Ambiguity Undermines Persuasive Effectiveness: Ego Involvement, Motivated Reasoning, and Message Ambiguity

Motivated reasoning is a form of biased processing where people evaluate messaging in such a way that it allows them to confirm their preexisting beliefs. The self-concept approach to motivated reasoning assumes that ego involvement drives this process, such that greater ego involvement leads to greater post-message dissonance and increases the likelihood of motivated reasoning. However, the theoretical framework proposes that motivated reasoning can be mitigated when message ambiguity is minimized. Across two experiments, we tested components of the self-concept approach to motivated reasoning, including this ambiguity principle. In general, the results did not provide support for the framework or the ambiguity principle. However, the direct effects of ambiguity suggest that it dampens the persuasiveness of messages. We consider what these results mean for the self-concept approach to motivated reasoning, theorizing about message ambiguity, and designing real-world messages that minimize ambiguity.