Stud γ objective : " Timepreference " and " temporal discounting " refer ・ to a decrease inthe subjective value of a reward as the delay to its receipt increases . Economics and psychology have attempted to explain this phe − nomenon from different viewpoints and with different methods . In economics , early researchers on time pref − erence proposed exponentia1 functions to show rationa1 allocations of consumption between the present and the future . However , recent research on time

more »

... has Feported anomalies that cannot be described by exponential functions , and so new discounting mQdelshave been proposed thatcan describe these anoma 【 ies . In psychology , animal and human temporal discounting are considered to be described better by hyperbolic functions than by exponential ones . Economic variables correlating to the discounting rate have been reported . Economic researchers have to measure discounting rate in real − choice situations . It is expected that , in both economics and psychology , temporal discounting research will be integrated into an interdisciplinary re − search area that brings further understanding ofthis phenomenon ,