The impact of stress and failure on effort and snack choices

Participants of the study are asked to complete two experimental sessions at least one week apart. The experiment will follow a 2x2 experimental design resulting in four experimental conditions. The experimental conditions are randomized at the participant level and introduce random variation in the decision environment in which participants complete three outcome tasks: (1) cost of exerting effort, (2) effort choices, and (3) snack choices. Specifically, the experimental conditions vary the levels of stress and failure participants experience when making these decisions.

The first experimental variation (Treatment 1) is in the timing of the stress task. At the beginning of the experiment sessions and therefore before the outcome tasks, participants are asked to either complete an incentivized cognitive task aimed at inducing mild stress (stress session) or to read three short texts and answer questions about the texts (control session). Each participant will be asked to complete one stress and one control session: if their first session was assigned to the stress condition, their second session will be assigned to the control condition (and vice versa).

The second experimental variation (Treatment 2) is in the feedback given during the second session. The incentive structure for the stress task involves a (potential) deduction from participants’ pay-off if they perform below an unknown threshold. Prior to completing the economic decision tasks during their second visit, participants receive feedback regarding their performance in the stress task relative to this threshold. Participants are randomly assigned either to the “feedback with a low threshold” condition (success condition) or the “feedback with a high threshold” condition (failure condition).

This design allows us to compare the outcomes in different decision environments, both between different participants and within the same participant across the two sessions.

2023-02-27

2023-05-31

The primary endpoints are:
1 – Number of unhealthy snacks chosen in pairwise choices
2 – Cost of engaging in real-effort tasks
3 – Cost of engaging in a cognitive effort task
4 – Performance in the real effort task

1 – Number of unhealthy snacks (higher added sugars, saturated fat, sodium content, and lower dietary fiber content) chosen in 20 pairwise choices between different snacks
2 – Cost of engaging in real effort tasks (the slider task and the counting zeros task): minimum amount accepted to not enter a real effort task with a piece-rate payoff
3 - Cost of engaging in a cognitive effort task, collected only in session 2: minimum amount accepted to not enter a cognitive effort task that gives a payoff to participants
4 – Performance in the real effort task: number of completed sliders and number of correct responses in the counting task

Participants are asked to attend two experimental sessions, approximately one week apart. During both sessions, they are asked to complete incentivized pairwise choices between different snacks, four healthy and four unhealthy. They are then asked to state the minimum payment they would need to be offered to not enter two effort tasks: 1) a real effort task; 2) a cognitive effort task [only in the second session]. The real effort task consists of two parts: two minutes of a slider task, in which participants are required to move as many sliders as possible to a specified position; and two minutes of a counting task, in which participants are asked to count the number of zeros in several matrixes of zeros and ones. Finally, they are asked to perform the real effort task, unless the minimum payment they require not to complete the real effort tasks is lower than 1 cent. In this case, participants will receive 1 cent and not complete the real effort task but will read a short text.

Using a 2x2 experimental design, the decision environment is exogenously varied between participants as well as between the first and second sessions attended by each participant. First, participants are assigned to complete an incentivized cognitive task aimed at inducing mild stress, either at the beginning of the first or the second session they attend. The stress task was adapted from a previous experimental study (Vitt et al., 2021) and has already been tested and validated using an online experiment (RCT ID: AEARCTR-0005946). This first experimental treatment introduces exogenous variation in the acute stress levels during the two sessions. The second experimental treatment introduces an additional element in the incentive structure for the stress task, a deduction from participants’ pay-off if they perform below an unknown threshold. Before the snack and effort decision-making tasks in the second session they attend, participants receive feedback about their performance relative to the threshold. The threshold level faced is varied by the second experimental treatment. Specifically, participants may face a low threshold level and receive success feedback or a high threshold level and receive failure feedback. This second experimental treatment introduces exogenous variation in perceived success or failure during the second session and has already been tested and validated using an online experiment (RCT ID: AEARCTR-0005946).

Subjects will receive a participation fee at the end of their second session. They will be paid a participation fee, and a varying amount either based on their performance in the stress task or based on their choices in one of the decision-making tasks. Finally, they receive a snack based on one of the pairwise choices in each session.

Randomization is done using the online platform hosting the experiment sessions (Qualtrics).

Individual

No

240-300 participants

Minimum of 60*4=240 participants, maximum of 75*4=300 participants

60 to 75 participants

0.21 - 0.3 standard deviations for the impact of stress, 0.55 - 0.61 standard deviations for the impact of failure, and 0.75 - 0.84 standard deviations for the interaction of stress and failure.

Power calculation