Discounting or Priority: Which Rule Dominates the Intertemporal Choice Process?
LIU Hong-Zhi1,2; JIANG Cheng-Ming3; RAO Li-Lin1; LI Shu1
(1 Key Laboratory of Behavioral Science, Institute of Psychology, Chinese Academy of Sciences, Beijing 100101, China) (2 University of Chinese Academy of Sciences, Beijing 100101, China) (3 Center for Brain and Management Science, College of Economics and Management, Zhejiang University of Technology, Hangzhou 310023, China)
Intertemporal choice refers to decisions that involve tradeoffs among outcomes at different points of time (Frederick, Loewenstein, & O'Donoghue, 2002; Prelec & Loewenstein, 1991). It is not only a unique characteristic of human behavior, but is also a relevant matter to policymaking and national welfare. Two families of models on intertemporal choice exist. One is the family of discounting models, such as discounted utility model or hyperbolic discounting model. These models assume that people discount future outcomes by their immediacy and subsequently compare the discounted values. The other is the family of priority models, such as tradeoff model or equate-to-differentiate model. These models assume that people compare the differences between dimensions and make decisions along a single dimension. Considerable debate has occurred regarding the strategy that people adopt when making intertemporal choices. The extant evidence based on outcome tests has been inconclusive. To address this debate, we used a process-test paradigm called process dissociation procedure (PDP) to explore whether the strategy that underlies intertemporal choice is a discounting strategy or a priority strategy. Based on dual-system theory, discounting strategy is presumably driven by an analytic system, whereas priority strategy is presumably driven by a heuristic system. Following the logic of PDP, we proposed the following hypothesis: if decisions are based on discounting (priority) strategy, manipulating the factors that affect this strategy results in the transformation of the contribution of the analytic (heuristic) system, whereas the contribution of the heuristic (analytic) remains unchanged. A total of 423 college students participated in the experiments. Specifically, 154 college students participated in Experiment 1, 102 in Experiment 2, and 167 in Experiment 3. In Experiment 1, to ensure that only the analytic system is affected, we manipulated the decision goal by instructing participants to make decisions in a rational manner. In Experiment 2, we examined the effect of cognitive load on the heuristic system by instructing participants to remember several numbers. In Experiment 3, we manipulated strategy priming to simultaneously affect the analytic and heuristic systems by asking participants to answer priming questions before the experiment. The results of Experiment 1 indicated that the decision goal, which was supposed to affect the analytic system, failed to modify the contribution of the analytic system. The results of Experiment 2 showed that cognitive load, which was supposed to affect the heuristic system, modified the contribution of the heuristic system. The results of Experiment 3 suggested that strategy priming, which was supposed to affect both systems, modified the contribution of the heuristic system but did not affect the analytic system. Overall, the results of the three experiments consistently showed that people may adopt a priority strategy, rather than a discounting strategy, when making intertemporal choices. Our findings provide further evidence for the proposition that the priority strategy of heuristic systems dominates the intertemporal choice-making process. This research deepens our understanding of the mechanisms that underlie intertemporal choice and provides a theoretical foundation for establishing and stipulating intertemporal policies, laws, and regulations.