So, im graduating with a Psychology degree this semesters, maybe I can put this in perspective.
Let me put this out there first, the Milgram experiment was a valuable experiment. Many many experiments today are actually based off of it.
Now to the meat, HOLY SHIT YES IT WAS UNETHICAL. Many people here are saying 'Oh, they could of stopped at any time, it was a psychological experiment, da da da da da." Its actually a study that made our ethics evolve. I dont know how yall think this would be anywhere near ethical, but it isnt. Funny enough, Milgram saw this and made his test different and more ethical to continue them.
First off, no, they couldn't stop at any time. The pressure put on from the experimenter made them continue. Psychological ethics state, if someone wants to quit and leave, you let them. This experiment showed that you can coerce people into staying, and that is unethical.
Second off, it could be psychologically harming. "Oh, they knew it was a scientific study, oh, it wont hurt them later on." These explanations dont do squat. Just because its a scientific study doesnt mean that we have free will to do anything we want to them, they look to us for -safety- during the experiment, both physically and psychologically. Onto the next point... It can easily affect someone later in life, since this is about -torturing- someone, and to top it all off, the recordings that were played first talked about 'heart' problems, then went silent even more the questions. Many people thought that they did major harm to this person,
http://www.youtube.com/watch?v=yr5cjyokVUs
Seriously guys, dont try to be arm chair psychologist and see this as ethical. Psychology has high ethics to protect our participants, and anything that could provide physical and psychological harm is heavily critique before, during, and after the experiment. Hell, my own experiment now uses deception and provokes a high sense of envy in a participant, so I need to put it on my consent letter, carefully watch the participant in the study, and debrief them after.