How the voice persuades

Van Zant, A. B., & Berger, J. (2019). How the voice persuades. Journal of Personality and Social Psychology, http://dx.doi.org/10.1037/pspi0000193

Abstract: Research has examined persuasive language, but relatively little is known about how persuasive people are when they attempt to persuade through paralanguage, or acoustic properties of speech (e.g., pitch and volume). People often detect and react against what communicators say, but might they be persuaded by speakers’ attempts to modulate how they say it? Four experiments support this possibility, demonstrating that communicators engaging in paralinguistic persuasion attempts (i.e., modulating their voice to persuade) naturally use paralinguistic cues that influence perceivers’ attitudes and choice. Rather than being effective because they go undetected, however, the results suggest a subtler possibility. Even when they are detected, paralinguistic attempts succeed because they make communicators seem more confident without undermining their perceived sincerity. Consequently, speakers’ confident vocal demeanor persuades others by serving as a signal that they more strongly endorse the stance they take in their message. Further, we find that paralinguistic approaches to persuasion can be uniquely effective even when linguistic ones are not. A cross-study exploratory analysis and replication experiment reveal that communicators tend to speak louder and vary their volume during paralinguistic persuasion attempts, both of which signal confidence and, in turn, facilitate persuasion.