the tendency for members of a group discussing an issue to move toward a more extreme version of the positions they held before the discussion began. As a result, the group as a whole tends to respond in more extreme ways than one would expect given the sentiments of the individual members prior to deliberation. Polarization is sustained by social comparison (see social comparison theory), by exposure to other members’ relatively extreme responses (see persuasive arguments theory), and by groups’ implicit social decision schemes. See choice shift; risky shift.