In 1971, professor Philip Zimbardo put together one of the most intriguing and famous psychology experiments ever: the Stanford Prison Experiment, designed to study the effects of incarceration on prisoners and guards. Using an advertisement to recruit college-aged men in the area for a one-of-a-kind study, Zimbardo and his team hoped to remove volunteers predisposed to mental illness and those with existing records from their experiment. Nonetheless, the Stanford Prison Experiment brought out those qualities in its participants.