The Role of Time Estimation in Decreased Impatience in Intertemporal Choice

The role of specific cognitive processes in deviations from constant discounting in intertemporal choice is not well understood. We evaluated decreased impatience in intertemporal choice tasks in a fashion that isolates discounting rate and nonlinearity in long scale time representation; nonlinear time representation was expected to explain inconsistencies in discounting rate. Participants performed temporal magnitude estimation and intertemporal choice tasks. Psychophysical functions for time intervals were estimated by fitting linear and power functions, while discounting functions were estimated by fitting exponential and hyperbolic functions. The temporal magnitude estimates of 65% of the participants were better fit with power functions (mostly compression) and 63% of the participants had intertemporal choice patterns corresponding best to hyperbolic functions. When the perceptual bias of the participants that exhibited hyperbolic functions was compensated in the discounting rate computation, over half of them continued exhibiting temporal inconsistency. Therefore, the results suggest that temporal inconsistency in discounting rate cannot be fully explained by the bias in temporal representations. Nonlinearity in temporal representation and discounting rate should be evaluated on an individual basis.