By 1980 nearly half of incoming psychology students knew Milgram’s experiment

Evidence

I did not try to run a laboratory aggression study again until 1983. In the meanwhile, I discovered in 1981 that 48% of a sample of introductory psychology students at my university said they knew about Milgram’s experiment by the time they matriculated. So in 1983 I attempted to disguise the experiment as a game of Battleship in which subjects could give blasts of noise to (supposed) opponents to confuse them. But nearly half the students wrote on a post-experimental questionnaire that the real purpose of the study was to see how aggressive they would be. — Bob Altemeyer, The Authoritarian Specter, 3910