Persuasion by numbers: How does numeral marking of arguments in bad news letters influence persuasion?

To what extent does numbering the reasons for a negative decision influence the persuasive force of the text? That is the focus of this study, in which we report an experiment (with 265 participants) wherein the direct effects and the indirect effects of numeral markings are analyzed in two linguistic contexts: in the introduction of the upcoming enumeration of reasons (the so-called ‘trigger’) and in the lead-ins of the successive reasons of the enumeration itself. The experiment was conducted within the framework of the Elaboration Likelihood Model (Petty and Cacioppo, 1984) and the Schematic Text Structural Expectations Hypothesis (Sanders and Noordman, 2000; Mulder, 2008). Adding numeral markers in both trigger and lead-ins turns out to enhance the persuasiveness of the text in several ways. It stimulates readers to elaborate more on the content of the reasons. It helps readers to scrutinize the reasons and stimulates recall, which contributes to a more balanced judgment. The markings also have a direct positive effect on persuasiveness, which points to an effect on low elaborating readers. Furthermore, inconsistent implementation of numeral markings (the combination of a numeral trigger with non-numeral lead-ins or a non-numeral trigger with numeral lead-ins) has a negative indirect effect on persuasiveness via text evaluation. This effect is explained by assuming that the Schematic Text Structural Expectations Hypothesis not only applies to text processing, but to text evaluation as well.