Advertising definitely works, I may not think about Coca Cola for weeks, and not ever drink it then see an advertisment somewhere, and then find myself drinking the stuff.
I'm wondering, if it would be possible to have a subject, and for a few hours, revolve everything around say the number 31. what are the chances, IF i a few hours later ask them for a number between 1 and 100 that they will pick the number 31.