teilo is right: this really has nothing to do with the act of praying, but rather people's brain reactions to those whom they intrinsically believe to be in a position of authority/power. Related to your question, I remember reading a few articles about this in the past. Essentially, brains deep in prayer == brains deep in meditation. (Quick search - this might be one of those articles: http://www.time.com/time/magazine/article/0,9171,995465-6,00...)