1. Queen’s University, Kingston, Ontario, Canada
Investigating the Hypothesized Non-Linear Influence of Speech Rate on Speaker Confidence and Attitudes
Joshua J. Guyer, Leandre R. Fabrigar, Thomas Vaughan-Johnston & Nicole Seligman
Queen’s University, Kingston, Ontario, Canada
1. Abstract
4. Method
6. Results & Discussion
Participants (N = 472) listened to an audio recording that proposed strong or weak arguments in favor of working for the university in exchange for a reduction in tuition. Next, participants were asked to provide ratings of the speaker along a variety of dimensions, including speaker confidence. Participants then indicated their attitude towards the proposed tuition-reduction program. Finally, participants listed up to 10 thoughts they had while listening to the recording and rated the favorability of those thoughts to the topic. We employed a 5(Vocal speed: extremely slow, vs. moderately slow, vs. baseline, vs. moderately fast, vs. extremely fast) x 2(Argument quality: strong vs. weak) between subjects factorial. Vocal speed was manipulated using digital audio software (PRAAT©) to ensure no properties of voice other than rate of speech was altered.
Manipulation checks revealed that vocal speed and argument quality were successfully manipulated. Follow up tests using path analyses indicated that as vocal speed increased from extremely slow to baseline, this led to a corresponding increase in ratings of speaker confidence. Speaker confidence had a significant positive influence on cognitive responses, such that greater perceptions of speaker confidence resulted in more favorable topic-relevant thoughts, in turn enhancing persuasion. However, ratings of speaker confidence decreased in response to a moderately fast and extremely fast speaker. This decrease in speaker confidence translated into more negative topic-relevant thoughts, thus reducing persuasion. Taken together, under conditions that promote the increased scrutiny of a message, our data suggests that rate of speech has a non-linear influence on perceptions of speaker confidence such that speaking too fast can reduce perceptions of confidence which in turn negatively biases cognitive responses and erodes the success of a persuasive appeal.
Participants.
472 undergraduate psychology students participated in return for course credit
5(Rate of speech: extremely slow vs. moderately slow vs. baseline vs. moderately fast vs. extremely fast) x 2(Argument quality: strong vs. weak) between participants factorial.
After being seated at a computer, all participants were given headphones and instructed to listen to an audio passage that presented moderate arguments in favor of working for Queen’s university in exchange for a reduction in tuition. After listening to the audio recording, participants were asked to provide ratings of the speaker along a variety of dimensions, including rate of speed and speaker confidence. The presentation order of these questions were randomized. Participants then completed a measure assessing their attitudes towards the topic. Finally, a cognitive response tasking was presented in which participants listed up to 10 thoughts about the topic and then rated the favorability of their thoughts.
All questions used 7-point rating scales.
Vocal Speed Manipulation Check:
Confirming expectations, an ANOVA revealed each level of speech rate was perceived as significantly different than the previous level, F(4, 462) = , p < .001, partial η2 = .68, (see Figure 1).
Vocal Confidence Manipulation Check:
Confirming expectations, an ANOVA revealed a significant main effect of vocal speed on ratings of speaker confidence, F(4, 462) = 20.42, p < .001, partial η2 = .15. As anticipated, pairwise comparisons using the LSD test indicated the effects of speech rate on ratings of speaker confidence increased in a linear fashion as rate of speech progressed from extremely slow (M = 3.63, SD = .15), to moderately slow (M = 4.82, SD = .53), p < .001, to baseline (M = 5.34, SD = .15). No different in speaker confidence was found when comparing baseline with moderately fast speech rate (M = 5.19, SD = .15), p < However, a decrease in speaker confidence was revealed when comparing an extremely fast speech rate (M = 4.53, SD = .15), with both a moderately fast, p < .01 and baseline rate of speech, p < These data reveal a pattern of effects that fit with our hypothesis that rate of speech does not necessarily have a linear effect on judgements of speaker confidence, (see Figure 2).
Argument Quality Manipulation Check:
Confirming expectations, an ANOVA revealed a significant main effect of argument quality, F(1, 462) = , p < .001, partial η2 = .33, such that attitudes toward the university service plan were significantly more favorable following exposure to strong (M = 4.89, SD = .08), compared with weak arguments (M = 3.15, SD = .08), (see Figure 3).
