Dog Poop Problem

Two kinds of signs for a rule: 

1. The sign board that says we shouldn't do it. 

2. The clues that everybody else is doing it. 

Which one would you follow? The second is Most important. 

Okay. So How we do we go from one situation where one thing we're trying to curb is the accepted norm?

First - there's never a good day to enforce (regulate) it. There's no smooth transition. There's has to be a quick transformation. So, announce a day that the change is going to occur. Have people subscribe to it, so they all have agreed to it. Then start using huge fines to start curbing it that day. 

source: https://class.coursera.org/behavioralecon-002/lecture/135