As I remember the broad strokes, college students – the guinea pigs of most psychology experiments – were divided into two sections.
Both groups were given monologues that they were to earnestly perform for an audience. One group was well compensated for their involvement; the other was not.
The content of the scripts was what sensible, civilized, average people would find distasteful, even abhorrent. As illustration, the Jewish people should have been exterminated in World War II, or slavery was actually positive for African Americans and should be reinstated.
Using a psychological evaluation prior to their performances, each actor was rated on a one-to-five scale as to how much their beliefs were in alignment what they were about to perform. Upon completion, they were again assessed as to their level of agreement. The purpose of these measurements was to understand if the students’ beliefs moved in the direction of what was espoused in their scripts after they performed them.