Do professions seem to help people perform better compared to areas that don’t have a professional oath or certification?

I would like to think so. It's hard to figure out, exactly. But I can tell you, for example, engineers have told me that they feel that wearing the engineering ring on the left hand is actually very helpful, because when they draw something and they see the ring; it reminds them about the mission of engineering.

Doctors' white coats are interesting, because on the one hand, they are a reminder about what the doctor should be standing for, but in England they just banned them, because doctors don't wash them the same way they would wash their clothes, so they are a means for transmitting infection. But in general, reminders are useful.

We did an experiment with a big insurance company. We mailed 20,000 forms that asked people how many miles they drove last year. People received one of two forms. You were either asked to put in the number of miles you drove and then sign below. Or you were asked to sign at the top and then write the number of miles below that.

Everybody wants to report a lower mileage, but our logic was that if we remind people about their own morality, they would actually report the higher mileage. And that's what we got. On average, people reported driving 2,700 miles more if they first signed and then wrote the number down.

Now this is not exactly professionalism, but it says that it makes a significant difference when you remind people about their core values.

From an interview with Dan Ariely entitled does cheating matter