Generalisability
Volunteers are likely to be particularly obedient (after all, they want to be doing the experiment). Generalisability. On the other hand, volunteers tend to listen to instructions and take the procedure seriously, which is representative of people in real life situations of power being misused.
A sample of 40 is quite large, but anomalies (unusually cruel, gullible or timid people) might spoil the results. The original sample was all-male, which cannot generalise to women, and all-American, which may not generalise to other cultures. It may also be “time-locked” in the early 1960s with its rather deferential culture.
When you put all of Milgram’s variations together, he tested 780 people, which should remove anomalies. However, some of the Variations (like #13) only tested 20 participants, so a few rebellious individuals (like the ones who overpowered the confederate) might spoil things.
Variation #8 tested women, with the same obedience level (65%) as men. This lends support to the idea that the original sample was representative.
Reliability
Milgram’s procedure is very reliable because it can be replicated – between 1961-2 he carried out 19 Variations of his baseline study. Burger followed Milgram’s script wherever possible, indicating high reliability. Milgram also filmed parts of his study, allowing viewers to review his findings (inter-rater reliability).
Features that make for standardised procedure in this study include the pre-scripted “prods” used by the Experimenter, the tape-recorded responses from Mr Wallace, the fact that the Teacher cannot see Mr Wallace.
A serious criticism is levelled by Gina Perry (2012), that Milgram did not follow standardised procedures. John Williams (the Experimenter) admitted to Perry that Milgram was only strict about the pre-scripted “prods” in the first study and afterwards Williams was free to improvise. This made obedience in the Variations seem higher than it really was.
Application
The study demonstrates how obedience to authority works and this can be used to increase obedience in settings like schools, workplaces and prisons. Authority figures should wear symbols of authority (uniforms) and justify their authority with reference to a “greater good”.
Milgram (1974) links his findings to the actions of the Nazi’s following the orders by Hitler.
Validity
lacks ecological validity because the task is artificial – in real life, teachers are not asked to deliver electric shocks to learners. However, Milgram’s reply is that events like the Holocaust were just as unusual and strange and that people in these situations felt similarly to his participants: they had been dropped into an unfamiliar situation and didn’t know how to respond.
Some critics claim that the participants were play-acting: they knew (or suspected) that the set-up wasn’t real. However, their visible distress (filmed by Milgram) counts against this.
However Perry challenges the validity (and generalisability and reliability) of Milgram's procedures - Milgram’s data is not to be trusted. She alleges that, as an ambitious young scholar, Milgram twisted the data to make it look as if there was “a Nazi inside all of us” to make himself famous. In Variation #8 in particular, Mr Williams (the Experimenter) would not let the women back out of the study even after using 4 prods. Supposedly, Milgram encouraged this because it was important for his theory that men and women should both experience the Agentic State (otherwise it looks like male obedience isn't really obedience at all - it's just aggression). Perry also alleges, after studying unpublished letters at Milgram's old department at Yale, that several participants did suspect the study was a trick. Some of them wrote to MIlgram and pointed out that Mr Wallace's cries of pain seemed to come from the speakers, not the room next door
Ethics
The main criticism is that participants’ wellbeing was ignored: they were deceived (about the shocks) and did not give informed consent (they were told it was a memory test, not an obedience test). When they tried to withdraw, the “prods” made this difficult for them. This makes it harder to recruit for future research.
The main defence is that the study would not have been possible if participants knew what was being investigated. After all, everyone who had the study described to them beforehand felt sure that they would disobey.
Milgram argues that, after the Holocaust, a scientific understanding of obedience is so importance it justifies this sort of research. He also downplayed the seriousness of the distress, claiming his participants experience “excitement” similar to watching a scary movie, not lasting trauma.
Milgram also extensively debriefed his participants and went to lengths to show that no lasting harm had befallen them.