ISSN 0439-755X
CN 11-1911/B

Acta Psychologica Sinica ›› 2016, Vol. 48 ›› Issue (1): 59-72.doi: 10.3724/SP.J.1041.2016.00059

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A process test of priority models of intertemporal choice

JIANG Cheng-Ming1,2; LIU Hong-Zhi2,3; CAI Xiao-Hong2,3; LI Shu2   

  1. (1 College of Economics and Management, Zhejiang University of Technology, Hangzhou 310023, China)
    (2 Key Laboratory of Behavioral Science, Institute of Psychology, Chinese Academy of Sciences, Beijing 100101, China)
    (3 University of Chinese Academy of Sciences, Beijing 100101, China)
  • Received:2014-06-28 Published:2016-01-25 Online:2016-01-25
  • Contact: LI Shu, Email: lishu@psych.ac.cn; s.li@UNSWalumni.com

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Abstract:

 Intertemporal choice is vital to human survival and development, hence the interest of scientists today in analyzing how it is made. Mainstream theories hold that a discounting process serves as basis for making choices, but other theories forego this process. For example, priority models, such as the tradeoff model and equate-to-differentiate theory, show that individuals tend to compare the difference between dimensions of delay and outcome before deciding in a single dimension when selecting between a smaller, sooner outcome (SS) and a larger, later outcome (LL). To tackle this question and improve our knowledge of the mechanisms underlying human decision making, concrete evidence based on psychological process is required. In the current study, we tested priority models by using a process-oriented method.

A total of 822 college students participated in the study; 238 participated in Experiment 1A, 194 in Experiment 1B, 97 in Experiment 1C, and 293 in Experiment 2. In Experiment 1A, we manipulated the differences of two alternatives (i.e., SS and LL) in terms of monetary outcome (in Problem 1) and delay (in Problem 2). We then asked participants to indicate their preference between SS and LL and to compare the difference on the delay dimension with that on the outcome dimension (we called this process “difference- comparing process”). The aim of Experiment 1A was to examine whether one’s preference was mediated by the difference-comparing process. For Experiment 1B, we altered the procedure used in Experiment 1A (i.e., participants were first asked to conduct the difference-comparing process then indicate their preference) because we wanted to ensure that the difference-comparing process is the online process of selecting rather than the artifact of the experimental procedure. In Experiment 1C, we asked participants to indicate their preference and conduct the difference-comparing process at separate occasions. The aim of Experiment 1C was to address the problem of common-method bias. In Experiment 2, we examined whether the difference-comparing process can explain anomalies cited in previous studies on intertemporal choice.
The results of Experiment 1 showed that the difference-comparing process mediated the preferences of the participants. This finding implied that the participants will more likely select LL when the perceived difference on the outcome dimension is larger than that on the delay dimension, whereas they are likely to select SS when the perceived difference on the delay dimension is bigger than that on the outcome dimension. In addition, we inferred that increasing the magnitude of both outcomes by the same multiplicative constant increases the perceived difference on the outcome dimension, hence the magnitude effect. Adding a constant to both delays decreases the perceived difference on the outcome dimension, hence the common difference effect. Replicating the results of Experiment 1A, Experiment 1B also demonstrated that the difference-comparing process is an online selection process, and Experiment 1C mitigated the concern of common-method bias. The results of Experiment 2 replicated the effects of several existing anomalies, which demonstrates that the difference- comparing process can explain most of such anomalies, except for the sign and speedup/delay effects.

In summary, the results of the four experiments showed that the dimensional difference-comparing is a key process but not the only psychological process of intertemporal choice. The results of our study deepened our understanding of the mechanisms underlying intertemporal choice and added important procedural evidence to current priority models.

Key words: intertemporal choice, priority, tradeoff model, equate-to-differentiate theory, process test