Delay discounting of saccharin in rhesus monkeys.
The value of a reinforcer decreases as the time until its receipt increases, a phenomenon referred to as delay discounting. Although delay discounting of non-drug reinforcers has been studied extensively in a number of species, our knowledge of discounting in non-human primates is limited. In the present study, rhesus monkeys were allowed to choose in discrete trials between 0.05% saccharin delivered in different amounts and with different delays. Indifference points were calculated and discounting functions were established. Discounting functions for saccharin were well described by a hyperbolic function. Moreover, the discounting rates for saccharin in all six monkeys were comparable to those of other non-human animals responding for non-drug reinforcers. Also consistent with other studies of non-human animals, changing the amount of a saccharin reinforcer available after a 10-s delay did not affect its relative subjective value. Discounting functions for saccharin were steeper than we found in a previous study with cocaine, raising the possibility that drugs such as cocaine may be discounted less steeply than non-drug reinforcers.
Freeman
Kevin B
KB
Division of Neurobiology and Behavior Research, Department of Psychiatry and Human Behavior, The University of Mississippi Medical Center, Jackson, MS 39216, United States. kfreeman@psychiatry.umsmed.edu
Green
Leonard
L
Myerson
Joel
J
Woolverton
William L
WL
D000818:Animals; D002755:Choice Behavior; D008253:Macaca mulatta / Q000523:psychology*; D008297:Male; D012055:Reinforcement Schedule; D012054:Reinforcement, Psychology; D012439:Saccharin / Q000008:administration & dosage*; D013549:Sweetening Agents / Q000008:administration & dosage*; D013998:Time Perception
D013549:Sweetening Agents; D012439:Saccharin