Final answer:
The Milgram and Zimbardo studies are considered unethical because they violated the principles of informed consent and caused psychological harm to participants.
Step-by-step explanation:
The Milgram and Zimbardo studies are considered unethical because they violated the principles of informed consent and caused psychological harm to participants. In the Milgram Experiment, participants were told to administer increasingly intense electric shocks to others, which caused extreme emotional distress to the participants. Similarly, in the Stanford prison experiment conducted by Zimbardo, participants were subjected to psychological harm as they took on the roles of prisoners and guards.