Unpacking transparency in nudging: the impact of different disclosure messages on nudge effectiveness and perceived autonomy

Recent developments in behavioural public policy emphasise the potential of transparent nudging interventions, such as nudge+ or boosts, to engage people with their decisions. However, the current state of research on transparent nudging is fraught with methodological critiques, and only a handful of studies examine differences between types of transparency messages or ‘disclosures’. Using a vignette survey experiment ( n = 1916), we measure the influence of transparency, operationalised through different types of disclosures, on both the effectiveness of the nudging technique and the perceived autonomy of those subjected to the nudge. We employ a salience nudge to promote sustainable food choices and present four different disclosures. Results indicate that, while the nudge proved effective in promoting sustainable food choices, the disclosures neither enhanced nor reduced its effectiveness. At the same time, the nudge led to a small but significant decrease in perceived autonomy, which the disclosures did not offset. Overall, differences between the types of disclosures were not substantial enough to yield significant effects in either behavioural outcomes or perceived autonomy. These findings suggest that while disclosures can be applied to increase transparency without compromising nudge effectiveness, they are not sufficient to mitigate concerns about autonomy in nudging interventions.