Costly signaling theory provides an explanation for why humans are willing to a pay a premium for conspicuous products such as luxury brand-labeled clothing or conspicuous environmentally friendly cars. According to the theory, the extra cost of such products is a signal of social status and wealth and leads to advantages in social interactions for the signaler. A previous study found positive evidence for the case of luxury brand labels. However, an issue of this study was that some of the experiments were not conducted in a perfectly double-blind manner. I resolved this by replicating variations of the original design in a double-blind procedure. Additionally, besides the luxury label condition, I introduced a “green” label condition. Thus, the hypothesis that signaling theory is able to explain pro-environmental behavior was tested for the first time in a natural field setting. Further, I conducted experiments in both average and below-average socioeconomic neighborhoods, where, according to signaling theory, the effects of luxury signals should be even stronger. In contrast to the original study, I did not find positive effects of the luxury brand label in any of the five experiments. Nor did I find evidence for a green-signaling effect. Moreover, in poor neighborhoods a negative tendency of the luxury label actually became evident. This suggests that a signaling theory explanation of costly labels must take into account the characteristics of the observers, e.g. their social status.

Numerous laboratory experiments have established peer-sanctioning as an important driver of norm compliance and cooperation in human groups. However, systematic evidence of peer-sanctioning occurring in the field is still rare. Here we present results from a quasi-experimental field study investigating the enforcement of the silence norm in the train. We let a confederate play music on his/her mobile phone in an open-plan train car and measure the time until a negative sanction occurs (if any). The silence norm is enforced in 45 of 90 cases, enforcement rates do not differ across silent- and non-silent-area cars, and the more passengers are in a car, the more likely is the silence norm enforced. Passengers’ propensities to enforce the silence norm are in line with predictions derived from the asymmetric volunteer’s dilemma (VOD). The higher a passenger’s net benefit from enforcing the silence norm is, the more likely is the passenger to negatively sanction the norm breaker. Our findings extend the validity of results from laboratory experiments which conceive the second-order free-rider problem as a VOD.

Rapid and comprehensive social change is required to mitigate pressing environmental issues such as climate change. Social tipping interventions have been proposed as a policy tool for creating this kind of change. Social tipping means that a small minority committed to a target behaviour can create a self-reinforcing dynamic, which establishes the target behaviour as a social norm. The possibility of achieving the large-scale diffusion of pro-environmental norms and related behaviours with an intervention delimited in size and time is tempting. Yet, the canonical model of tipping, the coordination game, may evoke overly optimistic expectations regarding the potential of tipping, due to the underlying assumption of homogenous preferences. Relaxing this assumption, we devise a threshold model of tipping pro-environmental norm diffusion. The model suggests that depending on the distribution of social preferences in a population, and the individual cost of adopting a given pro-environmental behaviour, the same intervention can activate tipping, have little effect, or produce a backlash. Favourable to tip pro-environmental norms are widespread advantageous inequity aversion and low adoption costs. Adverse are widespread self-regarding preferences or disadvantageous inequity aversion, and high costs. We discuss the policy implications of these findings and suggest suitable intervention strategies for different contexts.