In this article we show that it is possible to reduce carrier bags consumption without imposing additional costs on supermarket customers. To this end, we exploit the fact that people shopping in a certain area are likely to have homogeneous preferences on certain dimensions (e.g., sport teams). We implement a simple treatment in a supermarket in Naples, Italy: whenever a customer of the supermarket buys a single-use carrier bag we donate a small sum to an institution that is likely to be perceived negatively by the customers of the supermarket (an “anti-charity“). Vice versa, whenever a customer does not purchase a bag, we donate the same amount to an association that is likely to be perceived positively by the customers of the supermarket (a “charity”). We measure the impact of the treatment with respect to the previous weeks, the corresponding weeks of the previous year and we look at the persistence of the effect. Our results show that this treatment causes a significant reduction in bags consumption without imposing monetary costs on supermarket customers. Moreover, we show that our nudge can easily be used by regulators at virtually no cost by creating multi-city tournaments. We explain how these tournaments could be arranged.

在本文中，我们表明可以减少手提袋的消耗，而不会给超市客户带来额外的费用。为此，我们利用以下事实：在某个地区购物的人在某些方面（例如运动队）可能会具有相同的偏好。我们在意大利那不勒斯的一家超市中实施了一种简单的处理方法：每当超市的顾客购买一次性旅行袋时，我们都会向可能会受到超市顾客负面评价的机构捐赠一笔款项（“反慈善”）。反之亦然，每当顾客不购买行李时，我们便向一家超市顾客（“慈善机构”）可能会积极评价的协会捐赠相同数额。我们评估了治疗对前几周的影响，上一年的相应几周，我们将观察效果的持续性。我们的结果表明，这种处理方法可以显着减少袋子的使用量，而不会给超市客户带来金钱上的成本。此外，我们证明，通过创建多城市锦标赛，监管机构可以轻松地免费使用我们的微调服务。我们解释了如何安排这些比赛。