In order to avoid a common pitfall of humor research, empirical description with very little theoretical basis, this research provides grounded predictions based on established theory. The theory of persuasion is reviewed and then related to the theory of humor to generate specific propositions about when and how humor will be effective in persuasion. Then these predictions are tested experimentally.




PERSUASION THEORY


Daniel O'Keefe (1990) defines persuasion as a successful intentional effort at influencing another's mental state through communication in a circumstance in which the persuadee has some measure of freedom.

This definition captures the main elements that people take to identify an instance of persuasion. For example, only a successful attempt to persuade counts as persuasion. It would make no sense to say, I persuaded him, but he wouldn't come around to my way of thinking. Further, only when a receiver has freedom of choice, can we say that persuasion is being used instead of coercion.

Although some would argue that the final goal of most persuaders is to change behavior rather than just mental states (e.g., Funkhouser & Parker, 1999), these changes are generally achieved through a person's mental state and, specifically, attitude. Directly controlling another's behavior is rarely appropriate in a democratic society.

The existence of interpersonal communication is a given in persuasion research. Although one could conceivably be persuaded by the facts alone (without the intervention of a source), that would generally be characterized as learning rather than persuasion.

The only controversial aspect of the above definition is the inclusion of the word intentional. It seems to this writer that receivers who overhear an argument and find it convincing have been persuaded, even though the source never intended to convince them. However, this quibble with the definition need not affect its adoption here.



FIGURE 6
Components of Persuasion


SITUATION ---> SOURCE ---> MESSAGE ---> RECEIVER



In a given situation, persuasion begins with the communication of a message by a source. This message consists of an idea discrepant from the receiver's ordinary beliefs. This presumably creates dissonance within the receiver (Festinger, 1957), who then seeks relief. Relief can be gained by refuting the source's arguments, derogating the source, distorting the message, rationalization, or blanket refutation. The goal of the source, then, is to block these alternate responses so that the receiver will prefer to relieve the dissonance by simply accepting the new idea.

Of all the components in Figure 6, it is the message itself that has traditionally received the most attention. Writers on rhetoric have discussed the elements (such as ethos, pathos, and logos) that make arguments more convincing.


The Message

The existence of strong arguments is well recognized as a requirement of persuasion. Unfortunately, the definition of strong arguments is usually quite tautological. In typical research, several arguments for a position are prepared and shown to a large group of participants. They rate the arguments on a scale that runs from convincing to unconvincing. Aggregate results are tabulated, arguments with mixed results are set aside, and those identified as either strong or weak by consensus are adopted for the experiment and used on other (similar) participants. This empirical process seems to be quite valid, but does nothing to identify or characterize what it is that makes an argument convincing.

Recent studies of the message have looked at the type, sequence, and number of arguments that are most convincing under different circumstances.

Arguments that state an explicit conclusion are more effective than those that state premises and allow the audience to draw their own conclusions (Cope & Richardson, 1972; Feingold & Knapp, 1977). Counter-intuitively, this is true even when the audience consists of well-educated participants who could be expected to have drawn the appropriate conclusion on their own, and to have appreciated the opportunity to do so (Hovland & Mandell, 1952).

Two-side arguments have been found to be more believable than one-sided appeals (Bridgwater, 1982), especially when the audience has some prior knowledge of the topic (Jackson & Allen, 1987). In terms of the order of arguments, it has been observed that two-sided arguments work better in certain sequences. Specifically, refuting counter-arguments before presenting supportive arguments has been shown to be less effective than presenting the supportive arguments first, or interweaving both kinds of arguments together. It has also been noted that it is important to uncover and refute the particular objections that are relevant to receivers (Lavine & Snyder, 2000).

Arguments are traditionally presented in order from the weakest to the strongest. While most studies show very little effect for the order of arguments, those that do show any effect suggest that this sequence is marginally more effective than presenting the strong arguments first or presenting them in a random order (Gilkinson, Paulson, & Sikkink, 1954). However, if there is any chance of being interrupted before finishing the argument (as in an interactive presentation or conversation), it is best to make the strong arguments first.

