Asking a person role-playing a guard in a prison simulation to be "firm" and "in the action" is mild compared to the pressure exerted by actual wardens and superior officers in real-life prison and military settings, where guards failing to participate fully can face disciplinary hearings, demotion, or dismissal. Although the research team asked all guards to be actively involved and firmly in control of the prisoners, it never instructed guards to employ brutality, and it explicitly banned the use of physical force.

Despite the request David Jaffee made, none of the guards behaved in a dominant way during the first two shifts. What made a difference was that on Day 2 the prisoners rebelled with verbal and physical confrontations challenging the full complement of nine guards. After the guards put down this rebellion, one of them declared that prisoners were "dangerous," and with that new view of the situation, several guards became much tougher in their actions.

It's important to note that in all my reports about the SPE, I have always highlighted individual differences among the guards. One or two guards on each shift became progressively meaner over time, others maintained a more even-tempered style, and a few were considered “good guards” from the prisoners’ perspectives. However, none of the “good guards” ever intervened to prevent the cruelty of their fellow guards. Even Blum acknowledges these individual differences among the guards. From my perspective, the range of guard behaviors undercuts any criticisms of the alleged demand characteristics that presumably distorted the results of the SPE. The fact that some guards remained "good guards" throughout the study shows that cruel guards chose to act on their own initiative. It is their extreme behaviors that generated the dramatic effects of the study, most notably those of the iconic guard nicknamed “John Wayne” for his macho performance.

3. One guard was intentionally play-acting his role. The prisoners nicknamed one guard on the night shift “John Wayne” because he acted like an out-of-control, Wild West cowboy. However, some critics have dismissed this guard's behavior as merely play-acting the role of tough guard. After the experiment, “John Wayne” (David Eshelman) explained that he modeled his role after the warden in the movie Cool Hand Luke. He said he wanted to be a realistic guard, so he stepped up to lead his night shift to be really tough on the prisoners. He did so by punishing prisoners repeatedly with extensive push-ups (occasionally, with some prisoners stepping on the back of others), limiting food access, or issuing arbitrary rules. With each passing night, he became more creatively evil in ways that went beyond being a tough guard. Indeed, he later said that he began to think of himself as a “puppeteer” who made prisoners do whatever he chose. In an extreme perversion of his experimentally assigned role, he devised an unthinkable way to humiliate all prisoners on the fifth night of the study. He ordered them to think of themselves as “camels,” half as males and the other half as females. Those ordered to be female camels had to bend over, while the male camel prisoners were ordered to hump them “doggy style,” which they reluctantly did by simulating sodomy. A video recording, made in my absence, indicated this episode lasted nearly ten minutes with all three guards shouting epithets and laughing hysterically. Fortunately, I had earlier decided to terminate the experiment the next morning.