Feminist attitude changes were measured against randomized control and experimental groups

Evidence

Six weeks later I recruited 160 students from these classes, who signed up by their secret numbers, for an experiment being run at 11:30, 12:30, and 1:30 on November 16. Participants in the first two sessions (N = 117) simply answered a booklet of surveys for me under the usual (control) “test-retest reliability” instructions. This booklet ended with the eight “Fembo” items. The 43 students who attended at 1:30, however, got the Fembo article with the statement of Experimenter neutrality and answered the same eight items The control students had had a mean of 51. — Bob Altemeyer, The Authoritarian Specter, 3277