Speech Rate, Intonation, and Pitch: Investigating the Bias and Cue Effects of Vocal Confidence on Persuasion.

Three experiments were designed to investigate the effects and psychological mechanisms of three vocal qualities on persuasion. Experiment 1 (N = 394) employed a 2 (elaboration: high vs. low) × 2 (vocal speed: fast vs. slow) × 2 (vocal intonation: falling vs. rising) between-participants factorial design. As predicted, vocal speed and vocal intonation influenced global perceptions of speaker confidence. Under high-elaboration, vocal confidence biased thought-favorability, which influenced attitudes. Under low-elaboration, vocal confidence directly influenced attitudes as a peripheral cue. Experiments 2 (N = 412) and 3 (N = 397) conceptually replicated the bias and cue effects in Experiment 1, using a 2 (elaboration: high vs. low) × 2 (vocal pitch: raised vs. lowered) between-participants factorial design. Vocal pitch influenced perceptions of speaker confidence as predicted. These studies demonstrate that changes in three vocal properties influence global perceptions of speaker confidence, influencing attitudes via different mediating processes moderated by amount of thought. Evaluation of alternative mediators in Experiments 2 and 3 failed to support these alternatives to global perceptions of speaker confidence.