Social norms are strongly associated with pro-environmental behaviors, but the evolution and dynamic effects of norms are less well understood. This article builds on the distinction of norms being descriptive, characterizing what people actually do, or injunctive, characterizing what people should do. It identifies four categories of norms with the further distinction of whether the norms arise from the personal beliefs and actions or from the behaviors and judgments of others. The analysis uses five years of longitudinal US data that track household recycling and controls for household characteristics as well as differences in state recycling laws. The results extend previous research by showing that personal norms exhibit cascading dynamics in which norms encourage later changes in recycling, while recycling encourages later changes in personal norms. This mutual reinforcement implies that societal actions encouraging change in either personal norms or recycling will support growth in the other. Recognizing this interdependence can assist in the effective utilization of social norms as a behavioral policy instrument.

We report two studies investigating whether, and if so how, different low-cost interventions affect voter registration rates. Low-cost message-based interventions are increasingly used to promote target behaviours. While growing evidence shows that such ‘nudges’ often significantly impact behaviour, understanding of why interventions work or fail in particular contexts remains underdeveloped. In a natural field experiment conducted before the 2015 UK general election, we varied messages on a postcard sent by Oxford City Council to unregistered students encouraging them to join the electoral register. Our primary finding from the field study is that just one of our interventions – a reminder that people failing to register may be fined – has a significant positive impact. Offering small monetary rewards to register instead has a negative but insignificant effect. In a second study, using an online experiment we identify a particular mechanism explaining the influence of this intervention. Specifically, we show that our interventions have divergent effects on perceptions of the normative appropriateness of registering: emphasising that failing to register is punishable by law strengthened the perception that one ought to register, while offering monetary inducements for registering weakened the perception that doing so is an action already expected within society.

The success of choice architecture, including its adoption in government policy and practice, has prompted questions of whether choice architecture design decisions are sufficiently transparent and publicly acceptable. We examined whether disclosing to decision-makers that a particular choice architecture is in place reduces its effectiveness and whether an understanding of the effectiveness of choice architecture design decisions increases their acceptability. We find that disclosure of the design decision does not reduce its effectiveness and that individuals perceive the effectiveness of specific designs to be higher for others than for themselves. Perceived effectiveness for self increases when individuals have actually experienced the effect of a design decision rather than having it simply described to them. Perceived effectiveness for oneself and others increases the acceptability of the designs. We also find that the intentions of the source matter more than who the source actually is. Important for policy-makers, then, is that disclosure of design decisions does not reduce their effectiveness, and their acceptability depends on their perceived effectiveness and the inferred motivations of the design architect.

We argue that the diverse components of a choice architecture can be classified into two main dimensions – Message and Environment – and that the distinction between them is useful in order to better understand how nudges work. In the first part of this paper, we define what we mean by nudge, explain what Message and Environment are, argue that the distinction between them is conceptually robust and show that it is also orthogonal to other distinctions advanced in the nudge literature. In the second part, we review some common types of nudges and show they target either Message or Environment or both dimensions of the choice architecture. We then apply the Message–Environment framework to discuss some features of Amazon's website and, finally, we indicate how the proposed framework could help a choice architect to design a new choice architecture.

Thaler and Sunstein advocate ‘libertarian paternalism’. A libertarian paternalist changes the conditions under which people act so that their cognitive biases lead them to choose what is best for themselves. Although libertarian paternalism manipulates people, Thaler and Sunstein say that it respects their autonomy by preserving the possibility of choice. Conly argues that libertarian paternalism does not go far enough, since there is no compelling reason why we should allow people the opportunity to choose to bring disaster upon themselves if sometimes they will make the wrong decision. She defends ‘coercive paternalism’. The present paper argues that errors in reasoning are not due only to cognitive biases. People also make errors because they have an insufficient level of general intelligence. Intelligence is distributed on a continuum. Those who fall on higher levels of the continuum have greater abilities, in certain contexts, to reason about both their own and others’ interests. Coercive paternalism may sometimes be appropriate to prevent less intelligent people from engaging in self-destructive behavior due to errors of reasoning.

Nudging is considered a promising approach for behavioural change. At the same time, nudging has raised ethical concerns, specifically in relation to the impact of nudges on autonomous choice. A complexity is that in this debate authors may appeal to different understandings or dimensions of autonomy. Clarifying the different conceptualisations of autonomy in ethical debates around nudging would help to advance our understanding of the ethics of nudging. A literature review of these considerations was conducted in order to identify and differentiate between the conceptualisations of autonomy. In 33 articles on the ethics of nudging, we identified 280 autonomy considerations, which we labelled with 790 unique autonomy codes and grouped under 61 unique super-codes. Finally, we formulated three general conceptualisations of autonomy. Freedom of choice refers to the availability of options and the environment in which individuals have to make choices. Agency involves an individual's capacity to deliberate and determine what to choose. Self-constitution relates to someone's identity and self-chosen goals. In the debate about the ethics of nudging, authors refer to different senses of autonomy. Clarifying these conceptualisations contributes to a better understanding of how nudges can undermine or, on the other hand, strengthen autonomy.