Experimental Design Details
The experiment consists of a hypothetical meal scenario that places subjects in a restaurant situation, with a friend. Subjects were asked to choose between two meals (creamy shrimp pasta or meatballs and pasta), shown on pictures. They were informed one meal contains 500 calories and the other 1000 calories, but that they would not know which one, unless they got calorie information.
The experiment entailed three treatments -- one where subjects received no information on calorie content in their food, one where they did receive the information, and one where they could chose to either obtain or avoid the information. Before being randomized into these treatments, subjects answered a set of questions common to all subjects.
All subjects were asked to rate the expected taste of both meals from 1=very bad to 5=very good.
To enable us to measure how subjects’ change in demand for a high calorie meal when provided calorie information, we designed the experiment such that the favorite meal chosen by a subject was always be the high-calorie meal, i.e., if a subject chose shrimp (meatballs) as their favorite meal, they were directed into a version of the experiment survey where shrimp (meatballs) was the high calorie meal.
Subjects were asked about how they would feel about getting calorie information in this meal situation. They could state both positive and negative emotions along a 7 grade scale (1=very good, 7=very bad and 4=neutral, as implied by smiley faces).
Subjects were asked about their preference for calorie information in this particular meal situation.
Subjects’ Willingness to pay (WTP) for calorie information was thereafter elicited using a multiple-price-list, entailing pairwise choices of no information/information, while varying meal prices (e.g., “Which would you prefer? (i) Calorie information + pay $12 for a meal at the restaurant, (ii) No calorie information + pay $12.50 for a meal at the restaurant,” etc.).
Subjects were thereafter asked about their marginal WTP for their favorite meal (i.e., the high calorie meal). At this stage of the survey, subjects were also randomized into one of three treatment groups – (1) exogenous calorie information, (2) endogenous calorie information, (3) no calorie information. Subjects in the exogenous information treatment were informed on the calorie content of the meals (1000 calories in their favorite meal, 500 in the other meal). Subjects in the endogenous information treatment were asked to choose if they wanted costless calorie content of the meals before stating their marginal WTP for the high calorie meal. Subjects in the no information treatment were given no calorie information before stating their marginal WTP for the high calorie meal.
Finally, all subjects answered a battery of questions measuring eating self-control, general health and health attitudes, as well as common demographics, eating self-control, age, and income.