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Original Research ARTICLE

This article is part of a Research Topic

Temporal discounting and inter-temporal choice in rhesus monkeys

Jaewon Hwang¹, Soyoun Kim² and Daeyeol Lee^2*

Department of Brain and Cognitive Sciences, University of Rochester, Rochester, NY, USA

Department of Neurobiology, Yale University School of Medicine, New Haven, CT, USA

Humans and animals are more likely to take an action leading to an immediate reward than actions with delayed rewards of similar magnitudes. Although such devaluation of delayed rewards has been almost universally described by hyperbolic discount functions, the rate of this temporal discounting varies substantially among different animal species. This might be in part due to the differences in how the information about reward is presented to decision makers. In previous animal studies, reward delays or magnitudes were gradually adjusted across trials, so the animals learned the properties of future rewards from the rewards they waited for and consumed previously. In contrast, verbal cues have been used commonly in human studies. In the present study, rhesus monkeys were trained in a novel inter-temporal choice task in which the magnitude and delay of reward were indicated symbolically using visual cues and varied randomly across trials. We found that monkeys could extract the information about reward delays from visual symbols regardless of the number of symbols used to indicate the delay. The rate of temporal discounting observed in the present study was comparable to the previous estimates in other mammals, and the animalÃƒÂ¯Ã‚Â¿Ã‚Â½s choice behavior was largely consistent with hyperbolic discounting. Our results also suggest that the rate of temporal discounting might be infl uenced by contextual factors, such as the novelty of the task. The fl exibility furnished by this new inter-temporal choice task might be useful for future neurobiological investigations on inter-temporal choice in non-human primates.

Keywords:

reward, neuroeconomics, decision making, prefrontal cortex

Citation:

Hwang J, Kim S and Lee D (2009). Temporal discounting and inter-temporal choice in rhesus monkeys. Front. Behav. Neurosci. 3:9. doi:10.3389/neuro.08.009.2009

Received:

10 April 2009;

Paper pending published:

17 May 2009;

Accepted:

01 June 2009;

Published online:

11 June 2009.

Edited by:

Jeansok J. Kim, University of Washington, USA

Reviewed by:

Ben Seymour, Wellcome Trust Centre for Neuroimaging, UK
Veit Stuphorn, Johns Hopkins University, USA

© 2009 Hwang, Kim and Lee. This is an open-access article subject to an exclusive license agreement between the authors and the Frontiers Research Foundation, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are credited.

*Correspondence:

Daeyeol Lee, Department of Neurobiology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06510, USA. e-mail: daeyeol.lee@yale.edu