Experimental Design
In the laboratory experiment, participants will repeatedly indicate their WTP for product pairs in three joint evaluations, where two products are presented next to each other. Participants indicate their WTP for both products separately, resulting in six WTP entries per participant. Across three joint evaluations, the food products will systematically vary in the production method (conventional versus organic) and in the coloring technique (opaque versus marbled). In one joint evaluation, the two products only vary in the production method (simple comparison). Participants state their WTP for conventional marbled colored eggs and organic marbled colored eggs, allowing clear attribution of preferences to the production method. In two joint evaluations, both production method and painting type vary (complex comparison). In one complex joint evaluation, participants have to indicate their WTP for conventional marbled colored eggs and organic opaque colored eggs. In the other complex joint evaluation, participants have to indicate their WTP for organic marbled colored eggs and conventional opaque colored eggs. Since both attributes differ, any preference cannot be clearly attributed to a preference for a production method or a painting type. To minimize order and consistency effects, participant complete a filler task (identifying the most frequently occurring letter in a sequence) between each joint evaluation. In addition, the order of the three joint evaluations is randomized, ensuring that each appears equally likely as the first comparison. This design allows for between-subject analysis as a robustness check.
In addition, we aim to examine whether the presence of implicit and explicit preferences are influenced by the contextual setting, specifically, how participants behave when their WTPs are made private versus public. To explore this, we will use a between-subject design with two treatments: 1) In the public treatment, at the end of the experiment, one joint evaluation is randomly selected, and participants’ stated WTP for both products is disclosed to the other participants in the same session. Participants are informed at the beginning that any of their three joint evaluations could be selected and made visible. In the private treatment, the procedure is identical, except that participants' responses remain anonymous. Participants are informed that we use a double-blind design for the payout - a person in another room will prepare participants’ payout (product and/or cash) in an envelope and leave the room after everything is prepared. Participants will collect their payout autonomously without anyone else knowing what they received.
Furthermore, we elicit beliefs on descriptive and injunctive social norms. Belief elicitation will be incentivized and takes place after participants stated their WTP for all products. Participants will also complete a survey on self-report scales (e.g., social image concerns, self-image concerns, liking of products, attitude towards organic, frequency of buying organic, reasons to buy organic, barriers to buy organic, estimating food market prices, whether they know people participating in the same session) and answer demographic questions. We will examine whether intransitive choices are influenced by factors like social signaling, self-signaling and beliefs on social norms. Further, we will also measure reaction time in the joint evaluations, that is, the time participants need to indicate their WTP for both products within a joint evaluation.
Hypotheses
Dilution:
H1: Participants have explicit preferences for organic eggs and implicit preferences for conventional eggs.
H1a: Participants have a higher WTP for organic marbled colored eggs when they are compared to conventional marbled colored eggs (simple comparison) than when they are compared to conventional opaque colored eggs (complex comparison).
H1b: Participants have a higher WTP for conventional marbled colored eggs when they are compared to organic opaque colored eggs (complex comparison) than when they are compared to organic marbled colored eggs (simple comparison).
Signaling:
H2: Participants’ differences between implicit and explicit preferences are stronger in the public treatment than in the private treatment.
H2a: There is an interaction between dilution and decision context such that participants decrease their WTP for organic marbled colored eggs from the simple comparison to the complex comparison stronger when they are in the public treatment than when they are in the private treatment.
H2b: There is an interaction between dilution and decision context such that participants increase their WTP for conventional marbled colored eggs from the simple comparison to the complex decision stronger when they are in the public treatment than when they are in the private treatment.
Cunningham, T., & de Quidt, J. (2024). Implicit Preferences. https://jondequidt.com/pdfs/paper_implicit.pdf