Do nudges make use of automatic processing? Unraveling the effects of a default nudge under type 1 and type 2 processing

Nudges have become increasingly popular among policymakers as a tool to stimulate desirable behavior for individuals or society. One of the most prevailing assumptions of nudges is that they make use of automatic processing. Yet, this assumption has received little attention in experimental research. In two preregistered and high powered studies, we investigated this hypothesized working mechanism by using a nudge that has most typically been described as a Type 1nudge: defaults. In both studies, we used a scenario in which participants could choose from a list of green amenities, which were either preselected (opt-out condition) or not (opt-in condition). In Study 1, we investigated the effectiveness of this default nudge under Type 1 processing by manipulating cognitive load. In Study 2, we investigated its effectiveness under Type 2 processing by explicitly instructing half of the participants to deliberate upon their choice. Both studies revealed strong and robust evidence for the default effect. Study 1 further revealed that this default effect was statistically equivalent under cognitive load. Study 2 revealed that the default effect was not attenuated when participants deliberated upon their decision, but instead showed a main effect of deliberation. Together, this implies that default nudges are not dependent on elaborate processing in order to be effective, but that deliberation can in parallel lead to different choice outcomes.