The persuasive power of not-at-issue speech

It is commonly assumed that not-at-issue speech is more persuasive than at-issue speech because it is exploited by those who are incentivized to persuade. Empirical work supports this assumption. An important question, then, for those interested in understanding and combating the spread of misinformation, is why content is more persuasive when presented as not-at-issue. I argue that commonly proposed normative explanations are inadequate and draw on work in discourse theory and cognitive science to offer a new, broadly cognitive one: not-at-issue speech is attended to less than at-issue speech because of its subordinated position in discourse structure. It is more persuasive because it is processed under load, and under such conditions people are prone to make mistakes. We err on the side of belief rather than disbelief because rejection is more effortful than belief.