Transparency is intimately linked to debates about the ethics, political legitimacy and effectiveness of nudging. This paper provides an overview of empirical studies investigating how changes in the transparency of a nudge affect people's choices and evaluations of the nudge. The author concludes that the present literature provides generally consistent evidence supporting that the effectiveness of a nudge does not decrease when choosers are given good opportunity to detect and understand the influence it might have on their choices. However, several conceptual and methodological issues are identified, significantly limiting the scope of the conclusions that can be drawn. The limitations are discussed and organized into six themes, with recommendations provided for how future research may address them.
