Discounting of Reward Sequences: a Test of Competing Formal Models of Hyperbolic Discounting

Humans are known to discount future rewards hyperbolically in time. Nevertheless, a formal recursive model of hyperbolic discounting has been elusive until recently, with the introduction of the hyperbolically discounted temporal difference (HDTD) model. Prior to that, models of learning (especial...

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Main Authors: Noah eZarr, Joshua W. Brown, William eAlexander
Format: Article
Language:English
Published: Frontiers Media S.A. 2014-03-01
Series:Frontiers in Psychology
Subjects:
Online Access:http://journal.frontiersin.org/Journal/10.3389/fpsyg.2014.00178/full
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author Noah eZarr
Joshua W. Brown
William eAlexander
author_facet Noah eZarr
Joshua W. Brown
William eAlexander
author_sort Noah eZarr
collection DOAJ
description Humans are known to discount future rewards hyperbolically in time. Nevertheless, a formal recursive model of hyperbolic discounting has been elusive until recently, with the introduction of the hyperbolically discounted temporal difference (HDTD) model. Prior to that, models of learning (especially reinforcement learning) have relied on exponential discounting, which generally provides poorer fits to behavioral data. Recently, it has been shown that hyperbolic discounting can also be approximated by a summed distribution of exponentially discounted values, instantiated in the µAgents model. The HDTD model and the µAgents model differ in one key respect, namely how they treat sequences of rewards. The µAgents model is a particular implementation of a parallel discounting model, which values sequences based on the summed value of the individual rewards whereas the HDTD model contains a nonlinear interaction. To discriminate among these models, we ascertained how subjects discounted a sequence of three rewards, and then we tested how well each candidate model fit the subject data. The results show that the parallel model generally provides a better fit to the human data.
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spelling doaj.art-6907623bdcb74b81bde77c94b0caafaf2022-12-22T01:24:03ZengFrontiers Media S.A.Frontiers in Psychology1664-10782014-03-01510.3389/fpsyg.2014.0017871173Discounting of Reward Sequences: a Test of Competing Formal Models of Hyperbolic DiscountingNoah eZarr0Joshua W. Brown1William eAlexander2Indiana UniversityIndiana UniversityGhent UniversityHumans are known to discount future rewards hyperbolically in time. Nevertheless, a formal recursive model of hyperbolic discounting has been elusive until recently, with the introduction of the hyperbolically discounted temporal difference (HDTD) model. Prior to that, models of learning (especially reinforcement learning) have relied on exponential discounting, which generally provides poorer fits to behavioral data. Recently, it has been shown that hyperbolic discounting can also be approximated by a summed distribution of exponentially discounted values, instantiated in the µAgents model. The HDTD model and the µAgents model differ in one key respect, namely how they treat sequences of rewards. The µAgents model is a particular implementation of a parallel discounting model, which values sequences based on the summed value of the individual rewards whereas the HDTD model contains a nonlinear interaction. To discriminate among these models, we ascertained how subjects discounted a sequence of three rewards, and then we tested how well each candidate model fit the subject data. The results show that the parallel model generally provides a better fit to the human data.http://journal.frontiersin.org/Journal/10.3389/fpsyg.2014.00178/fullBehavioral Researchdiscountingmodel fittingExponential discountinghyperbolic discountingtemporal difference learning
spellingShingle Noah eZarr
Joshua W. Brown
William eAlexander
Discounting of Reward Sequences: a Test of Competing Formal Models of Hyperbolic Discounting
Frontiers in Psychology
Behavioral Research
discounting
model fitting
Exponential discounting
hyperbolic discounting
temporal difference learning
title Discounting of Reward Sequences: a Test of Competing Formal Models of Hyperbolic Discounting
title_full Discounting of Reward Sequences: a Test of Competing Formal Models of Hyperbolic Discounting
title_fullStr Discounting of Reward Sequences: a Test of Competing Formal Models of Hyperbolic Discounting
title_full_unstemmed Discounting of Reward Sequences: a Test of Competing Formal Models of Hyperbolic Discounting
title_short Discounting of Reward Sequences: a Test of Competing Formal Models of Hyperbolic Discounting
title_sort discounting of reward sequences a test of competing formal models of hyperbolic discounting
topic Behavioral Research
discounting
model fitting
Exponential discounting
hyperbolic discounting
temporal difference learning
url http://journal.frontiersin.org/Journal/10.3389/fpsyg.2014.00178/full
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