model that places the consensus policy midway between the policies of the rhetorically closest dyad. 

We conducted an experiment in which triads engaged in online discussion about wagering on National Football League (NFL) games where the outcome of concern was not the winner of the game but whether or not the margin of victory of the favorite team exceeds the oddsmakers’ point spread. The results showed (1) a signif- icant risky shift only on one policy side, and significantly greater shifts for (2) high disagreement over low and (3) complete networks over chains. The first result, in particular, runs directly counter to existing theories, which expect polarization for groups with homogeneous inclinations. These results, however, not only accord with our qualitative theoretical predictions but are also in quantitative agreement with the RPM model. 

We also present a micro-level model, the “accept-shift-constrict” (ASC) model that describes opinion change processes over a network as group members exchange messages. These processes consist of, first, the acceptance of a persuasive message which can then lead to a shift in the receiver’s opinion and, importantly, a constric- tion of their uncertainty level — this in turn narrows the extent to which subsequent messages advocating distant opinions are accepted. In combination with RIA, the ASC model is in qualitative and quantitative agreement with our experimental re- sults. Even without RIA, ASC represents a new model of opinion network dynamics in which the persistence of majority positions is enhanced via mutual uncertainty reduction among those with similar opinions, a dynamic absent from standard con- tinuous opinion models (DeGroot 1974; Friedkin and Johnsen 2011; Lorenz 2007). The RIA-ASC combination allows for shifts toward the extreme to arise without re- liance upon systematic skews in resistance to persuasion as commonly assumed within the opinion network modeling literature. 

