Listening instead of reading:The influence of voice intonation in auditory health persuasion aimed at increasing fruit and vegetable intake

Purpose. In auditory health persuasion, the speaker’s speech becomes salient, as there is no visual information available. Intonation of speech is one important aspect that may influence persuasion. It was experimentally tested to what extent different levels of intonation are related to persuasion. Furthermore, self-affirmation is applied to investigate whether for some recipients the threat posed by the information in the message might become too strong to face. The topic of the health message referred to the intake of sufficient fruit and vegetables. Methods. In Study 1 (N = 130), students either listened to a health message with a low, moderate or high level of intonation. In Study 2 (N = 143), the same manipulations of intonation were applied but half of the participants were affirmed before they listened to the persuasive message. To analyze the effects, ANCOVA is used with intention to start consuming more fruit and vegetables as dependent variable. Results. Study 1 showed that among participants who perceived their own health as poor, the high intonation led to a significant drop in persuasion. In Study 2 this effect was replicated and, in addition, the drop in intention was prevented by the self-affirmation procedure. Conclusions. A high level of intonation seems to induce a strong self-threat in those for whom the information is personally relevant. To cope with this threat, a defensive reaction is mobilized. These findings suggest that it is important to take into account the influence of voice intonation when health messages on behavioral nutrition are communicated auditory