Empirical estimation of consistency parameter in intertemporal choice based on Tsallis’ statistics

Taiki Takahashi, Hidemi Oono and Mark H.B. Radford

Physica A: Statistical Mechanics and its Applications, 2007, vol. 381, issue C, 338-342

Abstract: Impulsivity and inconsistency in intertemporal choice have been attracting attention in econophysics and neuroeconomics. Although loss of self-control by substance abusers is strongly related to their inconsistency in intertemporal choice, researchers in neuroeconomics and psychopharmacology have usually studied impulsivity in intertemporal choice using a discount rate (e.g. hyperbolic k), with little effort being expended on parameterizing subject's inconsistency in intertemporal choice. Recent studies using Tsallis’ statistics-based econophysics have found a discount function (i.e. q-exponential discount function), which may continuously parameterize a subject's consistency in intertemporal choice. In order to examine the usefulness of the consistency parameter (0⩽q⩽1) in the q-exponential discounting function in behavioral studies, we experimentally estimated the consistency parameter q in Tsallis’ statistics-based discounting function by assessing the points of subjective equality (indifference points) at seven delays (1 week–25 years) in humans (N=24). We observed that most (N=19) subjects’ intertemporal choice was completely inconsistent (q=0, i.e. hyperbolic discounting), the mean consistency (0⩽q⩽1) was smaller than 0.5, and only one subject had a completely consistent intertemporal choice (q=1, i.e. exponential discounting). There was no significant correlation between impulsivity and inconsistency parameters. Our results indicate that individual differences in consistency in intertemporal choice can be parameterized by introducing a q-exponential discount function and most people discount delayed rewards hyperbolically, rather than exponentially (i.e. mean q is smaller than 0.5). Further, impulsivity and inconsistency in intertemporal choice can be considered as separate behavioral tendencies. The usefulness of the consistency parameter q in psychopharmacological studies of addictive behavior was demonstrated in the present study.

Keywords: Discounting; Neuroeconomics; Impulsivity; Econophysics (search for similar items in EconPapers)
Date: 2007
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Citations: View citations in EconPapers (18)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:phsmap:v:381:y:2007:i:c:p:338-342

DOI: 10.1016/j.physa.2007.03.038

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Physica A: Statistical Mechanics and its Applications is currently edited by K. A. Dawson, J. O. Indekeu, H.E. Stanley and C. Tsallis

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