Milgram's variations lack internal validity - situational factor A03
P: Milgram's OG experiment criticised for lacking internal validity, his variations even more criticised.
E: Orne & Holland argued ppt knew procedure faked = could been because of extra experimental manipulations.
E: E.G. , in variation where experimenter replaced by member of public, even Milgram recognised situation so contrived that some ppt may worked out truth.
L: This limitation as its unclear whether results are genuinely due to obedience or due to ppt seeing through deception and acting accordingly 'play acted'.