Default Nudge Efficacy in Lower Versus Higher SEP-Groups: Two Online Supermarket Experiments

Objective: Nudging is commonly assumed to be particularly effective among subpopulations with lower socio-economic position (SEP) hence to combat health disparities, but empirical evidence is scarce. In two studies, we examined the efficacy of a default nudge in stimulating healthy food choices and whether this effect is moderated by SEP using different SEP-operationalizations. Methods: In both online experiments (performed in 2022 and 2024), a default nudge stimulating healthy food choices was compared to a control condition (without default nudge) in a hypothetical online supermarket setting among UK participants with lower and higher SEP. Study 2 involved a more realistic supermarket setting where the presence of price information was manipulated. SEP-indicators (education, subjective social status and income) and related SEP-variables (resource availability, perceived stress and financial scarcity) were measured. Results: Across the two studies, we found that the default nudge is efficacious in stimulating healthy choices. This effect was not consistently moderated by SEP, with the effect being present among both lower and higher SEP groups. Study 2 further demonstrates that these effects are not impacted by the presence of price information. Conclusions: These results imply that although the default nudge is not more effective among people with lower SEP, this technique seems at least to also benefit the group that needs effective strategies the most, even when processing additional price information. However, future studies on nudge effects in real-life settings, where (financial) factors matter, are needed to learn whether default nudges can actually benefit people with lower (versus higher) SEP.