Cheng Jiuqing, González-Vallejo Claudia
Department of Psychology, Ohio University, Athens, Ohio, United States of America.
PLoS One. 2014 Nov 12;9(11):e111378. doi: 10.1371/journal.pone.0111378. eCollection 2014.
The single parameter hyperbolic model has been frequently used to describe value discounting as a function of time and to differentiate substance abusers and non-clinical participants with the model's parameter k. However, k says little about the mechanisms underlying the observed differences. The present study evaluates several alternative models with the purpose of identifying whether group differences stem from differences in subjective valuation, and/or time perceptions. Using three two-parameter models, plus secondary data analyses of 14 studies with 471 indifference point curves, results demonstrated that adding a valuation, or a time perception function led to better model fits. However, the gain in fit due to the flexibility granted by a second parameter did not always lead to a better understanding of the data patterns and corresponding psychological processes. The k parameter consistently indexed group and context (magnitude) differences; it is thus a mixed measure of person and task level effects. This was similar for a parameter meant to index payoff devaluation. A time perception parameter, on the other hand, fluctuated with contexts in a non-predicted fashion and the interpretation of its values was inconsistent with prior findings that supported enlarged perceived delays for substance abusers compared to controls. Overall, the results provide mixed support for hyperbolic models of intertemporal choice in terms of the psychological meaning afforded by their parameters.
单参数双曲线模型经常被用于描述价值折扣作为时间的函数，并通过该模型的参数k来区分药物滥用者和非临床参与者。然而，k对于观察到的差异背后的机制说明甚少。本研究评估了几种替代模型，目的是确定组间差异是否源于主观估值和/或时间感知的差异。使用三个双参数模型，加上对14项研究中471条无差异点曲线的二次数据分析，结果表明添加一个估值或一个时间感知函数会导致更好的模型拟合。然而，由于第二个参数所赋予的灵活性而带来的拟合度提高并不总是能更好地理解数据模式和相应的心理过程。k参数始终能反映组间和情境（量级）差异；因此它是个体和任务水平效应的混合度量。对于一个旨在反映收益贬值的参数来说也是如此。另一方面，一个时间感知参数以一种不可预测的方式随情境波动，其值的解释与先前的研究结果不一致，先前的研究结果支持与对照组相比，药物滥用者感知到的延迟会延长。总体而言，就其参数所赋予的心理意义而言，这些结果为跨期选择的双曲线模型提供了好坏参半的支持。
