The effects of task unpacking on time prediction: The role of future boundaries and thought focus

doi:10.3724/SP.J.1041.2025.0207

Abstract

Abstract: People often need to predict how long tasks will take to complete. However, due to cognitive stinginess when tackling problems, individuals frequently exhibit irrational decision-making bias in planning long-term goals, leading to underestimations of task completion time, such as planning fallacy. A comparison between the theory of planning fallacy and existing research suggests that this bias may be related to the time clue of the task—the future boundary. Therefore, this study aims to explore the effects of task unpacking on time prediction and its cognitive mechanism under different time clues by setting the future boundary.
To investigate this, three experiments involving 458 college students were conducted, examining the impact of task unpacking and future boundary on time prediction and their cognitive mechanisms. Specifically, Experiment 1 employed a 2 (task unpacking: unpacking/packing) × 2 (future boundary: present/ absent) between-subjects design. The results showed that: (1) When no future boundary was present, the time predictions in the task unpacking condition were significantly shorter than those in the task packing condition. (2) When a future boundary was present, there was no significant difference in time predictions between the task unpacking and packing conditions.
Based on Experiment 1, Experiment 2 further investigated the effect of the time span of the future boundary on time prediction by manipulating the temporal distance between the future boundary and the present. The time span of the future boundary was determined through a pre-experiment, and the formal experiment adopted a 2 (task unpacking: unpacking/packing) × 3 (future boundary time span: short/medium/long) between-subjects design. The results showed that: (1) The longer the time span of the future boundary, the significantly longer the time predictions. (2) Under the condition of short future boundary time span, the time predictions for task unpacking were significantly longer than those for task packing. Under the condition of long future boundary time span, the time predictions for task unpacking were significantly shorter than those for task packing. There was no significant difference between task unpacking and packing under a medium time span of the future boundary.
On the basis of Experiment 2, Experiment 3 further explored the cognitive mechanism underlying the effects of future boundary time span on time prediction under task unpacking condition. A single factor two-level (future boundary time span: short/ long) between-subject design was used. The results revealed that: (1) In the short time span condition, participants focused more on the plan, while in the long time span condition, they considered obstacles more frequently. (2) Thought focus partially mediated the effect of the future boundary time span on time prediction. When the future boundary time span was shorter, participants paid more attention to the task execution plan, resulting in lower time predictions. Conversely, when the future boundary time span was longer, participants focused more on potential obstacles, leading to longer time predictions.
The findings of this study indicate that: (1) Task unpacking influences time prediction. (2) When the future boundary time span is longer, task unpacking exhibits a contraction effect; when the future boundary time span is shorter, it shows an expansion effect. (3) Under the task unpacking condition, the longer the future boundary time span, the more people tend to focus on obstacles, resulting in longer time predictions; the shorter the future boundary time span, the more people tend to focus on the plan, leading to shorter time predictions. Thought focus partially mediates the effect of future boundary time span on time prediction.

Key words: time prediction, task unpacking, future boundary, thought focus

SHI Zifu, XIA Biqi, LIU Xin, CHEN Huohong, JIN Ziyang, PENG Lingyi. (2025). The effects of task unpacking on time prediction: The role of future boundaries and thought focus. Acta Psychologica Sinica, 57(2), 207-217.

