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CHAPTER 14
Inoculation Theory
Josh Compton
After Michael Pfau and I offered what was, prior to this chapter, the most comprehensive narrative review of inoculation scholarship (Compton & Pfau, 2005), we concluded that inoculation, while a mature theory, was “far from retiring” (p. 136). We predicted prodigious theory development and application, and as this review will show, this happened and is happening. Researchers continue to propel inoculation scholarship forward in quantity and theoretical depth. Some scholarship confirms findings from the first years of the theory; other discoveries challenge fundamental assumptions about resistance in general and inoculation theory in particular. And all the while, the original analogy is pulled and stretched.
Inoculation theory maintains a complicated relationship with its analogical namesake. More than rhetorical flourish, the analogy was intended to serve, in the words of its creator, as inoculation’s “theoretical point of departure” (McGuire, 1964, p. 222). There is a logic in analogy—an analogic (Holyoak & Thagard, 1995, p. 2) unique to theorizing with analogy—that, in inoculation theory, weaves biological resistance processes with persuasion resistance processes. While some resistance dynamics line up neatly, others have looser connections, and still others seem, at least at first glance, to be independent of the analogy. Although one-to-one connections between characteristics of sources and targets are not requirements for analogical transfer, when they are present, they are useful (Holyoak & Thagard, 1995). After identifying purported gaps between the two resistances, some have called for reconsideration of the analogy (e.g., Wood, 2007).
Because of the historical and contemporary importance of the analogy in inoculation theory’s story, the analogy will never be far from our considerations in this chapter. Initially, the chapter focuses on how the early model of inoculation held tightly to the analogy to explain how inoculation confers resistance. After considering how, the chapter turns to where by tracing inoculation theory’s applications in health, politics, and commerce. Next, the basic model and its analogical premises are confronted in a survey of some of the most important contemporary issues facing the theory as the chapter outlines analogical connections with mediators, moderators, and outcomes. The chapter concludes with a suggested agenda for the next generations of inoculation scholarship—an agenda that recognizes and challenges inherent assumptions of the analogy.
The Basic Model
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McGuire (1964) named and explained his resistance model with a medical analogy, noting how persuasion inoculation parallels medical inoculation. Consider, for example, an annual flu shot. A flu shot injects weakened versions of influenza virus—weakened to avert infection but strong enough to activate resistance. In a medical inoculation, resistance results from protective responses, such as the production of antibodies, triggered by threat. Similarly, during persuasion inoculation, pretreatment messages offer weakened versions of counterarguments—again, weakened to prevent persuasion but strong enough to activate protective responses. In a persuasion inoculation, resistance results from protective responses, such as the production of refutations to counterarguments, triggered by threat (McGuire, 1964). In both cases, resistance mechanisms, motivated by threat, confer protection against future attacks.
In this basic model, we find tight connections between medical and persuasion inoculations. Future threatening viruses are linked to future threatening persuasive challenges; weakened viruses reflect weakened counterarguments; and antibodies that come to the rescue in medical inoculations mirror refutations during persuasion inoculations. Under the assumptions of the basic model of inoculation theory, the medical analogy is explicatory. It neatly serves as an explanation for inoculation-conferred resistance that is as simple—or, as we would later discover, as complex—as we wish.
The prototypical inoculation pretreatment is a two-sided message, often called a refutational pretreatment, to contrast with a one-sided message, or supportive pretreatment (McGuire, 1964). To return to the medical analogy: An example of a supportive pretreatment against the threat of disease would be a vitamin regimen—a way to boost health before facing a potentially harmful virus (McGuire, 1964). In contrast, refutational pretreatments raise persuasive challenges: counterarguments, or arguments that challenge existing positions, beliefs, or attitudes. These counterarguments are weakened by refutations—becoming like weakened viruses in some medical inoculations (McGuire, 1964).
McGuire and his colleagues designed a series of experiments in the early 1960s to compare resistance conferred by refutational pretreatments to other pretreatments (e.g., supportive) or to no pretreatments (no message-control). Refutational pretreatments were superior in conferring resistance to subsequent challenges (McGuire, 1964).
Demonstrating resistance requires some inverted logic. Tests must confirm persuasion in order to assess resistance. So, as with tests of persuasion, inoculation studies need to show that the attack message used in the study was actually persuasive. But with resistance research, the key question is whether a pretreatment rendered the attack less persuasive. McGuire’s standard research design—and most subsequent research designs in contemporary inoculation scholarship—enables this type of scrutiny: All participants are exposed to an attack message or messages, but only some receive pretreatment messages prior to the attack. This design allows researchers to assess whether the attack was actually persuasive and to assess whether the pretreatment (e.g., the refutational inoculation message) mitigated the persuasiveness of the attack.
This design allowed for comparisons of inoculation and control conditions, and also, different types of resistance pretreatments. For example, McGuire and his colleagues compared refutational-same and refutational-different inoculation pretreatments. Refutational-same raise and refute the same arguments that later are used in the attack message; refutational-different raise and refute novel arguments, not included in the attack. Both approaches confer resistance, which means that inoculation is not limited to refuting the same arguments later used in the attack (McGuire, 1964).
