Pro-environmental spillover under environmental appeals and monetary incentives: Evidence from an intervention study on household waste separation

This intervention study examined (1) the influence of household waste separation on other pro-environmental behaviors (behavioral spillover), (2) possible psychological mechanisms involved in such spillover, and (3) if the two waste separation interventions (environmental appeals vs. monetary incentives) differed in shaping spillover. Results showed that both strategies increased waste sorting behavior, which positively spilled over to other pro-environmental behaviors. However, no evidence was found for the hypothesized spillover mechanisms of pro-environmental identity, environmental concern, and relief of guilt, and the two external treatments did not significantly differ in their moderating effects on spillover. In addition to spillover, a positive pathway through changes in environmental concern was found for the environmental framing, while a negative pathway through changes in pro-environmental identity was found for monetary incentives. Overall, the findings indicate both behavioral spillover and other pathways to be responsible for the effects of two waste separation strategies on non-target environmental behaviors.