This can be compared to mob mentality, how within a large group of people, an individual may completely change their normal methods of behavior. These guards may have been kind good hearted men, however when placed into this prison environment they all began acting cruelly. Mob mentality may effect anyone although you may previously deny falling into such behaviors. If these volunteers had been told what they would act like during the experiment, they most likely would not believe it. Most people would not accept the fact that they could easily change their morality through such influence, however the psychological effect of the given surroundings of a prison is undeniably vile and crude, and thus you begin to assimilate to such standards.