ethical - milgram

• deception - necessary for internal validity. if pts knew true aim there would be demand characteristics and results would lack validity
• right to withdraw - told they could leave at start of study and the fact 1/3 left is proof of this
• protection from psychological harm - psychiatrist interviewed pts a year later and there was no evidence of emotional harm. most were glad they took part because they learnt how to resist social influence
• value of research - 'opened our eyes' that we are all possible capable of being like the pts in the study.