References

[1] Bonaccorsi A., Apreda R., & Fantoni G. (2020). Expert biases in technology foresight. Why they are a problem and how to mitigate them.Technological Forecasting and Social Change, 151, 119855.
[2] Buehler, R., & Griffin, D. (2003). Planning, personality, and prediction: The role of future focus in optimistic time predictions.Organizational Behavior and Human Decision Processes, 92(1-2), 80-90.
[3] Buehler R., Griffin D., Lam K. C. H., & Deslauriers J. (2012). Perspectives on prediction: Does third-person imagery improve task completion estimates? Organizational Behavior and Human Decision Processes, 117(1), 138-149.
[4] Buehler R., Griffin D., & Peetz, J. (2010). The planning fallacy: Cognitive, motivational, and social origins. In M. P. Zanna & J. M. Olson (Eds.), Advances in experimental social psychology (Vol. 43, pp. 1-62). Academic Press.
[5] Buehler R., Griffin D., & Ross M. (1994). Exploring the “planning fallacy”: Why people underestimate their task completion times.Journal of Personality and Social Psychology, 67(3), 366-381.
[6] Burt, C. D. B., & Kemp, S. (1994). Construction of activity duration and time management potential.Applied Cognitive Psychology, 8(2), 155-168.
[7] Byram, S. J. (1997). Cognitive and motivational factors influencing time prediction.Journal of Experimental Psychology: Applied, 3(3), 216-239.
[8] Dai H., Milkman K. L., & Riis J. (2014). The fresh start effect: Temporal landmarks motivate aspirational behavior.Management Science, 60(10), 2563-2582.
[9] Dunning, D. (2007). Prediction: The inside view. In E. T. Higgins & A. Kruglanski (Eds.), Social psychology: Handbook of basic principles.(2nd ed., pp. 69-90). Guilford.
[10] Fang J., Wen Z. L., & Zhang M. Q. (2017). Mediation analysis of categorical variables.Journal of Psychological Science, 40(2), 471-477.
[方杰, 温忠麟, 张敏强. (2017). 类别变量的中介效应分析. 心理科学, 40(2), 471-477.]
[11] Faul F., Erdfelder E., Lang A. G., & Buchner A. (2007). G* Power 3: A flexible statistical power analysis program for the social, behavioral, and biomedical sciences.Behavior Research Methods, 39(2), 175-191.
[12] Feng, Y. T., & Huang, X. T. (2015). The effects and mechanism of task characters on the estimation of task duration in the future.Advances in Psychology, 5(10), 571-579.
[冯彦添, 黄希庭. (2015). 任务性质对未来任务时间估计的影响及其理论机制. 心理学进展, 5(10), 571-579.]
[13] Fischhoff B., Slovic P., & Lichtenstein S. (1978). Fault trees: Sensitivity of estimated failure probabilities to problem representation.Journal of Experimental Psychology: Human Perception and Performance, 3(4), 330-334.
[14] Forsyth, D. K. (2004). An investigation into expected duration estimation as used as part of the time management process (Unpublished doctorial dissertation). University of Canterbury, Christchurch.
[15] Forsyth, D. K., & Burt, C. D. B. (2008). Allocating time to future tasks: The effect of task segmentation on planning fallacy bias.Memory & Cognition, 36(4), 791-798.
[16] Goswami, I., & Urminsky, O. (2020). More time, more work: How time limits bias estimates of task scope and project duration.Judgment & Decision Making, 15(6), 994-1008.
[17] Hadjichristidis C., Summers B., & Thomas K. (2014). Unpacking estimates of task duration: The role of typicality and temporality.Journal of Experimental Social Psychology, 51, 45-50.
[18] Halkjelsvik, T., & Jørgensen, M. (2012). From origami to software development: A review of studies on judgment-based predictions of performance time.Psychological Bulletin, 138(2), 238-271.
[19] Halkjelsvik, T., & Jørgensen, M. (2018). Time prediction methods and principles.Time Predictions, 5, 81-102.
[20] Halkjelsvik T., Jørgensen M., & Teigen K. H. (2011). To read two pages, I need 5 minutes, but give me 5 minutes and I will read four: How to change productivity estimates by inverting the question.Applied Cognitive Psychology, 25(2), 314-323.
[21] Hu C. P., Kong X. Z., Wagenmakers E. -J., Ly A., & Peng K. P. (2018). The Bayes factor and its implementation in JASP: A practical primer. Advances in Psychological Science, 26(6), 951-965.
[胡传鹏, 孔祥祯, Wagenmakers, E. -J., Ly A., 彭凯平. (2018). 贝叶斯因子及其在JASP中的实现.心理科学进展, 26(6), 951-965.]
[22] Huang X. T., Li B. Y., & Zhang Z. J. (2003). The research of the range-synthetic model of temporal cognition.Journal of Southwest China Normal University (Humanities and Social Sciences Edition), 29(2), 5-9.
[黄希庭, 李伯约, 张志杰. (2003). 时间认知分段综合模型的探讨.西南师范大学学报(人文社会科学版), 29(2), 5-9.]
[23] Kahneman, D., & Tversky, A. (1979). Prospect theory: An analysis of decision under risk.Econometric, 47, 263-291.
[24] Kanten, A. B. (2011). The effect of construal level on predictions of task duration.Journal of Experimental Social Psychology, 47(6), 1037-1047.
[25] Kelly, W. E. (2002). Harnessing the river of time: A theoretical framework of time use efficiency with suggestions for counselors. Journal of Employment Counseling, 39(1), 12-21.
[26] Kim, B. K., & Zauberman, G. (2009). Perception of anticipatory time in temporal discounting.Journal of Neuroscience Psychology & Economics, 2(2), 91-101.
[27] Kruger, J., & Evans, M. (2004). If you don't want to be late, enumerate: Unpacking reduces the planning fallacy. Journal of Experimental Social Psychology, 40(5), 586-598.
