-discounting functions was assessed. In the 1st condition, participants chose between immediate and delayed hypothetical monetary rewards. Delayed rewards were $1,000, and the immediate reward amount was adjusted until choices reflected indifference. In the 2nd condition, participants chose between immediate and delayed heroin (the delayed amount was that which each participant reported he or she could purchase with $1,000). The hyperbolic function produced significantly higher R² values and significantly lower sums of squared error values. Consistent with previous findings, delayed heroin rewards were discounted at a significantly higher rate than were delayed monetary rewards.

Comments

Originally published by the American Psychological Association.

This article may not exactly replicate the final version published in the APA journal. It is not the copy of record.

Publisher's PDF available for purchase through remote link.

Note: Greg Madden was affiliated with the University of Vermont at time of publication.

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