Normative Social Influence
Sometimes people behave in ways just to gain approval from others, even if they don't necessarily believe in what they are doing. This is normative social influence -- influence resulting in the desire to gain approval or avoid disapproval. For example, if you go to a play, many times you will applaud when others do even if you didn't really like the play that much. You do this to avoid the diapproval of the other people.