Whether the earliest arguments made are the most effective (primacy effect) or the last ones (recency effect) seems to depend on the topic, also. Primacy effects are found with interesting or controversial claims and familiar topic areas, while recency effects are found with uninteresting or uncontroversial claims and unfamiliar topic areas (Rosnow, 1966). However, in all of these cases these differences are small.

How much change will receivers accept? Research in this area is not conclusive. Generally there seems to be a curvilinear (inverted-U) relationship. Arguments very similar to the receiver's position may be ignored or create a backlash, while arguments very different from the receiver's position may be rejected out of hand. (Na, 1999). The optimal level of discrepancy that will be accepted by a receiver tends to vary directly with the credibility of the source and inversely with the level of the receiver's involvement in the issue (Levin, Nichols, & Johnson, 2000).

Another important aspect of the message is the degree to which it appeals to emotion. Appeal to emotion is considered a fallacy in philosophical argumentation, because it tends to bypass the critical thinking skills upon which rational analysis is based (Chaffee, 1994). However, in persuasion, appeals to emotion are quite common. Fear appeals in particular have been widely researched. These will be looked at in some detail because, as emotional appeals, they bear a family resemblance to the use of humor in persuasion.

Fear appeals are considered to be effective up to a point. Some reviews (e.g., Boster & Mongeau, 1984) indicate that high-fear appeals create more reported intention to act than mild- fear appeals or no-fear appeals, and may even lead to the actual execution of the intended behavior. It is admitted that such appeals may work partly through cognition (information about future risk) rather than purely through emotion. However, earlier reviews (e.g., Janis, 1967) had suggested that no-fear conditions led to more behavioral change. It would seem that there are contingencies at work here that require further research.

Fear appeals can backfire or boomerang when they lead to paralysis or resistance because they are too intense or transparent (Robberson & Rogers, 1988). Punam Keller (1999) found that lower fear appeals worked better for the unconverted while higher fear appeals were more effective at increasing commitment among people who were already somewhat committed to the advocated point of view.

The success of using fear appeals seems to depend on the subject matter, as well. George Brooker (1981) found fear appeals in toothpaste advertisements created a negative backlash. In trying to persuade people about a resource management issue, rational and emotional appeals were found to have about the same effect (Zinn, 1998)). However, in informing people about domestic terrorism or juvenile crime, Robin Nabi (1998) concluded that discrete negative appeals had a more positive effect than rational appeals.

There are complications in researching fear appeals that may be instructive for humor research. Often the manipulation of a fear appeal adjusts the intensity of the presented danger (from tame to graphic), without assessing participants' response in terms of arousal. This is problematic, because correlations between attempts to frighten people and fear responses are rarely higher than 0.36. Furthermore, under current standards of research ethics, it is not usually permissible to upset a research participant very much in the name of creating knowledge. The analogous situation in humor research is the addition of tendentious (sexual or aggressive) material without assessing whether it is actually more salient to the participants.

Emotional and rational appeals seem to operate quite differently. Emotional appeals tend to generate affective dissonance with the receiver's attitudes. In an attempt to resist this, receivers may deny the relevance of the message information or process it superficially. On the other hand, rational appeals tend to generate cognitive dissonance, which can be reduced through greater critical scrutiny of the arguments (Keller & Block, 1999). This scrutiny leads the receiver into considering the arguments which, if strong, may convince the receiver. In most cases, messages that succeed are matched with the receiver's preference or style on the affective/cognitive dimension (Fabrigar & Petty, 1999).

Messages that refer to personal examples (case histories) are more convincing than those that refer to statistics (Taylor & Thompson, 1982), even when those statistics are obviously considering a wider and more realistic sample of the same sort of events (Koballa, 1986).

Two specialized persuasive strategies have received special attention. The foot in the door technique has been shown to be effective through the activity of dissonance (DeJong, 1979). People who have complied with a small request, without obvious external justification such as payment or duress, will be more likely to comply with a larger request later. There is also a corresponding door in the face effect. Immediately after refusing to comply with a large request, people will sometimes be willing to comply with a smaller one whether to reciprocate for the apparent concession by the source, or because the small request seems smaller in contrast to the large one (Fern, Monroe, & Avila, 1986).

In summary, there are several well-researched factors about the message itself that will predict whether a persuasive appeal is effective. These factors can be considered when predicting whether specific examples of humor will or will not be effective in persuasion.


