Rodriguez Christian A, Turner Brandon M, McClure Samuel M
Department of Psychology, Stanford University, Stanford, California, United States of America.
PLoS One. 2014 Feb 28;9(2):e90138. doi: 10.1371/journal.pone.0090138. eCollection 2014.
Two separate cognitive processes are involved in choosing between rewards available at different points in time. The first is temporal discounting, which consists of combining information about the size and delay of prospective rewards to represent subjective values. The second involves a comparison of available rewards to enable an eventual choice on the basis of these subjective values. While several mathematical models of temporal discounting have been developed, the reward selection process has been largely unexplored. To address this limitation, we evaluated the applicability of the Linear Ballistic Accumulator (LBA) model as a theory of the selection process in intertemporal choice. The LBA model formalizes the selection process as a sequential sampling algorithm in which information about different choice options is integrated until a decision criterion is reached. We compared several versions of the LBA model to demonstrate that choice outcomes and response times in intertemporal choice are well captured by the LBA process. The relationship between choice outcomes and response times that derives from the LBA model cannot be explained by temporal discounting alone. Moreover, the drift rates that drive evidence accumulation in the best-fitting LBA model are related to independently estimated subjective values derived from various temporal discounting models. These findings provide a quantitative framework for predicting dynamics of choice-related activity during the reward selection process in intertemporal choice and link intertemporal choice to other classes of decisions in which the LBA model has been applied.
在不同时间点可得的奖励之间进行选择涉及两个独立的认知过程。第一个是时间折扣，它包括结合有关预期奖励大小和延迟的信息来表示主观价值。第二个过程涉及对可得奖励进行比较，以便最终根据这些主观价值做出选择。虽然已经开发了几种时间折扣的数学模型，但奖励选择过程在很大程度上尚未得到探索。为了解决这一局限性，我们评估了线性弹道积累器（LBA）模型作为跨期选择中选择过程理论的适用性。LBA模型将选择过程形式化为一种顺序采样算法，其中关于不同选择选项的信息被整合，直到达到决策标准。我们比较了LBA模型的几个版本，以证明LBA过程能够很好地捕捉跨期选择中的选择结果和反应时间。仅靠时间折扣无法解释LBA模型得出的选择结果与反应时间之间的关系。此外，在拟合效果最佳的LBA模型中驱动证据积累的漂移率与从各种时间折扣模型独立估计的主观价值相关。这些发现为预测跨期选择中奖励选择过程中与选择相关活动的动态提供了一个定量框架，并将跨期选择与已应用LBA模型的其他决策类别联系起来。
