In this case, definitely. A professor at New Mexico State University ran a little 'behavioral economics' experiment at a local supermarket.
He placed a strip of tape across the middle of the grocery carts, and added a sign reading, "place fruits and vegetables in front of this sign, and other groceries behind it."
This simple nudge doubled the amount of produce people bought -- ten times more than any nutrition education did. Why? Because it established new social norms. People felt that it was now expected behavior that they'd buy that much produce.
This kind of nudge is brilliant and confounding: it's remarkably effective, but it would never be discovered through surveys, interviews, or shop-alongs. How much do we know about how the brain works, how people work, how culture works?
The news story includes an interview with the NMSU professor who conducted the experiment.