The Source

Some sources are more persuasive than others, depending primarily on credibility and liking. In turn, each of those dimensions has two main components.


SOURCE CREDIBILITY

Two factors in source credibility have been described as knowledge bias and reporting bias (Eagly, Wood, & Chaiken, 1978). Receivers must believe that the source has the appropriate knowledge (competence) and will report it honestly (trustworthiness).

Looking at the first factor in credibility, speakers are credible to the degree that they are seen as competent (Hennigan, Cook, & Gruder, 1982), a quality that has been demonstrated to affect persuasiveness strongly and directly (Benoit, 1987). A wide variety of factors can influence judgements of source competence, such as the effective use of language (Beatty & Behnke, 1980). Receiver judgements of competence are strongly influenced by information about the training and experience of the source (Swenson, Nash, & Roos, 1984). It is important that audience members know about this competence during their contemplation of the arguments, because it is not as effective if discovered after the fact (Mills & Harvey, 1972).

Looking at the second factor in credibility, sources are credible to the degree that they are seen as trustworthy, in the sense that their intentions are seen as appropriate (Mackie & Worth, 1989). Sources who are seen to have a personal interest in the outcome are less persuasive (Chaiken & Maheswaran, 1994). A statement that is or seems to be counter to the interests of the source (self-effacing) will greatly enhance the trustworthiness of that source. Even low-prestige communicators can gain great credibility in such cases, as demonstrated with criminals arguing in favor of stronger court systems (Walster, Aronson, & Abrahams, 1966).

Another way of explaining the high credibility of self-effacing statements is to refer to attribution theory (Eagly & Chaiken, 1975). When people advocate positions that are against their own interests (or sometimes positions that are strongly against the audience's interests), the audience is certain that speakers are not trying to ingratiate themselves. The audience attributes motives to the speakers, such as being the reluctant bearer of bad news, which increases their credibility and even creates respect for their courage.

An expert, for example, will try to seem wholly unbiased. It is in the expert's self-interest never to be proven wrong, and never to take the wrong position. Thus, taking any position at all will be seen as counter to the expert's interests and any position that an expert advocates will have credibility (Arnold & McCroskey, 1967).

In summary, sources are more credible when seen as competent and trustworthy. Humor may not do much to demonstrate competence, but self-effacing humor can surely convey trustworthiness.


LIKING FOR THE SOURCE

Besides credibility (made up of competence and trustworthiness), the other source variable is liking for the source (made up of similarity and attractiveness).

People are expected to like and trust those who are similar to them in relevant ways, and who hold similar attitudes or a shared perspective (Woodside & Davenport, 1974). Receivers are interested in what these similar sources have to say. However, there is great complexity in the relationship between relevant similarity and persuasiveness, and few predictions can be made without detailed knowledge of the context (Atkinson, Winzelberg, & Holland, 1985). It seems reasonable to assume that a shared sense of humor would count as evidence of a shared perspective.

Besides those who are relevantly similar, people are persuaded by those they find attractive and with whom they identify (Pallak, 1983). After a careful review, Shelly Chaiken (1986) concluded that an unattractive expert's message is accepted only when supported with strong arguments, while an attractive non-expert's message is nearly as effective with or without strong arguments. Furthermore there is more flexibility in using attractiveness for persuasion than in establishing credibility. Learning of an attractive person's view after reading an argument will have a persuasive effect, while the effects of credibility are not achieved unless that credibility was known beforehand. So, if humor improves the attractiveness of the source and/or establishes similarity, it should enhance the effectiveness of persuasion.

However, it is generally agreed that credibility will trump liking. For example, in the very credible case of people who are speaking against their own interests, disliked communicators have been shown to be just as persuasive as liked communicators (Maddux & Rogers, 1980). Furthermore, having secured compliance with counter-attitudinal behavior, a disliked communicator will actually create more dissonance and therefore produce more attitude change (Zimbardo, Weisenberg, Firestone, & Levy, 1965). It seems that credibility is more important to the effectiveness of persuasion than liking for the source.


