What were the ethical concerns involved in the Stanford Prison Experiment, Asch’s Conformity Experiment, and Milgram’s Shock-Obedience Experiment?

What were the ethical concerns involved in the Stanford Prison Experiment, Asch’s Conformity Experiment, and Milgram’s Shock-Obedience Experiment? Should researchers be able to use deception for the sake of their experiments? Write 1 to 2 pages describing why or why not?