Following his initial experiment, Milgram conducted several additional experiments to examine factors that might increase or decrease obedience to authority. In one of these experiments, Milgram showed that participants were less likely to obey the experimenter’s orders if

Milgram showed that participants were less likely to obey the experimenter's orders if they were physically more proximate to the learner, and farther from the experimenter.

Explanation:

After conducting the initial experiment in the early 1960s at Yale University, Stanley Milgram (1933 - 1984) continued with its variations. As a result of the variation where he changed the proximity between the participants and the learners, he observed that participants' obedience was the lowest if a participant was holding the hand of a learner with 30% completion rate.

Moreover, if a participant received commands from the experimenter over the phone, obedience decreased to 21%.