The Receiver

The elaboration likelihood model of Richard Petty and John Cacioppo (1986) has recently been summarized by one of the authors as a theory about the processes underlying changes in the judgments of objects, the variables that induce these processes, and the strength of the judgments resulting from these processes (Petty & Wegener, 1999). It starts from the proposition that people do not respond to persuasive arguments in a robot-like fashion. Instead they either do or do not persuade themselves in the face of arguments that they find convincing.

When an issue is important to them, people will carefully weigh the arguments (elaborate on them) and make their decision on that basis. However, when they are unable or unmotivated to do that, people will decide on the basis of peripheral cues such as their feelings toward the source (Schwarz, Bless, & Bohner, 1991) or their own general knowledge structures (Hughes, 1998).

The first approach is called the central route and the second is called the peripheral route to persuasion. Shelly Chaiken (1980) made the same distinction at around the same time, but referred to the use of message cues as systematic processing and source cues as heuristic processing. Recently some writers (e.g., Kruglanski & Thompson, 1999) have argued that there are not really two separate routes to persuasion but rather a variety of routes along a continuum. However, this observation is clearly made in Petty and Cacioppo's original article on the topic.

According to the elaboration likelihood model, whether receivers use the central route (consider the arguments carefully) or rely on heuristic criteria (such as qualities of the source) depends primarily on two factors. The first is involvement; defined as the relevance, subjective importance, or commitment the receiver feels toward the topic. In research this has usually been operationalized by giving students articles about either a proposed new academic hurdle that will apply to them or one that will apply only to future generations of students. For participants with high involvement in a topic, source credibility in any form is less important than argument strength. If participants are committed to an idea, whether by prior actions or public statements or by having chosen the position freely, they will be significantly more difficult to persuade through any means other than the arguments themselves.

The other element that enters into the decision to use the central or peripheral route is need for cognition. For some people, such as university professors, there is a propensity to process events cognitively. These people will be somewhat more likely to use the central route regardless of their level of involvement (Petty & Cacioppo, 1986). Recent experimentation confirms this effect (Shestowsky, Wegener, & Fabrigar, 1998).

Although the elaboration likelihood model suggests that the preferred mode of processing (central or peripheral) is determined by involvement and need for cognition, Wolfgang Stroebe (1999) expresses a similar idea in a very different way. In his view, peripheral processing is the natural or default mode, which will always be used by everyone unless the receiver is highly involved or has a particularly high need for cognition.

Recent research by Bless and Schwarz (1999) makes a similar point. Results suggest that participants in a good mood prefer heuristic processing regardless of their motivation or preference for elaboration. Speculating, perhaps central processing is an awkward and unnatural activity that is undertaken only after an intentional education in critical thinking skills.

The effect of humor is likely to be found only among those who are interested in the peripheral route, for whatever reason.

Besides the elaboration method, receivers differ in personality generally. High authoritarians, for example, perceived a threat as stronger in argument quality than a reward message. Low authoritarians perceived the reward message as stronger in argument quality than the threat message (Lavine et al., 1999). The relationship of other receiver characteristics and susceptibility have been investigated, particularly self-esteem and intelligence levels, but with contradictory results (Romer, 1981; Skolnick & Heslin, 1971). Strong personality traits can have many effects: While they strengthen the receiver's confidence and open-mindedness and ability to understand a convincing argument, they also support the ability to perceive flaws in a weak one and the strength to resist it (McGuire, 1985).

Receivers also have less-enduring characteristics such as their mood. The research in this area generally suggests that positive affect reduces resistance to persuasion (Bless, Bohner, Schwarz, & Strack, 1990; Bohner et al., 1992; Hughes, 1998; Keating & Kuykendall, 1990; Petty et al., 1993; Sinclair, Mark, & Clore, 1994). To the degree that humor creates a light mood, it would be expected to support persuasion.


The Situation

Some aspects of the situation or context in which persuasion is attempted can affect whether it is successful or not.

When the situation forewarns receivers that an attempt at persuasion will be made, receivers appear to prepare in advance and construct more counter-arguments during the communication. As a result, they are less susceptible to persuasion, especially for high involvement topics (Petty & Cacioppo, 1979). When the warning also tells them which position will be advocated, receivers are able to pre-rehearse counter-arguments and become extremely resistant to persuasion (Freedman & Sears, 1965). Similarly, receivers with prior knowledge of a topic tend to be more difficult to persuade than those without such knowledge (Apsler & Sears, 1979).

