What the results revealed is that when the teacher could see and hear the student, they couldn't go very far before they completely quit the experiment; when they could hear them, but not see them, they could go further but still not very far before they quit; when they could see them, but not hear them, they could go further but still not very far; but when they could neither see nor hear the impact of their decisions, 65% of those "teachers" were able to go all the way and kill the guy.