McGuire’s inoculation theory offered a more nuanced understanding of the resistance effect of two-sided messages. Researchers had confirmed that two-sided messages could offer “an advanced basis for ignoring or discounting [opposing messages]” and that this preparation somehow “inoculated” recipients (Lumsdaine & Janis, 1953, p. 318). McGuire’s theory moved past that refutational pretreatments work into how refutational pretreatments work. And an explanation of how, consistent with the basic model derived from the analogy, turns attention to threat and counterarguing—a catalyst (threat) and an activity (counterarguing) of inoculation-conferred resistance.
Threat and Counterarguing
Threat
Threat in inoculation is not a message property, but instead, a response to a message. It is recognized vulnerability, a perception that an existing position, once thought safe from change, may be at risk. In medical inoculation, the presence of an antigen motivates antibody production. In persuasion inoculation, we find something similar: The mere presence of unexpected challenges to an existing position, or counterarguments, threatens perceived security of that existing position. McGuire called this threat implicit threat (McGuire, 1964).
We also find an additional threat motivator in many inoculation messages: a forewarning of impending persuasive attacks. In McGuire’s terms, this is explicit threat (McGuire, 1964). In most inoculation studies, a forewarning comes at the beginning of the inoculation message, although recent studies have used forewarnings at the end of a message, too (e.g., Ivanov et al., 2011). Regardless of where the forewarning oc
curs, the basic message is: Although you currently hold the right position on this issue, you will face future persuasive attacks, and such challenges may change your position. With both types of threat—implicit and explicit—potential vulnerability is exposed, motivating a process (or, as we later discovered, processes) of resistance.
Counterarguing
The collective generation of counterarguments and refutations, post-inoculation pretreatment, is a process called counterarguing. It is important to distinguish this conceptualization of counterarguing with material in an inoculation pretreatment. A pretreatment message does, indeed, present counterarguments and, usually, refutations, as a two-sided approach. But counterarguing as a process extends the argumentation modeled in pretreatment messages to activity after the pretreatment. Something dynamic happens: Those inoculated begin to counterargue on their own, raising and refuting additional arguments about the issue (see Compton & Pfau, 2005, McGuire, 1964). This process of counterarguing—modeled in the pretreatment and then continued—is tightly connected to our medical analogy. Refutations function much like antibodies, attacking and weakening offending antigens.
This is the basic model of inoculation-conferred resistance to influence: raising and refuting challenges confers resistance to future stronger challenges by (1) revealing vulnerability of the position (threat) through an explicit forewarning and/or the presence of counterarguments, which motivates (2) counterarguing (i.e., raising and refuting additional arguments about the issue in addition to arguments in the pretreatment).
Study after study in the 1960s confirmed that inoculation confers resistance to persuasion (McGuire, 1964). Yet, two unresolved limitations likely impeded inoculation’s development in the immediate years following its introduction: (1) a lack of empirical confirmation of how inoculation conferred resistance (e.g., threat and counterarguing); and (2) the restricted use of inoculation with cultural truisms.
The analogy bore the burden of explaining inoculation. A weakened offending antigen threatens, which motivates a protection response—in biology and, McGuire reasoned, in persuasion. And yet, threat was only assumed in the early years of the theory (Compton & Pfau, 2005). Counterarguing was treated similarly to threat—also assumed, for the most part. One study (Papageorgis & McGuire, 1961) attempted to measure counterarguing by having participants make a list of arguments that supported their position, but this way of assessing post-inoculation cognitions did not support inoculation’s effect on counterarguing.
Threat and counterarguing fit the logic (or analogic, Holyoak & Thagard, 1995) of the analogy, but in early research, lacked empirical support as explanatories. However, beginning with Pfau and Burgoon (1988) and continuing through recent inoculation scholarship, scholars have measured elicited threat and post-inoculation counterarguing. The most commonly used threat measure is a Likert-type scale with items such as nonthreatening/threatening and not harmful/harmful (e.g., Ivanov et al., in press). Counterarguing is often assessed using some variation of thought listing (i.e., asking participants to put into words thoughts that went through their heads; e.g., Parker, Ivanov, & Compton, 2012). Confirmation of threat and counterarguing helped propel inoculation scholarship forward, encouraging inoculation’s resurgence as an active research program in the late 1970s (led by M. Burgoon and colleagues) and then again in the 1990s (led by Pfau and colleagues).
Scholars clarified threat and counterarguing, but what of inoculation’s perceived restriction to cultural truisms? McGuire’s early work with inoculation did not advance beyond cultural truisms, or “beliefs that are so widely shared within the person’s social milieu that [the person] would not have heard them attacked, and indeed, would doubt that an attack were possible” (McGuire, 1964, p. 201). McGuire chose cultural truisms as the issue domain of inoculation to keep, as close as possible, the analogy connection. Cultural truisms represented “a ‘germ-free’ ideological environment” (McGuire, 1964, p. 200), and this, he reasoned, enabled tests of resistance with issues people had never heard attacked and avoided complications suggested by selective exposure predictions. Early inoculation studies explored issues such as teeth brushing and benefits of penicillin.
