Changing Conceptions of "Message Effects" A 24-Year Overview

Jackson and Jacobs (1983) argued for three changes in the conduct of message effects research: inclusion of multiple message replications as instances of a treatment, recognition of message replications as a source of random variation in the estimation of treatment effects, and attention to issues of message sampling. This review updates their argument and examines 24 years of research published in Human Communication Research for evidence of attention to these recommendations. The review shows the following: the prevalence of studies failing to replicate has declined, replications are still rarely recognized as random factors, and researchers who use replications appear to do so for purposes of generalizability and control over confounding but without carefully analyzing the burden of proof associated with those purposes. An explicit framework for discussion of treatment effects in communication is proposed as an advance over the original reasoning of Jackson and Jacobs.