Are two arguments always better than one?

Purpose This research aims to examine the moderating role of consumers’ persuasion knowledge (PK) on the persuasive effect of combined advertising and publicity within the same medium. The synergistic effect experienced when two messages are thus combined is reversed for readers with high PK who are first exposed to publicity then to advertising. Believability of the message is found to be a mediator within this context. Design/methodology/approach Based on a review of the appropriate literatures on PK and integrated marketing communication (IMC), this paper tests the hypotheses using two experimental studies. Findings The results of two experiments show that publicity-then-advertising yields poorer persuasion than advertising-then-publicity, especially under a high PK condition. The reduced synergistic effect of combinations of advertising and publicity is found especially when consumers activate temporary PK and/or when they have chronically high PK. A mediator for a decrease in the synergistic effect of combinations of advertising and publicity, believability, is examined. Practical implications This study contains significant managerial implications for marketing communicators about how to most effectively combine and coordinate publicity and advertising in the implementation of an IMC strategy. Originality/value Other than making a contribution to the IMCs’ literature, this research extends understanding of the power of PK within an IMC framework. The research contributes yet another extension to the original PK model of Friestad and Wright (1994) by suggesting an underlying theoretical mechanism to explain how PK works in the IMC domain.