  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 independent of discounting
rate and non-linearity 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). 63% of the participants had intertemporal choice patterns
corresponding best to hyperbolic functions. Even when the perceptual bias in
the temporal magnitude estimations was compensated in the discounting rate
computation, the data of 8 out of 14 participants continued exhibiting temporal
inconsistency. The results suggest that temporal inconsistency in discounting
rate can be explained to different degrees by the bias in temporal
representations. Non-linearity in temporal representation and discounting rate
should be evaluated on an individual basis. Keywords: Intertemporal choice,
temporal magnitude, model comparison, impatience, time inconsistency
