Experimental Design
Main treatment: Participants in the main treatment complete six parts (Trial and Parts 1–5). Participants are informed in the instructions that the true task benefit lies between 50 and 150 points per solved encryption task and is the mean of a distribution with 150 realizations, but they do not know that this underlying distribution is left-skewed with a true mean of 120.
• Trial: Before starting the trial round participants are asked about their prior belief about the true task benefit (θ0) only knowing that the payoff per task is between 50 and 150 points. Afterwards participants complete a 8-minute trial round of the encryption task (a0) to become familiar with the task itself and their task-specific effort costs.
• Part 1: Participants (i) are reminded of their previous number of solved encryption tasks, report (ii) their ideal number of solved encryption tasks for various hypothetical levels of the unknown task benefit, and (iii) their predicted number of solved tasks for those benefit levels. There is a two percent probability that participants actually have to work on as many encryption tasks in part 5 as they stated as ideal for the true task benefit level in part 1. After stating their ideal and predicted number of solved tasks, participants work on the encryption task for a maximum of 8 minutes (a1) or may instead choose to stop working and spend the remainder of the 10 minutes on an outside option (a distraction task such as using their cellphone with low compensation).
• Parts 2–4: Each of these parts follows an identical structure. Participants (i) are reminded of their previous number of solved tasks, (ii) are asked to state their updated belief about the task benefit (θ1, θ2, θ3), (iii) are shown a signal about the true task benefit (s1, s2, s3),—specifically, 50 out of the 150 possible benefit realizations (“balls”) drawn without replacement that are displayed for approximately 10 seconds—and (iv) again choose between working on the encryption task (a2, a3, a4) or the outside option for 8 minutes. Across Parts 2–4, participants see all 150 realizations once, allowing them to progressively learn the true value of the task benefit.
• Part 5: Participants (i) are reminded of their past action, (ii) state their final belief about the true task benefit (θ4), (iii) report their ideal and (iv) predicted number of solved tasks for what they believe the task benefit is. Then, (v) they complete a final 8-minute work period (a5), including the possibility of spending part of the time on the outside option. With two percent probability each, participants do not do as many tasks as they want in Part 5, but they have to do as many as they stated as ideal for the true task benefit level in either the first part or for what they believe the task benefit is in the fifth part.
After each part, participants complete a short “buffer” questionnaire to introduce a break between the different parts to foster forgetting of the precise signals on task benefit they have seen. The different questionnaires cover sociodemographic characteristics, last math grade in school, the digit span subtest by Wechsler (1939), the Big Five personality traits from John et al. (1991), measures of economic preferences from the Global Preferences Survey by Falk et al. (2018), the Brief Self-Control Scale from Tangney et al. (2004), an average calculation task, and questions regarding the experiment asking how good they remember the “balls” from the signals, and if they have taken a screenshot of them. Lastly, we included a hard to answer mathematical task to be able to detect AI agents.
Control treatment: The control treatment is structured in exactly the same way as the main treatment, except for the following difference. Participants know the exact, fixed task benefit of 120 points per correctly solved encryption task right from the beginning (already before the trial part). There is still a fundamental about which they are receiving signals and they have to report their beliefs about. However, the fundamental is unrelated to the task benefit. The signal structure and the belief elicitation process are identical to the main treatment. The purpose of the control treatment is to show (i) that / to which extent people can update beliefs correctly over time if there is “no reason to trick themselves” (i.e., to update too little on the task benefit to justify the own low performance in the encryption task) and (ii) that people possibly work harder if they cannot trick themselves (caveat: according to DellaVigna and Pope (2022), we often see maximum effort provision in real effort task experiments like ours that is largely insensitive to effort costs and benefits which is the reason why we consider beliefs as our key dependent variable). The control treatment also shows whether and how the cost of effort might change across the parts, allowing to control for a potential decrease in effort over time simply due to participants getting tired.
DellaVigna, S. & Pope, D. (2022). Stability of experimental results: Forecasts and evidence. American Economic Journal: Microeconomics, 14(3), 889-925.
Falk, A., Becker, A., Dohmen, T., Enke, B., Huffman, D. & Sunde, U. (2018). Global Evidence on Economic Preferences, The Quarterly Journal of Economics 133(4), 1645–1692, https://doi.org/10.1093/qje/qjy013.
John, O. P., Donahue, E. M., & Kentle, R. L. (1991). Big Five Inventory (BFI) [Database record]. APA PsycTests.
Tangney, J. P., Baumeister, R. F., & Boone, A. L. (2004). High self-control predicts good adjustment, less pathology, better grades, and interpersonal success. Journal of Personality 72, 271–322.
Wechsler, D. (1939). The measurement of adult intelligence. Williams & Wilkins Co. https://doi.org/10.1037/10020-000.