Being transparent about personalization: The case of personalized digital "just-in-time" nudges for healthier food choice

Digital "just-in-time" (JIT) nudging is a potentially promising strategy to promote healthier online food choices: nudges can intervene when one adds an unhealthy product to their virtual shopping basket and can be personalized to match users' preferences or motivations. However, both nudging and personalization raise (ethical) concerns, as disclosing the presence and/or purpose of (non)personalized nudges is necessary for users to make an informed decision but might lead to counterproductive effects. We shed light on this tension by (1) examining the role of transparency in moderating the impact of personalized (versus non-personalized) digital JIT nudges on healthier food choices, and (2) exploring its underlying mechanisms (i.e., increased perceptions of nudge acceptability, experienced autonomy, decreased psychological reactance). In a 2 (Nudge Personalization: Non-personalized vs. Personalized) by 2 (Nudge Transparency: Non-transparent vs. Transparent) between-subjects lab experiment, 200 healthy participants completed an online grocery shopping task on a mock supermarket app. Results showed that nudge personalization and transparency did not lead to healthier food choices. Furthermore, transparency did not influence perceptions of nudge acceptability, experienced autonomy, and psychological reactance regarding personalized JIT nudges, nor did it compromise these outcomes in non-personalized counterparts. We conclude that, while we did not find an added benefit of nudge personalization for healthier online food choices, there was no indication that transparency would be detrimental to the effectiveness nor perceptions of digital JIT nudges in general, which has implications for design and policy concerning nudging in practice.