Delay Discounting and Alcohol Abusers: More Impatient Even When Not Impulsive?

Abstract

Many studies have found: (i) substance abusers discount delayed rewards more than non-abusers do, which is widely interpreted as implying that substance abusers are more impulsive than non-abusers; and (ii) discounting increases most sharply with time when delays are brief, and then increases more slowly as delays grow longer, in a pattern called “hyperbolic” that is at odds with exponential discounting. In a sample of 157 college students we implement a new delay discounting task introduced by Andreoni and Sprenger (2012a,b) that faces participants with rather complex choices about sooner and later rewards. We also follow Andreoni and Sprenger in giving participants explicit assurances that chosen future rewards will, in fact, be delivered, which past studies have not. Echoing Andreoni and Sprenger, but contrary to (ii), we find that most participants’ discounting is exponential in this new task. We nonetheless confirm (i). We discuss several possible explanations for our participants discounting exponentially. That both participants with problems and those without tend to discount exponentially in our task indicates neither group is behaving impulsively in our experimental setting. Finding, as we do, marked differences in exponential discounting between those with alcohol problems and those without suggests that better understanding the psychological roots and malleability of exponential discounting (that is, of impatience in the absence of impulsivity) might lead to new therapies for reducing substance abuse.

Keywords: addiction, present bias, substance abuse, discounting

JEL Classification: C91, D12, D81