and Nakanishi 2002). Consequently, when faced with a given group with a specific opinion distribution, standard theory cannot readily predict what effect polarization mechanisms will have on the outcome, even when the conditions for their activation are met. The second question of concern, how group polarization is affected by communi- cation network structure, has received little attention. Communication in real-world decision-making groups is often concentrated within subgroups due to friendship, factional, or functional divides; covert groups may impose a more limited network structure upon themselves to minimize detection. Only one previous study has ex- perimentally investigated group polarization with respect to different communication network topologies: no effect of topology was reported although the polarization effect itself was largely absent (Friedkin 1999). The final question involves the reference point itself, intrinsic to the very definition of group polarization. Although its initial discovery was instrumental in empirically anticipating whether groups would undergo risky or cautious shifts (Brown 1986), the switch to the experimental use of Likert scales with defined neutral points helped marginalize the reference point as a theoretical concern. However, in natural decision- making settings, such as foreign policy crises, it is not always clear as to where the reference point should be set. No broad guidance governing reference point selection criteria exists and, as our experimental results reveal, even the obvious choice can be misleading. Other accounts of group polarization beyond the informational and normative the- ories have been subsequently proffered but have not received as intense experimental scrutiny (McGarty et al. 1992; Zuber, Crott, and Werner 1992; Ohtsubo et al. 2002). One explanation, which we refer to as “extremist-tilting,” attributes group polariza- tion to traits, such as stubbornness or confidence, of extremists themselves that give 6