However, these effects can be counteracted by intentionally distracting the participants (Romero, Agnew, & Insko, 1996). For example, Festinger and Maccoby (1964) found that students were more persuaded when distracted with an irrelevant (zany) film than when focused on a film of the speaker. Osterhouse and Brock (1970) attributed this effect to the ability of the distraction to block the formation of sub-vocal counter-arguments. If a humorous communication is distracting, it may create this effect.

The medium of communication has also been studied. It is difficult to separate the effects of different media (magazine, radio, television) from the inherent differences in the messages that they carry. In terms of the effective communication of the message itself, radio has been found to be more effective than written arguments. The addition of voice inflection improves the ability to convey and understand a message. Television was found to be even more effective, with the addition of visual cues (Chaiken & Eagly, 1983).

In general, the richer the medium, the more clear the communication is. However, this seems to have no effect on the persuasive effects of arguments. In fact, complex messages are sometimes more effective in written form than on audio or video tape (Chaiken & Eagly, 1976). Presumably this is because readers can go back and re-read troublesome passages, which they cannot do during radio and/or television broadcasts.


Link with Behavior

Attitudes will impact behaviors more strongly when they are seen as relevant to the behavioral decision, and when they have been formed under personally engaging circumstances. For persuaders to move their receivers beyond attitude change to behavior change, they need to convince people that attitude/behavior consistency is desirable. People do not seem to generally expect consistency between their attitudes and behavior unless educated to do so (Fazio & Zanna, 1981; Regan & Fazio, 1977; Smith & Swinyard, 1983).

For example, participants in an experiment who were not reminded that their decision was relevant to a larger issue (affirmative action) showed only a 0.08 correlation between their prior attitudes and their final decision. Those who were reminded of the connection showed a 0.51 correlation between their prior attitudes and their decision (Snyder & Kendzierski, 1982).

Whether attitudes will lead to behavior change also depends on the salience of the original attitude changing experience (Fazio & Zanna, 1981). This may explain why one dramatically presented case example is often more effective at changing behavior than a rigorous set of statistical results. For example, Smith and Swinyard (1983) found a 0.57 correlation between product purchase and attitude when the attitude was formed through a direct product trial but only a 0.18 correlation between product purchase and attitude when the attitude (whichever direction) was formed through advertising claims. When humor successfully creates a charged atmosphere, attitudes that are formed in that atmosphere may be more likely to be reflected in behavior.




HUMOR AND PERSUASION


Humor is widely thought to be an effective tool for persuasion. Media experts insist that it is effective in advertising (e.g., Heinecke, 1997). Teachers insist that it is effective in education (e.g., Droz & Ellis, 1996). Humor is believed to improve learning (Ziv, 1988), arouse student interest (Bergin, 1999), illustrate concepts (Powell & Andresen, 1985), build rapport with teachers (Pollack & Freda, 1997), and increase motivation through immediacy (Jaasma & Koper, 1999). Humorous messages seem to be more effective than mild fear appeals (Brooker, 1981) and humor is listed by some as the number one psychological motivator (Severn, 1988). Oddly, humor has been shown to work better with a weak argument, for which it tends to compensate, than with a strong argument, from which it tends to distract (Cline & Kellaris, 1999).

However, some of the research in this area suffers from methodological problems such as comparing student-perceived teacher humor with student-perceived learning (Wanzer & Frymier, 1999), teacher-perceived use of humor by principals with teacher-perceived burnout (Spurgeon, 1998), or simply gathering and publishing opinion surveys (Prosser Jr., 1997).

Careful research is rarely able to demonstrate the presumed effects (e.g., Bryant, Comisky, Crane, & Zillmann, 1980; Clinton Jr., 1995). Humor draws attention primarily to itself (Rieck, 1997). It may offend some listeners (Sev'er & Ungar, 1997) and can actually reduce retention (Fisher, 1997). Some humor, such as exaggeration and irony, may be retained literally by students and distort learning (Weaver, Zillmann, & Bryant, 1988). Research suggests that teachers may like to use humor because it increases their own popularity (Steele, 1998), and advertising firms may like to use it because it increases the likelihood of winning an industry award (Gagnard & Morris, 1988).

