Mechanisms between Time Scarcity and Healthiness of Food Choices: Evidence from a Lab Experiment

The lab experiment consists of three parts: 1) Snack selection, 2) Auction, and 3) Survey questionnaire. The first part of the experiment (snack selection) will follow a 3x2 experimental design resulting in six experimental conditions, and the second part of the experiment (auction) will have two experimental conditions.

In the first part of the experiment (snack selection), we study the impact of time available to consume a snack on the healthfulness of food choices. Participants in the experiment are offered healthy and unhealthy snack options (food items and beverages) and asked to select the snack which they will consume during a break.
We developed a menu composed of obviously healthy versus unhealthy option pairs (seven food item pairs and three beverage pairs), with products in a pair that have a similar eating time. Participants are asked to select one product in each pair. Only one pair from each of the food item pairs and beverage pairs are then randomly selected, and participants receive their preferred product in the selected pairs. After snack consumption, we also measure food waste to use it as a control.
We randomly assign participants to two time-related treatments: 1) “consumption time” treatment where the time available for snack consumption is short for the treated and long for the control, and 2) “selecting time” treatment where the treated participants are asked to select their snack within 3 seconds for each pair while the controlled participants have no limit to select. For the “consumption time” treatment, we use two means to shorten the time available for snack consumption: 1) Give the treated participants the same amount of time as the control group (20 minutes), but with tasks to do. The tasks we ask the treated to do are solving 50 math problems (2-digit addition and subtraction) and typing a 1-page document. In this case, the cognitive load does not influence the participants’ decisions because the selection is made before performing the given tasks. 2) Give the treated participants a physically shorter amount of time (3 minutes) than the control group to consume the snack.

In the second part of the experiment (auction), we elicit participants’ willingness to pay (WTP) using a sealed-bid second-price auction mechanism introduced by Vickrey (1961). We aim to investigate the impact of preparation time and time pressure when making decisions on the WTP for several food products. We elicit participants’ WTP for foods that differ in two dimensions: (a) time required for preparing the meal: fast versus slow, and (b) healthfulness of the meal: healthy versus unhealthy. This allows us to investigate whether WTP for healthfulness is different for foods with different preparation times. To study the impact of time scarcity during making decisions, we vary the time available for participants to submit their bids with a randomly assigned “bidding time” treatment: the treated participants need to bid on four products within 20 seconds in order to avoid deductions while the controlled participants have no limit to bid.
We auction twelve products in three product categories: soup, oatmeal, and mac & cheese. For each product category, we identified four products that vary in the two dimensions of healthfulness and preparation time. Participants are asked to simultaneously bid on the four products in each product category. Participants can bid up to $20 for each product. The bidder placing the highest bid is the winner and purchases the product at the price corresponding to the second highest bid.

2023-06-10

2023-09-30

1 – Number of unhealthy snacks (higher added sugars, saturated fat, and sodium content) chosen in pairwise choices (seven food item pairs and three beverage pairs)
2 – Amount of time spent selecting the snack from each pair
3 – Willingness to pay for three food products categories (soup, oatmeal, and mac & cheese) divided into four products according to preparation time and healthiness (fast and healthy, fast and unhealthy, slow and healthy, and slow and unhealthy)
4 – Amount of time spent bidding on the four products in each food product category

The experiment will be conducted from June 10, 2023, in the Laboratory for Economics, Management, and Auctions (LEMA) Lab at the Pennsylvania State University. We invite 360-420 subjects to participate in the experiment, expecting 8-16 participants in each session. The lab experiment consists of three parts: 1) Snack selection, 2) Auction, and 3) Survey questionnaire. We make participants select a snack prior to the auction so that cognitive load does not influence their decision on selecting a snack.
In the first part of the experiment, the snack selection, we investigate the relationship between time scarcity and healthfulness of food consumption. We randomly assign the time available to consume a snack and let participants select the snack to consume in our lab.
In the second part, the auction, we study the link between time scarcity and healthfulness of food purchases, and we focus on preparation time as the form of time scarcity in this experimental design. Based on an auction mechanism, we elicit participants’ willingness to pay (WTP) for healthfulness in foods that require different preparation times.
Alternatively, the impact of time on food choices might be mediated by the time available to make the decision. In both parts of the experiment, we randomly vary the time available to state the WTP and to select the preferred snack option. It is possible that with little time to decide, individuals could dismiss the value of the healthy attribute, thus leading to the selection of a less healthy food option.
In the last part of the experiment, participants are asked to answer questions about their sociodemographic characteristics, time uses, and eating habits. Their answers are used to control factors affecting snack selection or WTP for healthfulness other than time to consume, time to decide, and time to prepare.

Randomization is done by the experimental software (oTree).

Randomization for “consumption time” treatment is done at the session level (8 to 16 subjects).
Randomization for the other two treatments (“selecting time” and “bidding time”) is done at the participant level.

Yes

360 to 420 participants

Part 1 (Snack Selection): Minimum of 60*6=360 participants, maximum of 70*6=420 participants Part 2 (Auction): Minimum of 180*2=360 participants, maximum of 210*2=420 participants

Part 1 (Snack Selection): 60 to 70 participants
Part 2 (Auction): 180 to 210 participants