Testing the evidence effect of Additive Cues Model (ACM)

Since Aristotle, evidence provides a means of support to justify the acceptance of a conclusion. Textbooks used to teach persuasion in courses like public speaking often note the independent importance of speaker credibility, message evidence, and reasoning without necessarily considering the additive persuasive impact of the elements. Advice on how to persuade others requires consistent updating with empirical testing. The current study tests the Additive Cues Model (ACM; Kim et al., 2012, Kim et al., 2014a) to examine whether increasing the amount of evidence contributes to message persuasiveness in the context of global warming. Contrary to prediction offered by the ACM, the current data show that anti-global warming beliefs do not necessarily increase as anti-global warming evidence increases. Instead, the results present preliminary evidence that the ACM may be used to predict a persuasive boomerang for individuals with high issue involvement on the topic.