Polarization in communications and psychology, is the definition given to the behavior of a social or political group to split based on opposing views. Over time, more and more members of the original group join one or the other split group and fewer and fewer members remain neutral. This brings the two sides or "poles" further and further apart.
During polarization, there is a tendency for the opposing sides of the argument to make increasingly disagreeable statements, thereby creating more and more distance between the two sides. This is known as the "pendulum effect". Thus, it is commonly observed in polarized groups that judgments made after group discussion on a given subject tend to be more extreme than judgments made by individual group members prior to the discussion.
This process is also known as 'group polarization'. In the past, it was referred to as the 'risky shift phenomenon' and particularly referenced decision-making by a jury.