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Counter-Attitudinal Advocacy is particularly effective where it is difficult for the person to later deny that the dissonance-causing behavior actually took place. Thus written (and especially signed) statements and public activities can be powerful tools of persuasion. Research Festinger and Carlsmith (1959) got experiment participants to do a boring task and then tell a white lie about how enjoyable it was. Some were paid $1, others were paid $20. Later, they were asked openly how much they had enjoyed the task. Those who were paid $20 said it was boring. Those who had been paid $1 rated the task as significantly more enjoyable.
Example Counter-Attitudinal Advocacy has been extensively used for brainwashing, both with prisoners-of-war and peacetime cult members. It usually is done by making incrementally escalating requests. Small rewards are offered, which are too small for the victims to use to attribute their behavior change to, thus forcing internal attribution. References Festinger and Carlsmith (1959)