Spillover effects of reminder nudges in complex environments.

We present an experiment on the immediate and lasting effects of reminder nudges in a complex environment. In the study, 1,542 subjects face a setting where, within a brief time frame, they have to pay attention to and perform multiple actions in a computer game. The experiment investigates i) the effect of reminders on the reminded actions and their spillovers on nonreminded actions; ii) spillovers between multiple nudges when the number of reminded actions is increased; and iii) intertemporal spillovers from having been exposed to reminders on actions after reminders are withdrawn. Our findings reveal, first, that reminders have a positive effect on the overall number of actions performed. It results from the positive direct effect on the reminded actions dominating the negative spillovers on nonreminded actions. These negative effects are notable in our setting, where reminders could potentially have positive spillovers by freezing attention or by indirectly prompting actions similar to the reminded ones. Second, we observe that reminder nudges are scalable. Increasing the number of reminded actions leads subjects to take more actions overall, albeit with diminishing returns and more pronounced negative spillover effects. Third, after reminders are withdrawn, the positive effect on reminded actions diminishes, while negative spillovers on nonreminded actions persist, thus rendering reminders ineffective in increasing the overall number of actions performed.