Phenomenon causing people to change their opinion when they are asked to hypothetically defend an opposing viewpoint? I remember reading a case study on this years ago and I am trying to track it down.

The study involved asking people who held strong opinions on varied subjects to defend the opposite opinion in a hypothetical debate.  At the end of the debate the people had come to adopt the viewpoint they were defending, regardless of the hypothetical nature of the actual debate.

Does anyone know the name of this phenomenon, or better yet, have a link explaining it?
Fazio et al (1977) provide a review of some of the literature on attitude change that can be induced by getting participants to take on another perspecive. To quote the opening paragraph.


  If an individual freely chooses to perform a behavior which is
  discrepant from his attitude, he tends later to realign his attitude
  toward that behavior. For example, a subject who complies with an
  experimenter’s request to write an attitude-discrepant essay against
  the legalization of marijuana is typically found to favor such
  legalization to a lesser degree than previously. This now classic
  attitude change effect is readily explained by both Festinger’s theory
  of cognitive dissonance (1957) and Bem’s self-perception theory
  (1972). Dissonance theory, in general, concerns the relationship
  between various cognitions. The theory posits the existence of a
  drive-like motivation to maintain consistency among relevant
  cognitions. Self-perception theory, on the other hand, concerns the
  passive inference of attitudinal dispositions from behavior. According
  to Bem (1972), “Individuals come to ‘know’ their own attitudes,
  emotions, and other internal states partially by inferring them from
  observations of their own overt behavior and/or the circumstances in
  which this behavior occurs” (p. 2). Social psychologists vary in which
  theory they endorse.


References


Fazio, R. H., Zanna, M. P., &amp; Cooper, J. (1977). Dissonance and self-perception: An integrative view of each theory's proper domain of application. Journal of Experimental Social Psychology, 13(5), 464-479. PDF