Which nudge works best? Testing Interventions for recyclable waste across residential types

This research applies a well-known behavioral economic concept, the nudge theory, to promote waste segregation behavior. The study has three main objectives. First, it investigates whether nudge-based interventions enhance waste segregation behavior. Second, it identifies the most effective intervention and, third, assesses its impact across different residential types. A 32-week field experiment was conducted across 12 residential sites, covering detached houses, townhouses, and condominiums in the east of Bangkok Metropolitan area. All sites participated in a 16-week baseline phase followed by a 16-week intervention phase and were randomly assigned to one of four groups: information framing, physical adaptation, social norms and feedback, or control. Results show that all three interventions improved recycling behavior, with physical adaptation yielding the largest increase in recyclable waste weight (+82.13%), followed by social norms and feedback (+74.41%) and information framing (+49.60%). When examined by residential type, condominiums exhibited the highest overall responsiveness (+101.94%), followed by townhouses (+57.15%), while detached houses showed a decline. This study provides valuable insights into the effectiveness of nudge theory in promoting waste segregation behavior and highlights the need for tailored strategies based on residential contexts to maximize intervention success. • This study applies nudge theory in a 32-week field experiment across 12 residential sites, testing three behavioral interventions—information framing, physical adaptation, and social norms and feedback—to improve waste segregation. • Among the interventions, modifying the physical environment, such as improving bin accessibility and visibility, resulted in the highest increase in recyclable waste weight by 82.13%, outperforming social norms and feedback at 74.41% and information framing at 49.60%. • Residential context significantly influenced intervention effectiveness, with condominiums showing the highest responsiveness at a 101.94% increase in recyclable waste weight, followed by townhouses at 57.15%, while detached houses exhibited minimal behavioral change. • Physical adaptation had the most persistent effect on waste segregation over time, whereas social norms and information framing interventions showed a decline in effectiveness, highlighting the importance of durable intervention strategies. • The findings emphasize the cost-effectiveness of structural modifications, such as better bin placement, over message-based interventions and provide actionable insights for urban waste management policies and sustainable recycling programs.