Reinforcement and rate of litter depositing.

Quilitch et al. (1973) tested if simple rewards could get people to pick up trash in a public park.

They ran an ABAB reversal design. When littering dropped, they removed the reward. When it rose again, they brought the reward back.

The study did not list ages or diagnoses. It focused on the setting, not the people.

Trash in the park went down every time the reward was in place.

The area also looked cleaner to the eye. When the reward stopped, litter returned.

Clark et al. (1972) did the same thing one year earlier in a forest campground. They let kids choose their own prizes. Litter dropped fast. Quilitch et al. (1973) shows the idea works again in a new place.

Burgess et al. (1971) used tokens in two movie theaters and hit over 90% clean-up. Quilitch et al. (1973) used a simpler reward and still got the same upward swing.

Hayes et al. (1975) came next and added a twist: staff marked trash ahead of time and paid for each piece. Their 55–88% drop shows the tactic can be scaled with less staff time.

You can cut litter anywhere by handing out small, sure rewards. No speeches, signs, or extra trash cans needed. Try a token, a point, or a treat right after the person tosses trash. Take data for one week, remove the reward, and watch the litter return. Put the reward back and see the clean-up rise again. This quick reversal proves the reward is doing the work.