How must our political communications be structured in order to stimulate opinion transformation? This crucial and perennial question has gained increasing prominence in recent times. In two preregistered population-based survey experiments on prioritizing health or civil liberties during the Covid-19 pandemic in Germany (March 2021) and on vaccination duty in Austria (November 2021), we examined the influence of communication formats in connection with the degree of societal polarization on opinion formation (polarization and depolarization). Regarding communication formats, we focus on the effects of a "contestatory", "collaborative" and "open" format. Our results display a high degree of contingency: we find that in the context of lower societal polarization, engaging with counterarguments in the contestatory or collaborative format can depolarize opinions, while the open discussion format fosters polarization. By contrast, under the context of high societal polarization, it is the contestatory or collaborative format which fosters polarization. Here, only the "open" format helps to depolarize opinions.
