Message pretesting using assessments of expected or perceived persuasiveness: Evidence about diagnosticity of relative actual persuasiveness

Do formative assessments of the expected or perceived effectiveness of persuasive messages provide a good guide to the relative actual effectiveness of those messages? The correlational evidence usually invoked on this question is less than ideal. The most relevant evidence compares two messages’ relative standing on perceived message effectiveness (PME) and actual message effectiveness (AME) as assessed in separate samples. Across 151 such comparisons, the direction of difference in PME matched that of AME in 58% of cases (ns). Diagnostic accuracy did not differ significantly depending on the size or significance of the PME difference, the size of the PME sample, whether PME assessments came from experts or target-audience representatives, the referent of the PME assessment, or whether the PME assessment involved comparing messages.