“…Subjects may be eager and cooperative, bored, or vindictive and intent on sabotaging the investigation (Allen, 1966;Baumrind, 196 1 1;Brock & Becker, 1966;Fillenbaum, 1966;Goldberg, 1965;Holmes, 1967;Kelman, 1967;MacKinney, 1955;Masling, 1966;Milgram, 1964;Riecken, 1962;Vinacke, 1954). Considering the many possible differences in the perceptions and motivations of suspicious subjects, the only certainty is that their disbelief increases extraneous variation in a study (Kelman, 1967).…”