Association for Public Policy Analysis & Management

Cities across the country are adopting organics collection programs (OCPs) in order to curb the flow of food waste into landfills and prevent the resultant greenhouse gas emissions. While most cities focus on transforming the systems of provision (e.g., infrastructure and institutional aspects) in implementing OCPs, few engage the social aspects of food waste (Bulkeley & Askins, 2009). Indeed, despite easy-to-use curbside bins, much of what households place in landfill bins could be recycled or composted (SF Environment, 2013). This research develops evidence-based policy tools to help cities improve OCPs and reduce the environmental impact of cities.

The motivation for such programs in cities often hinges on the expected benefits of diversion improvements, yet there is reason to believe that as residents begin to separate food waste, cities may derive additional benefits as a result of "spillover behaviors." Spillover behaviors are additional changes that develop in "non-target behaviors" (Truelove et al., 2015). This research examines whether residents who begin separating food waste in a new curbside OCP also change other behaviors such as meal planning, and energy and water conservation behaviors that further reduce the environmental impact of cities.

Data are based on a longitudinal field experiment (n=364) which first tested a structural intervention (i.e., curbside OCP) and then a social intervention (i.e., norm communication) to improve food scrap separation. This work is the first to test social norms messaging in the context of curbside OCPs, building on previous research in energy and water domains (Osbaldiston & Schott, 2012). Ultimately, while curbside bins increased composting among residents generally, those receiving normative messages about neighborhood participation significantly increased composting, retention, and policy support.

Further, to examine the unintended consequences of the intervention, the authors used mediation modeling (OLS regression) to determine whether participants who began separating food waste (i.e., target behavior) are more likely to adopt pro-environmental spillover behaviors. This work is the first to longitudinally examine spillover behaviors resulting from newly adopted target behaviors, and the first to evaluate new causal mechanisms for this process. Results indicate that beginning to separate food waste led to increased thoughts about food waste in participants' daily lives, which mediated the adoption of spillover behaviors including food planning as well as water and energy conservation behaviors. Thus, the data support cognitive accessibility as a novel and robust pathway for spillover.

This research not only advances social-psychological literature on behavior change and spillover behaviors, but also identifies additional benefits for cities weighing the costs and benefits of implementing such programs. The results highlights the need for greater understanding of the interrelations of household behaviors and material flows in the household to achieve broader environmental policy goals.