Blackburn Marianna, El-Deredy Wael
School of Psychological Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
Behav Processes. 2013 Mar;94:9-18. doi: 10.1016/j.beproc.2012.11.005. Epub 2012 Nov 29.
The world is full of choices where outcomes are both delayed and probabilistic. Whilst the delay discounting framework provides a platform for examining the relationship between dimensions of time and probability, the majority of research has considered these factors in isolation, or made assumptions about their equivalence. In order to address these issues, we present a novel measurement approach for assessing the discounting of delayed and uncertain outcomes. We conducted two experiments which compared discounting on three types of delay discounting task (standard, uncertain outcome, and uncertain amount) and examined the robustness of using a delayed and uncertain outcome's certainty equivalent relative to its expected value as a method for measuring discount rates. Both experiments demonstrated that discounting is best modelled by a hyperbolic function that describes subjective values relative to their certain equivalents. Moreover, when modelled this way, clear differences emerged between the different aspects of uncertainty (outcome vs. amount) dependent on whether outcomes were delayed gains or losses. This was true for both group and individual delay discounting data, as well as for both outcomes that were uncertain with respect to whether they would occur or not and outcomes that were uncertain with respect to what their magnitude would be when they occurred.
世界充满了结果既延迟又具有概率性的选择。虽然延迟折扣框架为研究时间维度与概率之间的关系提供了一个平台，但大多数研究都是孤立地考虑这些因素，或者对它们的等效性做出假设。为了解决这些问题，我们提出了一种新颖的测量方法，用于评估延迟和不确定结果的折扣。我们进行了两项实验，比较了三种类型的延迟折扣任务（标准、不确定结果和不确定金额）的折扣情况，并检验了使用延迟和不确定结果的确定性等价物相对于其预期值作为测量折扣率方法的稳健性。两项实验均表明，折扣最好用双曲线函数来建模，该函数描述相对于其确定性等价物的主观价值。此外，当以这种方式建模时，根据结果是延迟收益还是损失，不确定性的不同方面（结果与金额）之间出现了明显差异。这对于群体和个体延迟折扣数据都是如此，对于结果是否会发生不确定的情况以及结果发生时其大小不确定的情况也是如此。
