ISSN 0439-755X
CN 11-1911/B

心理学报 ›› 2016, Vol. 48 ›› Issue (4): 362-370.doi: 10.3724/SP.J.1041.2016.00362

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  1. (1中国科学院心理研究所行为科学重点实验室, 北京 100101) (2中国科学院大学人文学院, 北京 100049)
  • 收稿日期:2015-05-04 出版日期:2016-04-25 发布日期:2016-04-25
  • 通讯作者: 孙彦, E-mail:
  • 基金资助:


Time unpacking effect and its impact on intertemporal decision making

LIU Yang1,2; SUN Yan1   

  1. (1 Key Laboratory of Behavioral Science, Institute of Psychology, Chinese Academy of Sciences, Beijing 100101, China)
    College of Humanities & Social Sciences, University of Chinese Academy of Science, Beijing 100049, China)
  • Received:2015-05-04 Online:2016-04-25 Published:2016-04-25
  • Contact: SUN Yan, E-mail:


本文基于经典的分解效应, 提出并证实了一种影响人们判断与决策中时间知觉的新因素——时间分解效应。共包括两个研究, 分别在“时间够用”判断与跨期决策中检验了该效应的存在性与稳固性。实验结果表明:(1)相比未分解条件, 分解条件下的被试判断给定时间内完成某项任务的时间更够用, 即时间知觉更长。该效应受到任务难度的调节, 在较简单的任务中时间分解效应更显著; (2)在跨期决策中, 分解操纵增大了人们对较大较远的收益(larger & later, LL)选项中时间延迟的知觉, 证实了时间分解效应。此外, 还发现时间分解效应会导致人们在跨期决策中更偏好较小较近的收益(smaller & sooner, SS)选项, 对时间延迟的知觉中介了这一过程。总之, 本研究不仅在理论上提出了一种新的分解效应, 同时对现实生活中的决策(如计划制定等)有重要的应用价值。

关键词: 分解效应, 时间知觉, 时间判断, 跨期决策


Time perception/judgment is relevant to everyone and is an integral part of decision making, because any meaningful choices are embedded in a temporal context. The unpacking effect (Tversky & Koehler, 1994) in probability judgment refers to a phenomenon where “unpacking” an event could increase the subjective probability judgment of the event. Given the similarity of time and probability in intertemporal and risky decision making and based on the results of plan fallacy research, we conject that the unpacking effect may also be detected in time perception/judgment. Unlike previous research that focused on the unpacking manipulation of some events, we only used pure manipulation on a time interval. We named this phenomenon the time unpacking effect, where a time interval is presented in an unpacked rather than compact way, thus lengthening subjective time perception. In this research, two studies explored the time unpacking effect in judgment and intertemporal decision making, and the impact the effect has on intertemporal decision making.

Study 1 tested this effect in temporal judgment of whether a given time is sufficient to complete a task. Hypothesis 1a states that people in the unpacking condition compared with those in the packed condition will have higher scores, meaning they will perceive the time period as longer. Based on previous research, we formulated hypothesis 1b stating that task difficulty will affect the time unpacking effect. The experiment used a between-subjects design, where 124 participants were randomly assigned to a packed or unpacked condition and were presented with two scenarios within which tasks of varying difficulty were presented and asked to finish the corresponding computerized questionnaires. As a control factor we measured the participants’ degree of busyness during the specified time periods. A mixed design MANOVA revealed that the interaction of condition-by-difficulty degree was significant, F(1, 120) = 5.14, p < 0.05. Furthermore, in the second scenario, which had a lower degree of difficulty, the unpacking manipulation significantly influenced the participants’ time judgment (t(122) = 2.70, p < 0.01), while in the first scenario, the effect was not significant (t(122) = 0.77, p > 0.05). These results supported hypotheses 1a and 1b.

Study 2 tested the time unpacking effect and explored its influence on intertemporal decision making. Hypothesis 2a states that participants in the unpacking condition perceive time delay as longer in the larger but later (LL) option of intertemporal choice, and thus prefer the smaller but sooner (SS) option compared with participants in the packed condition. Hypothesis 2b states that time perception of delay in the LL option mediates the effect of unpacking manipulation on intertemporal choice. The design and procedure were the same as in study 1. A total of 124 participants finished one of two versions of the intertemporal choice computerized questionnaire containing two scenarios. MANOVA analysis found that in both scenarios, people in the unpacking condition perceived a longer time delay (first scenario: F1(1, 98) = 9.03, p1 < 0.01; second scenario: F2(1, 98) = 6.54, p2 < 0.05). They also preferred the SS option in intertemporal decision making, F1(1, 98) = 13.82, p1 < 0.001 and F2(1, 98) = 4.47, p2 < 0.05 in the first and second scenarios, respectively. These results supported hypothesis 2a. Meanwhile, bootstrap mediating analysis supported hypothesis 2b indicating that time perception of delay mediated the influence of unpacking manipulation on intertemporal choice at 90% confidence interval in the first scenario (0.4660, 0.0220) and 95% confidence interval in the second scenario (0.4621, 0.0151).

This research identified a new influencing factor in judgment and decision making called the time unpacking effect, and implemented two studies to demonstrate its robustness. Using either an indirect (study 1) or direct (study 2) way to measure time perception substantiated this effect. Our time unpacking effect could be explained by support theory, specifically the attentional explanation. Compared with other influencing factors of time perception, the time unpacking effect is easier to manipulate, therefore it has more practical value in our daily lives.

Key words: unpacking effect, time perception, temporal judgment, intertemporal decision making