Message Properties, Mediating States, and Manipulation Checks: Claims, Evidence, and Data Analysis in Experimental Persuasive Message Effects Research

Abstract

This article addresses the conceptualization and definition of message variables in persuasion effects research. Two central claims are advanced. First, effectbased message variable definitions (in which a message variation is defined in terms of effects on psychological states, as when fear appeal variations are defined on the basis of differences in aroused fear) impede progress in understanding persuasion processes and effects and hence should be avoided in favor of definitions expressed in terms of intrinsic message features. Second, when message variations are defined in terms of intrinsic features, message manipulation checks, under that description, are unnecessary but similar measures may usefully be understood and analyzed as assessments of potential mediating states. One enduring question in communication research is how and why persuasive messages have the effects they do. But some important conceptual aspects of this subject seem to have suffered from inattention, with resulting needless confusion and impaired research progress. The particular focus of concern in this paper is the set of complex relationships among experimental message variations, message manipulation checks, persuasive outcomes, and mediating states. The purpose is to point to some systematically different sorts of research claims that arise in the context of studying persuasion effects, with an eye to clarifying the different burdens of proof—and corresponding data-analytic treatments—appropriate for each and thereby to untangling some of the complexities and confusions that have arisen in this research domain. Two central claims will emerge from this analysis: First, effect-based message variable definitions impede progress in understanding persuasion processes and effects and hence should be avoided in favor of definitions expressed in terms of intrinsic message features. Second, when message variations are defined in terms of intrinsic features, message