Dorothy Markiewicz's (1974) authoritative review concluded that humor had little effect on retention, comprehension, persuasion or even source evaluation and these assertions have recently been validated (Michaels, 1997). Humorous advertisements can entertain audiences without generating recall, retention, or sales results (Cantor & Venus, 1980; Duncan, 1979). Using content analysis on business to business advertisements, Naccarato and Neuendorf (1998) could find no effect for humor on aided recall, readership, or ratings of print ads as either informative or attractive.

On the other hand, humor may have a more subtle and long-term effect. One study found that long-term retention was better for material learned with humor, even when there were no significant differences for humor in short-term recall (Kaplan & Pascoe, 1977). Another found that attitude toward the ad and the brand improved over time when humor had been incorporated in the advertisement (Lee & Mason, 1999). In one experiment involving a lesson about finding ticks, the humorous training did not provide better learning than the non-humorous training, but the students in the humorous condition later became significantly more worried about ticks (Snetsinger & Grabowski, 1994).

Humor can serve another function. After convincing people of an argument, it is sometimes desirable to try and innoculate them against inevitable counter-arguments. One way to do this is to present weak counter-arguments and refute them to demonstrate how easily this can be done (Pryor & Steinfatt, 1978). Bringing up (and refuting) humorous counter-arguments can sometimes serve this function.

The effectiveness of humor in persuasion (especially in the case of advertising) has been modeled in two ways; cognitive and affective. The cognitive model indicates that humor positively influences processing of a persuasive message by provoking attention, which engages an audience and motivates them to move through an information-processing hierarchy (Gelb & Zinkhan, 1986).

There has been a growing interest, however, in the impact of affect and emotion in persuasion as researchers increasingly recognize inadequacies of information-processing models. The affective model for humor in persuasion suggests that a favorable attitude toward the advertisement is a mediating variable which positively influences attitude toward the brand, purchase decision, and other outcomes of interest to advertisers. Research suggests that a conditioning process takes place, and positive attitude toward the ad is generalized onto the product itself (Holbrook & Hirschmann, 1982).

A recent careful review of the advertising literature updated Markiewicz's work and suggested that humor attracts attention, does not harm comprehension, does not appear to offer an advantage over non-humor at increasing persuasion, does not enhance source credibility but does enhance liking for the source, and is most effective if related to the message rather then unrelated (Weinberger & Gulas, 1992).


Comparative Analysis

There are interesting parallels between persuasion and humor. Persuasion involves a source offering a new message to a receiver; humor involves an initiator pointing out a funny object to an appreciator. Persuasion depends on internal processing by a receiver, who does or does not find the message convincing; humor depends on internal processing by an appreciator, who does or does not find the object funny. The goal of persuasion is to change the attitude (mental state) of receivers, and preferably change their behavior as a result; the goal of humor to change the affective (emotional) state of an appreciator, and preferably generate laughter (a behavior) as a result.

However, there are also interesting differences between persuasion and humor. If persuasion is achieved without a source, it is called learning and not persuasion. If humor is achieved without an initiator, it is still humor. Persuasion is ethical to the degree that the receiver is free to reject the message. Humor is ethical to the degree that the object of the humor consents to it.

Comparing the theories themselves, persuasion theory is much more developed. At the end of the second world war, after victory had been achieved in Europe, the United States military was anxious to keep its forces motivated. Carl Hovland, Irving Janus and others were heavily funded to conduct research in persuasion and this work continued long after the war. After several decades of research by social psychologists and communication experts, constructs such as involvement and need for cognition have been well defined and the relationships among them carefully researched.

Humor theory has never been well funded. Constructs are not well defined and research into their relationships is sparse. The phenomenon has been investigated through the disjointed effort of philosophers, psychologists, anthropologists and scholars of literature and linguistics. This work has not been well co-ordinated until the recent appearance of the International Society for Humor Studies in 1988.


Integrating the Theories

Source factors, such as credibility, are relevant when involvement is low and there is foreknowledge of an attempt to persuade. In the case of advertising, and in most cases of training, there is foreknowledge of the attempt to persuade. Looking at persuasive attempts in advertising, Yong Zhang (1994) found that humor was most effective in low involvement situations. This is consistent with the argument that it operates through the peripheral route.

