The Extended Parallel Process Model
 
    Witte's (1992a) Extended Parallel Process Model (EPPM) traces its lineage through the classic fear appeal theories.  Leventhal's (1970) model forms the basis of the theory, PMT explains the danger control side of the model (Rogers, 1975, 1983), and portions of Janis (1967) and McGuire's (1968, 1969) explanations can be accounted for under the fear control side of the model.  The EPPM attempts to explain both when and why fear appeals work, as well as when and why they fail.
    The variable that tends to be most problematic in fear appeals is fear.  Fear can be a barrier to behavior change, as when people are so frightened that they cannot act (so they deny or defensively avoid a threat), or a motivator to change, as when people perceive a risk and are motivated to reduce it.  According to the EPPM, the evaluation of a fear appeal initiates two appraisals of the message, which result in one of three outcomes (see Figure 1).  First, individuals appraise the threat of the hazard from the message.  The greater and more relevant the threat depicted in a message, the more individuals believe they are susceptible to a serious threat and the more motivated they are to begin the second appraisal, which is an evaluation of the efficacy of the recommended response in the message.  If the threat is perceived as irrelevant or insignificant, then there is no motivation to process the message further, and people simply ignore the fear appeal.
 
 
 

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     In contrast, when the threat is portrayed as and believed to be serious and relevant (e.g., "I'm susceptible to contracting a terrible disease"), individuals become scared.  Their fear motivates them to take some sort of action -- any action -- that will reduce their fear.  There are two general paths people take when they become frightened from a fear appeal.  People can become motivated to control the danger of the threat or people can become motivated to control their fear about the threat.  When people are motivated to control the danger, they consciously think about the fear appeal and think of ways to remove or lessen the threat.  Typically, they think carefully about the recommended responses advocated in the persuasive message and adopt those as a means to control the danger.  Alternatively, when people are motivated to control their fear, they no longer think about the fear appeal or danger of the threat.  Instead, they focus on how frightened they feel and they attempt to get rid of their fear through denial (e.g., "I'm not at-risk for getting genital warts, it won't happen to me"), defensive avoidance (e.g., "this is just too scary, I'm simply not going to think about it"), or reactance (e.g., "they're just trying to manipulate me, I'm going to ignore them").
     Perceived efficacy (composed of self-efficacy and response efficacy) determines whether people will engage in danger control or fear control processes.  People engage in danger control processes when they believe messages that emphasize how easy, feasible, and effective the recommended response is in averting a serious and relevant threat.  Thus, high efficacy messages making people feel able to perform an effective recommended response coupled with high threat messages making people believe they are vulnerable to a significant threat promote danger control responses such as adoption of the message's recommendations (e.g., "I know I can use condoms every time I have sex to decrease my chances of getting genital warts.  I'm going to keep some in my purse.").
     When messages emphasize a threat but either do not address efficacy issues or portray the recommended response to be too difficult, too costly, too time consuming, or as ineffective in averting the threat, then people will give up on trying to control the danger (because they think it would be futile to do so) and, instead, they will control their fear.  Thus, absent or low efficacy messages coupled with high threat messages promote fear control responses such as denial, defensive avoidance, or reactance which result in rejection of the message's recommendations (e.g., "I can't use condoms and even if I did they wouldn't work anyway so I might as well not think about genital warts").
     In sum, threat messages determine the extent of a response (i.e., how strong the danger or fear control responses are), while efficacy messages (or lack thereof) determine the nature of the response (i.e., whether danger or fear control responses are elicited).  If no information regarding the efficacy of the recommended response is given, individuals will rely on past experiences and prior beliefs to determine perceived efficacy.  It is critical to note for the purposes of the meta-analysis that the dimensions of threat (i.e., severity and susceptibility) are additive, as are the dimensions of efficacy (i.e., response efficacy and self-efficacy).  However, the relationship between threat and efficacy is proposed to be multiplicative.
     Thus, according to the EPPM, in some cases messages arousing fear can lead to adaptive and life-saving actions (i.e., danger control processes) and in others they can lead to maladaptive and potentially life-threatening actions (i.e., fear control processes).  As long as one perceives him or herself able to effectively avert the threat through the recommended response, very high fear levels can be induced.  However, the second one begins to doubt his or her ability to engage in the recommended response and/or begins to doubt the effectiveness of the recommended response, then fear appeals can produce strong maladaptive effects.

For examples of items from this model, see   http://www.nnlm.nlm.nih.gov/pnr/eval/witte.html.
For citations of studies examining this model, see http://www.msu.edu/~wittek/vita.htm.