The authors thank Kathy Nguyen for her support in conducting this experiment and for her assistance in creating the treatment messages and ensuring the experimental design was policy relevant. The authors also thank Herb Richardson for transferring the outcome data, Merlin Hanauer and Juan Jose Miranda for work to compile the data. John List, Subrendu Pattanayak, Laura Taylor, and participants at the 2009 AEA-ASSA meetings and seminars at the Georgia Water Wise Council, the Georgia Association

Abstract We formalize a research design to uncover the mechanisms underlying long-term reductions in energy consumption caused by a widely implemented nudge. We consider two channels: technology adoption and habit formation. Using data from 38 natural field experiments, we isolate the role of technology adoption by comparing treatment and control homes after the initial resident moves, which discontinues the treatment for a home. We find that fully half of energy reductions persist in the home after treatment ends and show this persistence is consonant with a technology adoption channel. The role of technology in creating persistent behaviour change has important implications for designing behavioural interventions and evaluating their long-term social impacts.

Policymakers increasingly use norm-based messages to promote conservation efforts. Despite the apparent success of such strategies, empirical analyses have thus far focused exclusively on short-run effects. From a policy perspective, however, whether and how such strategies influence behavior in the long-run is of equal interest. We partner with a metropolitan water utility to implement a natural field experiment examining the effect of such messages on longer-run patterns of water use. Empirical results are striking. While appeals to pro-social preferences affect short-run patterns of water use, only messages augmented with social comparisons have a lasting impact on water demand.

This study examines why people initially give to charities, why they remain committed to the cause, and what factors attenuate these influences. Using an experimental design that links donations across distinct treatments separated in time, we present several results. For example, previous donors are more likely to give, and contribute more, than other donor types. Yet, how previous donors were acquired is critical: agents initially attracted by an economic mechanism are more likely to continue giving than agents attracted by a nonmechanism factor. From a methodological viewpoint, our study showcases the benefit of moving beyond an experimental design that focuses on short-run substitution effects. (JEL C93, D64, D82, H41, L31, Z12)