Nonverbal Behaviors, Persuasion, and Credibility

This study examined the relationships among nonverbal behaviors, dimensions of source credibility, and speaker persuasiveness in a public speaking context. Relevant nonverbal literature was organized according to a Brunswikian lens model. Nonverbal behavioral composites, grouped according to their likely proximal percepts, were hypothesized to significantly affect both credibility and persuasiveness. A sample of 60 speakers gave videotaped speeches that were judged on credibility and persuasiveness by classmates. Pairs of trained raters coded 22 vocalic, kinesic, and proxemic nonverbal behaviors evidenced in the tapes. Results confirmed numerous associations between nonverbal behaviors and attributions of credibility and persuasiveness. Greater perceived competence and composure were associated with greater vocal and facial pleasantness, with greater facial expressiveness contributing to competence perceptions. Greater sociability was associated with more kinesic/proxemic immediacy, dominance, and relaxation and with vocal pleasantness. Most of these same cues also enhanced character judgments. No cues were related to dynamism judgments. Greater perceived persuasiveness correlated with greater vocal pleasantness (especially fluency and pitch variety), kinesic/proxemic immediacy, facial expressiveness, and kinesic relaxation (especially high random movement but little tension). All five dimensions of credibility related to persuasiveness. Advantages of analyzing nonverbal cues according to proximal percepts are discussed.