Let us then see what can be said about the total magnitude of dissonance in a person created by the knowledge that he said “not X” and really believes “X.” With everything else held constant, this total magnitude of disso- nance would decrease as the number and importance of the pressures which induced him to say “not X” increased.
Thus, if the overt behavior was brought about by, say, offers of reward or threats of punishment, the magnitude of dissonance is maximal if these promised rewards or threat- ened punishments were just barely sufficient to induce the person to say “not X.” From this point on, as the promised rewards or threatened punishment become larger, the magnitude of dissonance becomes smaller.
One way in which the dissonance can be reduced is for the person to change his private opinion so as to bring it into correspondence with what he has said. One would conse- quently expect to observe such opinion change after a person has been forced or induced to say something contrary to his private opinion. Furthermore, since the pressure to reduce dissonance will be a function of the magnitude of the dissonance, the observed opinion change should be greatest when the pressure used to elicit the overt behavior is just sufficient to doit.
The present experiment was designed to test this derivation under controlled, labora- tory conditions. In the experiment we varied the amount of reward used to force persons to make a statement contrary to their private views. The prediction [from 3 and 4 above] is that the larger the reward given to the subject, the smaller will be the subsequent opinion change, as a two-hour experiment dealing with ” Meas- ures of Performance.”