Motivated by the goal of designing interventions for softening polarized opinions on the Web, and building on results from psychology, we hypothesized that people would be moved more easily towards opposing opinions when voiced by a celebrity they like, rather than by a celebrity they dislike or by an expert. We tested this hypothesis in a survey-based randomized controlled trial in which we exposed participants to opinions that were randomly assigned to one of four spokespersons each: a disagreeing but liked celebrity, a disagreeing and disliked celebrity, a disagreeing expert, and an agreeing but disliked celebrity. After the treatment, we measured changes in the participants’ opinions, empathy towards the spokespersons, and use of affective language. Unlike hypothesized, no softening of opinions was observed regardless of the participants’ attitudes towards the celebrity. Instead, we found strong evidence of a hardening of pre-treatment opinions when a disagreeing opinion was attributed to an expert and when an agreeing opinion was attributed to a disliked celebrity. While opinion change was elusive, we observed a pronounced reduction in empathy for disagreeing spokespersons, indicating a punitive response. The only celebrity for whom empathy remained unchanged was the one who agreed, even though they were disliked. Our results could be explained as a reaction to violated expectations towards experts and as a perceived breach of trust by liked celebrities. They confirm that naive strategies at mediation may not yield intended results, and how difficult it is to depolarize–and how easy it is to further polarize or provoke emotional responses.