In the Stanford Prison Experiment, Philip Zimbardo had two main roles: he was both the principal investigator (PI) of the study and the superintendent of the "prison." As the PI, Zimbardo designed the study, oversaw the data collection and analysis, and interpreted the results. As the superintendent of the "prison," Zimbardo was in charge of the day-to-day operations of the experiment and was responsible for the well-being of the participants.
Having these two roles could have caused a conflict of interest in the study. As the superintendent of the "prison," Zimbardo had a vested interest in maintaining the integrity of the experiment and ensuring that the study proceeded as planned. However, as the PI, Zimbardo had a scientific responsibility to remain objective and to report the results of the study, even if they were not in line with his expectations.
Furthermore, because Zimbardo was so closely involved in the day-to-day operations of the study, he may have been more likely to overlook potential ethical issues or to dismiss concerns raised by participants or outside observers. This could have contributed to the ethical violations that occurred during the study, such as the mistreatment of the participants and the lack of informed consent.
Overall, the dual role that Zimbardo played in the Stanford Prison Experiment could have compromised the validity and reliability of the study, as well as the ethical treatment of the participants.