[28] LeBoeuf, R. A., & Shafir, E. (2009). Anchoring on the “here” and “now” in time and distance judgments. Journal of Experimental Psychology.Learning, Memory, and Cognition, 35(1), 81-93.
[29] Liberman, N., & Trope, Y. (1998). The role of feasibility and desirability considerations in near and distant future decisions: A test of temporal construal theory.Journal of Personality and Social Psychology, 75(1), 5-18.
[30] Liu, Y., & Sun, Y. (2016). Time unpacking effect and its impact on intertemporal decision making.Acta Psychologica Sinica, 48(4), 362-370.
[刘扬, 孙彦. (2016). 时间分解效应及其对跨期决策的影响.心理学报, 48(4), 362-370.]
[31] Miaolei J., Xiuping L., & Aradhna K. (2020). Contraction with unpacking: When unpacking leads to lower calorie budgets.Journal of Consumer Research, 46(5), 853-870.
[32] Miletić, S., & Maanen, L. V. (2019). Caution in decision-making under time pressure is mediated by timing ability.Cognitive Psychology, 110, 16-29.
[33] Moher, E. (2012). Tempering optimistic bias in temporal predictions: The role of psychological distance in the unpacking effect (Unpublished doctorial dissertation). University of Waterloo, Ontario, Canada.
[34] Nussbaum S., Liberman N., & Trope Y. (2006). Predicting the near and distant future.Journal of Experimental Psychology: General, 135(2), 152-161.
[35] Peetz J., Buehler R., & Wilson A. (2010). Planning for the near and distant future: How does temporal distance affect task completion predictions? Journal of Experimental Psychology, 46(5), 709-720.
[36] Peetz, J., & Wilson, A. E. (2013). The post-birthday world: Consequences of temporal landmarks for temporal self-appraisal and motivation. Journal of Personality and Social Psychology, 104(2), 249-266.
[37] Redaelli, I., & Carassa, A. (2018). New perspectives on plans: Studying planning as an instance of instructed action.Computer Supported Cooperative Work, 27(1), 107-148.
[38] Redden, J. P., & Frederick, S. (2011). Unpacking unpacking: Greater detail can reduce perceived likelihood.Journal of Experimental Psychology General, 140(2), 159-167.
[39] Roy M. M., Burns T., & Radzevick J. R. (2019). Unpacking, summing and anchoring in retrospective time estimation. Acta Psychologica, 192, 153-162.
[40] Roy, M. M., & Christenfeld, N. J. (2008). Effect of task length on remembered and predicted duration.Psychonomic Bulletin & Review, 15(1), 202-207.
[41] Roy M. M., Christenfeld N. J., & McKenzie C. R. (2005). Underestimating the duration of future events: Memory incorrectly used or memory bias? Psychological Bulletin, 131(5), 738-756.
[42] Shmueli O., Pliskin N., & Fink L. (2016). Can the outside-view approach improve planning decisions in software development projects? Information Systems Journal, 26(4), 395-418.
[43] Siddiqui R. A., May F., & Monga A. (2014). Reversals of task duration estimates: Thinking how rather than why shrinks duration estimates for simple tasks, but elongates estimates for complex tasks.Journal of Experimental Social Psychology, 50(1), 184-189
[44] Tonietto, G. N., & Malkoc, S. A. (2016). The Calendar Mindset: Scheduling takes the fun out and puts the Work In.Journal of Marketing Research, 53(6), 922-936.
[45] Tonietto G. N., Malkoc S. A., & Nowlis S. M. (2019). When an hour feels shorter: Future boundary tasks alter consumption by contracting of time.Journal of Consumer Research, 45(5), 1085-1102.
[46] Trope, Y., & Liberman, N. (2003). Temporal construal.Psychological Review, 110(3), 403-421.
[47] Tu, Y., & Soman, D. (2014). The Categorization of time and its impact on task initiation.Journal of Consumer Research, 41(3), 810-822.
[48] Tversky, A., & Koehler, D. J. (1994). Support theory: A nonextensional representation of subjective probability.Psychological Review, 101(4), 547-567.
[49] Van Boven, L., & Epley, N. (2003). The unpacking effect in evaluative judgments: When the whole is less than the sum of its parts.Journal of Experimental Social Psychology, 39(3), 263-269.
[50] Wagenmakers E. -J., Marsman M., Jamil T., Ly A., Verhagen J., Love J., … Morey R. D. (2018). Bayesian inference for psychology. Part II: Example applications with JASP.Psychonomic Bulletin & Review, 25(1), 58-76.
[51] Wang P., Wang X. T., Gao J., Li X. L., & Xu J. (2019). Adaptive time management: The effects of death awareness time perception and intertemporal choice.Acta Psychologica Sinica, 51(12), 1341-1350.
[王鹏, 王晓田, 高娟, 黎夏岚, 徐静. (2019). 适应性时间管理:死亡意识对时间知觉和跨期决策的影响.心理学报, 51(12), 1341-1350.]
[52] Weick, M., & Guinote, A. (2010). How long will it take? Power biases time predictions.Journal of Experimental Social Psychology, 46(4), 595-604.
[53] Wetzels R., Matzke D., Lee M. D., Rouder J. N., Iverson G. J., & Wagenmakers E. -J. (2011). Statistical evidence in experimental psychology: An empirical comparison using 855t tests. Perspectives on Psychological Science, 6(3), 291-298.
[54] Yoon, J. (2020). Extension Request: An underexplored response to deadlines (Unpublished doctorial dissertation). Harvard University Graduate School of Arts and Sciences.
[55] Zhu D., Li X., Yang S., & Xie X. (2019). More accurate or less accurate: How does maximization orientation affect task completion predictions? Personality and Individual Differences, 137, 173-183.