This paper investigates differences between a default, a recommendation, and a mandatory minimum contribution on private provision of a large scale public good (climate protection). Information on the regulator (neutral experimenter, expert or politician), its interaction with the intervention type, as well as with pre-intervention intrinsic motivation on voluntary contributions is analyzed. Data are from an online framed field experiment with a sample representative of the German internet using population. Main insights are: neither a recommendation nor a default close to the pre-intervention average change contributions; identifying the regulator reduces contributions when accompanying the recommendation, but not the default; contributions above the pre-intervention average are reduced by the default but increased by the mandatory minimum relative to the control; only the default negatively interacts with high intrinsic motivation; and regulator attributes neither interact with intrinsic motivation, nor with the type of intervention. The study contributes to the discussion of nudges as public policy instruments by comparing them to alternative interventions, i.e. pointing at or pushing contributions, and by shedding light on making the source of the intervention transparent.

Nudges receive growing attention as an effective concept to alter people’s decisions without significantly changing economic incentives or limiting options. However, being often very subtle and covert, nudges are also criticized as unethical. By not being transparent about the intention to influence individual choice they might be perceived as limiting freedom of autonomous actions and decisions. So far, empirical research on this issue is scarce. In this study, we investigate whether nudges can be made transparent without limiting their effectiveness. For this purpose we conduct a laboratory experiment where we nudge contributions to carbon emission reduction by introducing a default value. We test how different types of transparency (i.e. knowledge of the potential influence of the default, its purpose, or both) influence the effect of the default. Our findings demonstrate that the default increases contributions, and information on the potential influence, its purpose, or both combined do not significantly influence the default effect. Furthermore, we do not find evidence that psychological reactance interacts with the influence of transparency. Findings support the policy-relevant claim that nudges (in the form of defaults) can be transparent and yet effective.

Labeling news as fake is a recent phenomenon occurring predominantly online, and increasingly in political online environments. This paper investigates the influence of expressed doubt in media independence on trust in news reports on climate change, and on trust in more scientific sources. Evidence from a laboratory experiment does not suggest that reading a media-critic statement affects perceived trust in the media-, or the scientific source reporting on climate change. Bayesian analyses provide a practical interpretation of the null findings, and further analyses show that the statement decreases trust in the scientific source when subjects read the media article first. Findings add to the emerging literature on fake news, echo chambers and filter bubbles, suggesting that labeling stories or outlets as fake news may not affect public opinions. Further research is needed to substantiate this conclusion.