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.

Economic theory suggests that energy subsidies can lead to excessive consumption and environmental degradation. However, the precise impact of energy subsidies is not well understood. We analyze a large energy subsidy: the California Alternate Rates for Energy (CARE). CARE provides a price reduction for low-income consumers of natural gas and electricity. Using a natural field experiment, we estimate the price elasticity of demand for natural gas to be about −0.35 for CARE customers. An economic model of this subsidy yields three results. First, the natural gas subsidy appears to reduce welfare. Second, the economic impact of various policies, such as cap-and-trade, depends on whether prices for various customers move closer to the marginal social cost. Third, benefits to CARE customers need to increase by 6 percent to offset the costs of the program.

Public recognition is frequently used to motivate desirable behavior, yet its welfare effects—such as costs of shame or gains from pride— are rarely measured. We develop a portable empirical methodology for measuring and monetizing social image utility, and we deploy it in experiments on exercise and charitable behavior. In all experiments, public recognition motivates desirable behavior but creates highly unequal image payoffs. High-performing individuals enjoy significant utility gains, while low-performing individuals incur significant utility losses. We estimate structural models of social signaling, and we use the models to explore the social efficiency of public recognition policies.