From the viewpoint of this being and objective experiment, I would be a little bit worried about everyone knowing the nature of the experiment you had in mind, because, as you probably know, in industrial studies there's a well-known effect, I think it's called the Hawthorn effect, which merely by studying a group of people you change their behaviour and their output, simply because they know that you're taking an interest in them and they've got some idea of your expectations.