The four prompts 

The man in the grey technician's coat was not an actor playing a tyrant. He was played by a local high school biology teacher, instructed to be firm, impassive and unemotional, and his verbal repertoire when a participant hesitated consisted of four prods delivered in sequence.

Prod one: Please continue, or Please go on. Prod two: The experiment requires that you continue. Prod three: It is absolutely essential that you continue. Prod four: You have no other choice, you must go on. If a participant asked whether the learner might be injured, there was a special reassurance about the shocks being painful but not dangerous. If he objected that the learner did not want to go on, the answer was that whether he likes it or not, the teaching must continue.

It is worth noticing what is absent. There is no threat of losing the fee, no suggestion of any penalty, no shouting, no appeal to patriotism or ideology. The participants were free to leave, had already been paid, and knew it. All the experimenter offered was the assertion that the procedure had to be completed, backed by the setting of a university laboratory and by his own apparent responsibility for the outcome. That thinness is the finding. Compliance in this room did not require power in any coercive sense. It required only someone who appeared entitled to define the situation.

There is also a documented limit to how tidy the script was in practice. Researchers working with the Milgram papers at Yale, notably Gina Perry, have pointed out that recordings show the experimenter departing from the four prods in some sessions, improvising further pressure, repeating himself, and pushing reluctant participants well beyond the standardised procedure. That is a genuine methodological criticism. It means the pressure applied was not perfectly uniform across participants, and it weakens any attempt to treat the obedience percentage as a precise constant. It does not remove the core observation, which held across dozens of separately run conditions with different experimenters and settings.

Read carefully, the criticism sharpens the lesson rather than dissolving it. If a persistent voice claiming institutional authority produces compliance, and if that voice tends to escalate when resisted, then the mechanism is a social relationship rather than a stimulus. The fourth prod is the interesting one for that reason. You have no other choice is straightforwardly false, and it was persuasive anyway.

Change the room instead of the words, however, and the numbers move much further than most people expect.