Author ORCID Identifier

Year of Publication


Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation


Communication and Information



First Advisor

Dr. Nancy Harrington

Second Advisor

Dr. Jeannette Sutton


The extended parallel process model (EPPM) is a popular health and risk communication theory that explicates the relationship between perceived threat, perceived efficacy, fear, and adaptive and maladaptive responses. This study examines the EPPM in an imminent threat context and focuses on how warning message content influences EPPM perceptions and how these perceptions, in turn, influence both protective action and information seeking intentions.

The first objective of this study focuses on applying the EPPM to an imminent threat context by designing EPPM informed tornado and flash flood warning messages. After message pretesting with 42 undergraduate students, 312 undergraduate students completed an online experiment intended to test the effects of tornado and flash flood warning messages with high (vs. low) threat and efficacy information. Results indicate that the high threat-efficacy message led to increased feelings of perceived threat. However, message manipulations failed to exert a significant effect on perceived efficacy. Furthermore, perceptions significantly differed in terms of hazard topic, whereby the tornado warnings were perceived as more threatening and scarier than the flash flood warnings.

The second objective of this study examines the role of fear in predicting protective action intentions as a form of danger control response. Results of mediation analyses suggest that the high threat-efficacy message increased threat perceptions, which led to fear and ultimately increased protective action intentions. These results, along with recent work in the EPPM literature, suggest that fear plays a closer role in motivating behavior and may not inhibit positive decision-making as originally predicted in the EPPM.

The third objective of this study is to determine the extent to which perceived threat, perceived efficacy, and anxiety predict motivation to seek information. Information seeking is important to examine in an imminent threat context, as it is often the first action people perform upon being alerted to the existence of a hazard. Results of mediation analyses suggest that high perceived threat can lead to anxiety, which increases motivation to seek additional information. If message writers want to lessen the likelihood of information seeking, as this behavior can delay behavioral response, strong efficacy information should be included in a warning message.

By analyzing the linkages between message, perception, and outcome, this study provides theoretical and applied contributions to the EPPM and warning message design literatures, respectively. These theoretical and practical implications are discussed for all three objectives, along with limitations and future directions for this line of research.

Digital Object Identifier (DOI)

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