Credibility is comprised of competence and trustworthiness. Although the effects of humor on perceived competence can be negative (Kushner, 1988), there is a positive role for humor in enhancing the sense of trustworthiness. One of the most effective ways to demonstrate trustworthiness is to speak against one's own interests (Wood & Eagly, 1981) and self-effacing humor does just that. When sources are willing to take themselves lightly they will be less likely to be seen as Machiavellian influencers with dark motives.

Liking for the source is an important variable that is second only to credibility in effectiveness. Liking is comprised of similarity to the receiver and attractiveness of the source. Sources are most effective when they are similar to the receivers in terms of attitude, not position. A shared sense of humor is a strong indicator of people with similar attitudes (Lundy, Tan, & Cunningham, 1998) and has been associated with intimacy (Olson, 1996). Furthermore, any sense of humor at all has been shown to be attractive to those seeking life companions (Cann, Calhoun, & Banks, 1997) and is therefore expected to generate referent power. The effectiveness of humor in persuasion operates at least partially through its ability to increase liking for the source.

Although the literature has not yet supported the conclusion that humor (in general) supports persuasion (in general), there is reason to think that humor may bolster the weak link between attitude change and behavior. The relationship between attitude and behavior is strengthened when that attitude has been formed under engaging or salient conditions (Regan & Fazio, 1977). There is evidence to suggest that the use of humor increases arousal and personally engages audiences (e.g., Madden & Weinberger, 1982). Audiences thus stimulated can be expected to exhibit a higher correlation between their attitudes and behaviors (or behavioral intentions at least).

Historical research suggested that humor aids recall. Heim (1936) found that after a delay of two to twenty-four weeks 62% of material initially laughed at was remembered as compared to 8% of other material. Items that were recalled had an average funniness score of 2.1 (0=not funny to 4=very funny) while those that had been forgotten had an average score 1.3, as calculated later by Peter Derks and his associates (Derks, Gardner, & Agarwal, 1998). For students with SAT scores over 1200, Sagaria and Derks (1985) found that non-humorous phrases were less remembered than humorous captions or cartoons without any captions. Thus bright students seem to remember material better when it has been softened with humor.

However, research often shows no significant effect for humor in advertising (e.g., Duncan & Nelson, 1985) or in education (Gruner & Freshley, 1979). Humor's effect seems to depend on (and perhaps be attributable to) two factors. First, the humor must be closely related to the topic or message. In fact, simple repetition of the message works almost as well as using humor to re-iterate the message (Desberg, 1981). Second, the humor must be arousing or tendentious in order to create the engaging learning conditions discussed above. In fact, any arousing material may work just as well as tendentious humor (Derks et al., 1998). Thus humor may operate by providing qualities for the persuasive message that can be had without the use of humor.

Previous studies in the area of humor and persuasion often lacked theoretical bases, instead gathering empirical evidence and generalizing from that. This brief review of persuasion and humor theories has created some interesting insights and afforded an opportunity to generate the following propositions about when humor will and will not support persuasion.




PROPOSITIONS


The first proposition has to do with the use of humor in general. Persuasion theory suggests that participants who are in a good mood feel positive toward everything (Sinclair et al., 1994) and therefore less likely to disagree with a persuasive message (Eagly, Chaiken, & Wood, 1982). For example, some authors assert that students relax and are better able to absorb material when a teacher uses humor (Yura-Petro, 1991). Those who were served refreshments during an experiment were more amenable to persuasion (Janis, Kaye, & Kirschner, 1965). Those who were given a cookie during a questionnaire rated the survey higher (Brief, Butcher, & Roberson, 1995). Guitar music made receivers more susceptible to persuasion (Galizio & Hendrick, 1972). Positive affect has been linked to increased use of heuristic processing (Bless & Schwarz, 1999) and reduced resistance to persuasion (Mackie & Worth, 1989).

