Editing Litter (section)

===Two-stage process model===
The two-stage process model of littering behavior describes the different ways in which people litter. The model was proposed by Chris Sibley and James Liu and differentiates between two types of littering: active and passive.<ref>Sibley, C.G., & Liu, J.H. (2003). Differentiating active and passive littering: A two-stage process model of littering behavior in public spaces. ''Environment and Behavior'', 35, 415–433.</ref>

The theory has implications for understanding the different types of litter reduction interventions that will most effectively reduce littering in a given environment. The theory states that, all things being equal, passive littering will be more resistant to change because of two psychological processes: 1. [[diffusion of responsibility]] that increases as the latency between when an individual places litter in the environment and when they vacate the territory, and 2. forgetting, which is also more likely to occur at longer delays between when an individual places litter in the environment and when they vacate the territory.