River Thames flows through London. People come to the London Bridge to see the Tower Bridge which allows ocean-going ships to pass beneath it.

Many visitors stopped in front of a pink public litter bin momentarily and threw litter away before crossing the bridge.

We knew adding human faces or adding controversial messages nudge our prosocial behaviors. Adding votes could be another effective intervention. I believe behavioral economics can play a critical role when public items are designed. Asking people to vote by splitting a litter bin into two sub bins looks more effective than designing a gigantic litter bin like a disposable coffee cup.