As Part of an Experiment, a Person Is Asked to Write

As part of an experiment, a person is asked to write an essay advocating an opinion that is opposite to her own. She is given no financial incentive to do this and after completing the essay, the experimenters find that her prior attitude has shifted towards the one advocated in the essay she just wrote. The opinions of other participants in the study who received a financial incentive ($20) for writing a counterattitudinal essay did not show similar shifts. This example best demonstrates the phenomenon called

A) social loafing
B) the fundamental attribution error
C) social facilitation
D) cognitive dissonance