The Effects of Speech Rate on Attitude:
Results of an ANOVA indicated a marginally significant main effect of speech rate on attitude, F(4, 462) = 2.25, p = .06, partial η2 = .02. Pairwise comparisons revealed no difference in attitude when comparing the baseline (M = 4.23, SD = .13), with moderately fast rate of speech (M = 4.17, SD = .13), p = .77. However, relative to baseline, an extremely fast rate of speech led to significantly less favorable attitudes (M = 3.80, SD = .13), p < .02. This was also true when comparing an extremely fast rate of speech with a moderately fast rate of speech, p < Interestingly, a symmetrical effect of speech rate on attitude was revealed on the other end of the speech rate continuum. That is, no difference in attitude was found when comparing the baseline with a moderately slow rate of speech (M = 4.05, SD = .13), p = .32. However, relative to baseline, an extremely slow rate of speech led to significantly less favorable attitudes (M = 3.88, SD = .13), p < .04. This was also true when comparing an extremely slow rate of speech with a moderately slow rate of speech, p < .04, (see Figure 4). No speech rate x argument quality interaction was anticipated and none emerged, F(4, 462) = 1.03, p = .39, partial η2 = .01. No interaction was found between rate of speech and argument quality, F(4, 462) = 1.03, p = .39, partial η2 = .01.
The Effects of Vocal Confidence on Attitude:
As anticipated, the data revealed speech rate had the expected effect on ratings of speaker confidence (see Figure 5). Next, increased confidence should bias a person’s thoughts to be more positive towards the message. This is exactly what the data shows. Thoughts should have a powerful impact on a person’s attitude. Once again, the data confirms this is correct. The final path evaluates the direct effect of speaker confidence on attitudes. Because this is high elaboration situation, the ELM predicts speaker confidence should not have a direct impact on attitudes by functioning as a cue. As expected, this is what we find. Taken together, these results suggest that when carefully processing a message, individuals use their judgements of a speaker’s vocal confidence as a determinant of the positivity or negativity of their thoughts, which then have a corresponding effect on their attitude toward the message.
Design.
Procedure.
Measures.
5. Results
Figure 1.
Figure 2.
2. Introduction
Although a great deal of research has looked at those variables that influence persuasion, one area that hasn’t received a lot of attention are the different properties of a speaker’s voice. This is somewhat surprising because so much of communication and of course persuasion takes place orally. We know that beyond the content of what we say, our voice also contains a rich variety of information, so intuitively it makes sense that how we say something should also play a role in how successful we are at persuading others. Now while there are certainly lots of characteristics of voice that matter, one characteristic that intuitively should affect the persuasion process is how confident the speaker is perceived to be.
For example, research has found that confident speakers talk louder (Kimble & Seidel, 1991; Scherer, London, & Wolf, 1973), finish their sentences using falling vs. raised intonation (Brennan & Williams, 1995; Smith & Clark, 1993), and speak faster (Miller, Maruyama, Beaber, & Valone, 1976; Scherer et al., 1973), relative to unconfident speakers. Although a small body of research has demonstrated that various qualities of voice are related to perceptions of speaker confidence, few studies have investigated the role of speaker confidence in the persuasion process. To date, empirical investigations of this relationship have focused only on a narrow spectrum of rate of speech (Miller, et al., 1976; Smith & Shaffer, 1995). For instance, Miller et al., (1976) demonstrated that a message spoken at a rapid rate of speech generated significantly more persuasion compared with a slower version of the same message. Later research by Smith and Shaffer (1995) qualified this finding with data suggesting an interaction between speech rate and argument quality.
While the effects of vocal speed on persuasion have been investigated under moderate levels of elaboration (Smith & Shaffer, 1995), research has not examined how vocal qualities might influence attitude change when people are pushed to be under either high or low levels of processing. Thus, we sought to test how judgements of speaker confidence are influenced across a broader range of speech rate, and further, how these perceptions of confidence influence attitudes when people are carefully processing a message. Our predictions regarding how voice affects persuasion are drawn from the elaboration likelihood model.
Figure 3.
Figure 4.
Figure 5.*
7. Future Directions
3. Present Study
Investigating whether vocal intonation influences confidence and persuasion via similar mechanisms under high-thought conditions.
Investigating mechanisms by which a broader spectrum of each vocal property influences persuasion under moderately thoughtful conditions.
Goals: Test the effects of a broader range of speech rate on judgements of speaker confidence and attitude.
Determine whether speaker confidence is responsible for the effects of speech rate on persuasion and the nature of this relationship.
*Figure 5. Coefficients for each speech rate path reflect comparison with baseline speech rate. All coefficients unstandardized.
Solid lines indicate significant paths. Dotted lines indicate non-significant paths.
Contact Information: Joshua J. Guyer –