McGuire’s decision to use cultural truisms limited inoculation’s application to noncontroversial issue domains—by design. But later, Pryor and Steinfatt (1978) challenged McGuire’s reasoning that restricted inoculation to cultural truisms, pointing out that an application to controversial issues remains consistent with the analogic, so long as new counterarguments are raised in the inoculation message. Their interpretation allowed extensions of inoculation beyond the boundaries of uncontended issues (cultural truisms), while remaining consistent with the analogic. A survey of subsequent inoculation scholarship shows inoculation’s success with a wide-range of controversial issues, including legalizing marijuana (e.g., Pfau et al., 2009), banning testing on animals (Nabi, 2003), and support for U.S. involvement in the Iraq War (Pfau et al., 2008). Building from the basic model and confirming its efficacy against more provocative issues paved the way for dynamic applications of inoculation—particularly in health, politics, and commerce.
Applications of the Theory
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Health
Inoculation theory’s application to health issues is apt, if in name only. Indeed, even when inoculation theory was restricted to cultural truisms, its earliest studied issues were often health-related (e.g., dental hygiene, X-rays). But inoculation’s potential as an applied health strategy was more fully realized when it was extended beyond the laboratory and into the field (see Ivanov, 2011). No health issue demonstrates this better than inoculation-informed antismoking campaigns. Not only did inoculation help children with low-self esteem resist pressures to smoke (Pfau, Van Bockern, & Kang, 1992), but also some attitudinal effects lasted 20 months after inoculation pretreatments (Pfau & Van Bockern, 1994). This ground-breaking study set precedence for using inoculation to inform health campaigns, and it offered a more focused approach than Richard Evans’ social inoculation (see Wallack & Corbett, 1987), which uses multiple activities—often employing refutational messages—but fails to measure the key variable of threat.
Building from inoculation’s established efficacy as a preventative strategy with smoking, Godbold and Pfau (2000) found inoculation also helped children combat alcohol influences. Specially designed normative inoculation messages gave children a more accurate perspective of how many of their peers were drinking, although inoculation did not enhance attitudinal resistance to alcohol advertising, perhaps because researchers weren’t able to elicit more threat with the inoculation condition (Godbold & Pfau, 2000). Parker, Ivanov, and Compton (2012) found inoculation conferred resistance to challenges to college students’ condom use attitudes. They also found a cross-protection effect: Inoculating against challenges to condom use attitudes also conferred protection of binge drinking attitudes.
Politics
Applied research confirms inoculation offers an effective, innovative political campaign strategy—a preemptive approach to protect image and secure votes (see Pfau & Kenski, 1990). Inoculation preempts effects of attacks on candidate image and their positions (Pfau & Burgoon, 1988; Pfau, Kenski, Nitz, & Sorenson, 1990), including attacks raised in debates (An & Pfau, 2004), and its effects extend beyond attitudes and into intended actions—with some voters, boosting likelihood of voting and information seeking (Pfau, Park, Holbert, & Cho, 2001). Other research explores inoculation’s effects on specific political issues. Pfau and his colleagues assessed inoculation’s efficacy in securing support for U.S. involvement in Iraq against the influence of photographs (Pfau, Haigh, Fifrick, et al., 2006) and news visuals (Pfau, Haigh, Shannon, et al., 2008). Inoculation reduced influences of photographs, but only with females (Pfau et al., 2006); against news visuals, inoculation boosted threat and counterarguing but did not impact attitudes (Pfau et al., 2008). Turning their attention specifically to inoculation’s effects on political dialogue, Lin and Pfau (2007
) confirmed its efficacy against spiral of silence effects, or the stifling effect of perceiving that one’s opinion is in the minority (see Noelle-Neumann, 1993). Inoculation boosted confidence, encouraged speaking out, and bolstered positions against challenges (Lin & Pfau, 2007).
Commerce
Inoculation can inform corporate communication, public relations, and marketing. Inoculation messages in employee literature bolster organizational identity, commitment, conscientiousness, and sportsmanship (Haigh & Pfau, 2006); corporate issue-advocacy campaigns have inoculative effects (Burgoon, Pfau, & Birk, 1995); and precrisis inoculation protects image after a crisis (Wan & Pfau, 2004; Wigley & Pfau, 2010b).
Inoculation can either help or thwart marketing. Companies can inoculate against their competitor’s comparison ads with higher-involving products (Pfau, 1992) and can inoculate against attacks based on country-of-origin (COO), even when multiple attacks are launched (Ivanov, Pfau, & Parker, 2009a). But inoculation can also help consumers resist marketing efforts. Inoculating against front-group stealth campaigns (groups of companies with misleading, innocuous names) protects against their influence (Lim & Ki, 2007; Pfau et al., 2007), and inoculating against credit card marketing protects college students from some potentially negative effects (Compton & Pfau, 2004).
Clearly, inoculation’s efficacy is not restricted to cultural truisms. In health, politics, commerce, and a host of other domains (some of which remain unexplored or underexplored), inoculation confers resistance to influence. And often, applied findings are consistent with McGuire’s original theorizing: Inoculation messages elicit threat, boost counterarguing, and confer resistance.
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