Internal Versus External Criticism of Group Standards
Sumiko Iwao
Sociometry, Volume 26, No. 4 (Dec., 1963), 410-421

The context of Festinger's theory in relation to this paper.
When an individual is confronted with an opinion contrary to his own he experiences dissonance. The cognitions corresponding to his own opinions are dissonant with [his] cognitions that other persons like himself hold differing opinion. The magnitude of the dissonance depends on the value of the issue at hand and the value of the person holding the differing opinion.

An unexpected outcome was the "delayed dissonance effect" where subjects much later sought out information on the topic.

Behaviors for reducing dissonance in the context of a disagreement
Derogate the person who disagrees.
Change one's own opinion or try to change the other person's opinion.
Convince one's self the content area of disagreement is unimportant.
Seek additional social support for one's own beliefs.
  Very few subjects expressed apprehension toward their chosen subject after the experiment.   A distinct majority of subjects in th experiment sought significantly more information following the experiment.

There was more dissonance when there were disagreements within the group than there was dissonance during disagreements between in-group and out-group members. Therefore, the added value of membership to a groups is inversely proportional to the value of an opinion from another group.

Cohesiveness of group membership predetermines the value of outside information. Extreme cases include Heaven's Gate, The Jonestown Massacre, the possible exception being the Branch Dividians in Waco Texas because false accusations of child abuse and drug manufacturing instigated the assualt that lead to their deaths. Opinion leaders at first create a fictional enemy of evil, then wait for the right moment to throw back the curtain and point their finger at someone who only needs to match two or three of the evil criteria.