The use of stimulus control over littering in a natural setting.

Researchers wanted more fans to toss trash into big gray drums at four football games. They glued a bright plywood "har" shape on one drum and left the others plain. They weighed and counted litter after each game to see if the har helped.

No staff gave reminders. No prizes were handed out. The har was the only change.

The har drum collected more than twice as much trash by weight and by count. The plain drums stayed the same. The effect showed up every game.

Munce et al. (2010) got the same jump in recycling when they moved bins into classrooms instead of hallways. Both studies show one cheap visual tweak can double disposal without extra staff.

Fritz et al. (2017) used the opposite move: they took trash cans away so recycling was easier. Trash rose at first, then settled while recycling stayed high. W et al. added a cue; Fritz raised effort. Together they tell us you can push disposal either way.

Dunlap et al. (1991) cut illegal parking with bright reminder cards on windshields. Like the har, a simple community sign changed behavior fast.

You can double clean-up with a 30-minute craft project. Pick a bright, odd shape that sticks out from the setting. Zip-tie or tape it to your bin at the next clinic picnic, school fair, or staff lounge. No speeches, no tokens, no data sheets needed. Just watch the trash land where you want it.