Anti-litter procedures in an urban high-density area.

Researchers paid neighborhood kids to pick up trash. Each child got a set yard to keep clean. They tried two pay rules: one for cleaning the whole yard, one for the weight of trash.

The study ran in a crowded city block. No clinic, no lab—just sidewalks and stoops.

Money for a clean yard worked. Trash on the ground dropped fast.

Money for pounds of trash barely helped. Kids collected more, but the block stayed messy.

Szempruch et al. (1993) got adults to recycle more by posting clear signs above office bins. Both studies aim for cleaner streets, but one uses pay and the other uses prompts.

Clayton et al. (2006) used a polite sign to boost seat-belt use at a parking-lot exit. Like Catania et al. (1974), they showed cheap cues can steer public behavior—no staff needed.

Rutter et al. (1987) paired tokens with practice to teach kids to buckle up. They built on the same pay idea, then added rehearsal and praise. The token part stayed; the target skill moved from litter to safety.

If you want a cleaner playground, pay for the zone, not the weight. Assign each child a patch, hand over the tokens when it looks tidy. Skip scales and bag counts—they reward collecting junk, not leaving a clean space.