I admit I don’t pick up every piece of litter I see. It’s simply not possible—I would never make it to work in time, or home, again! But as a result I do see social norms in action. Take this scene at the Swindon train station. I pass through here on my way to the office every day, and noticed the Costa cup appear on the railing a few days ago. This afternoon it was joined by a friend from McDonald’s. This underscores why regular cleaning—not just the occasional pick up—is so important in breaking the cycle. Of course, stopping litter in the first place is even better!