Exploring the Roles of Interpersonal Conversations and Received Social Support in the Persuasiveness of Messages Informed by the Extended Parallel Process Model.

Message design and message effects theories have been criticized for ignoring the influences of interpersonal, social, and contextual factors. To address this gap, the current study explores how interpersonal conversations and received social support may influence the persuasiveness of messages informed by the extended parallel process model (EPPM). In a longitudinal experiment, participants (n = 750) were randomly assigned to watch an EPPM-informed video that promotes healthy sleep behaviors or a control video. We then encouraged half of the participants to initiate conversations and seek social support in their lives and followed up with a survey after seven days. The EPPM-informed video increased intentions and behaviors among participants who had conversations in favor of healthy sleep, those who received support from friends, and those who received informational, emotional, and instrumental support. We discuss theoretical implications for strategic message design, practical applications, and study limitations.