A psychological experiment is a scientific study designed to understand how people think, feel, and behave. Researchers manipulate one or more variables to observe the effects on participants' responses. This method helps psychologists test theories and gain insights into human behavior. These experiments often involve control and experimental groups, where the latter receives a specific treatment or intervention. Famous examples include the Stanford prison experiment and Milgram's obedience study, which revealed important aspects of social behavior and authority. Ethical guidelines are crucial to ensure the well-being of participants during these studies.