Using longitudinal research designs, we examine the role of politicization in the development of polarization. We conducted research in two different political and national contexts. In Study 1, we employ a panel sample of supporters of the Tea Party movement in the United States and examine the relationship between the strength of their politicization and their subsequent feelings towards conservatives versus liberals (affective polarization) as well as their subsequent perceptions of commonalities with conservatives versus liberals (cognitive polarization). In Study 2, we employ a panel sample of members of the lesbian, gay, bisexual, transgender, and intersex (LGBTI) community in Germany and examine the politicization-polarization link with regard to feelings towards, and perceived commonalities with, feminists versus supporters of a populist right-wing political party. We obtained converging evidence suggesting that politicization promotes both affective and cognitive polarization. There was also some, but very limited evidence pointing to reverse causation. The danger of escalating polarization is discussed.
