Social-norm messaging and management of environmental cues

Mechanism

Littering is strongly cued by context. People litter more in already-littered places and when they see others litter (a descriptive norm that "this is what people do here"), and less in conspicuously clean spaces. Messaging works best when it pairs a descriptive norm ("most people dispose of their litter properly") with an injunctive norm ("littering here is not acceptable"); combined, they reinforce each other and avoid the boomerang effect a descriptive norm alone can trigger. Related cues — even printed "watching eyes" above a message — measurably increase compliance.

Where it fits

A cross-cutting, low-cost lever applicable to any setting, and a natural complement to keeping hotspots clean — rapid removal both fixes the harm and resets the norm.

Operating profile and limits

Effects are real but modest and context-dependent; the strongest, most replicable finding is simply that clean environments stay cleaner, so keeping a space spotless is itself an intervention. Field evidence comes largely from controlled experiments, and durability at municipal scale is less well established.