Setting new behavioural standards : sustainabilty pledges and how conformity impacts their outreach

Sustainability pledges are en vogue. In the business sector, but also in climate negotiations, pledges are used to signal actors' intention to act pro-environmentally. Laboratory experiments testify to the potential effectiveness of these public declarations. Previous work has examined under which conditions subsequent trust and cooperation can flourish. In this study, I postulate that also conformity is an important determinant for the effectiveness of pledges. In specific, I examine what role social influence plays in the decision to pledge. In a public good game, subjects can make prior play a pledge to contribute to the public good in the socially optimal way. Across treatment conditions, I vary the way in which the pledges are elicited. Hence, the degree of social influence on pledge making is manipulated and its impact can be examined. I find that when individuals are aware that the majority of other subjects decided to pledge, they are likely to conform and also make the pledge. The emergence of such a critical mass can be stimulated when the elicitation of pledges is based on previous contribution behavior. Overall, this commitment nudge is effective. Both socially-oriented and previously not socially-oriented subjects modify their behavior after the pledge.