Specifically, humor that is enjoyed by the receiver has been directly linked to generating the sort of positive affect that increases susceptibility to persuasion (Moran, 1996). Sven Svebak and Michael Apter (1987) confirmed that humor changes participants' state from telic (serious- minded) to paratelic (playful). Indeed, negative affect is incompatible with the appreciation of humor. For example, participants were given a mindless task with or without an explanation. Those with an explanation laughed along with an accidental burp on the instruction tape, while those who were annoyed to be working without explanation did not laugh (Raven & Rietsema, 1957). The enjoyment of humor both requires and reinforces positive affect. Thus any use of humor at all is expected to improve the effectiveness of persuasive communication.
P1 - Persuasive messages with any sort of enjoyed humor will be more effective than those without any humor.
It turns out that cartoon drawings may be an effective medium for mood enhancement. Careful empirical analysis has often found that humor in general (in textbooks, for example) is related to enjoyment but not persuasiveness (Klein, Bryant, & Zillmann, 1982) or has no significant effect (Satterfield, 1988). However, cartoon drawings in particular have been shown to generate positive affect and suggest a more relaxed and varied learning environment (Carpenter, 1997). They have even been linked to slight but significant increases in persuasiveness (Bryant, Brown, Silberberg, & Elliott, 1981).

Persuasive appeals should be matched with the receiver's style and interests. This match of styles leads the receiver to conclude that the source is similar in relevant ways. Cartoons have been shown to match the style and interests of students (Burns, 1999; Townsend, 1983). Thus cartoon drawings in particular are expected to support persuasion.
P2 - Persuasive messages with cartoon drawings will be more effective than those without them.
There are several reasons to expect that the use of irony will support persuasion. Humor theory suggests that humor attracts attention (Chapman & Crompton, 1978; Duncan & Nelson, 1985), especially when that humor is relevant to the message (Spotts, Weinberger, & Parsons, 1997), and also that it encourages further processing of the message (Schmidt, 1994). Persuasion theory suggests that, if participants attend to a distraction, they may be discouraged from creating and rehearsing counter-arguments (Osterhouse & Brock, 1970) and become more susceptible to persuasion. This was reaffirmed recently when participants who were distracted by being required to remember a seven-digit number were more persuaded by emotional appeals than those who were only required to remember a two-digit number (Shiv & Fedorikhin, 1999).

The distraction of irony is also thought to counteract participants' resistance to an attempt at persuasion of which they have been forewarned (Romero et al., 1996). In a recent experiment (Derks et al., 1998), tendentious humor such as irony had a positive effect on motivation and strength of recall. Irony earns attention by arousing audiences with its contradictory levels of meaning (Herzog & Larwin, 1988). The processing of irony is particularly distracting because both the literal and the ironic meanings must be decoded successfully (Giora & Fein, 1999; Grice, 1975; Searle, 1979).

Today, people are comfortable with wisecracks; using them to break the ice, fill awkward silences, smooth the way for requests, and build group solidarity (Norrick, 1993) and to demonstrate their mastery and power (Christianson, 1989). It is expected that the processing of ironic wisecracks will distract participants sufficiently to make them more amenable to persuasion.
P3 - Persuasive messages with ironic wisecracks will be more effective than those without them.
Persuasion theory suggests that a source is considered more credible when lacking self-interested motives (Eagly & Chaiken, 1975) or speaking against its own self-interest (Walster et al., 1966). Self-effacing humor, which seems to speak against the interests of the source, creates a conspiracy between the speaker and listener that favors credibility and adhesion (Koren, 1992).

The use of self-effacing humor has already been shown to improve source credibility (Hampes, 1999), which is strongly associated with persuasiveness (Stoltenberg & McNeill, 1984). Self-effacing humor has been shown to be more appealing (Chang & Gruner, 1981; Tamborini & Zillmann, 1981) and experts like Charles Gruner suggest that humor can work only when it is presented as self-effacing (Zemke, 1991).
P4 - Persuasive messages with self-effacing humor will be more effective than those without that context for the humor.
Many studies have followed the development of sense of humor in children from smiling to laughing to understanding irony (Bernstein, 1986; Brodzinsky, 1977; Heckel & Kvetensky, 1972; McGhee & Lloyd, 1982; Shultz & Horibe, 1974). Few studies have been done on the development of the sense of humor past the age of adolescence. One of the few discussions in this area (McGhee, Ruch, & Hehl, 1990) suggests that the personality factors of conservatism, sensation-seeking, and openness to experience are the more relevant than age for assessing individual differences in adults.
P5 - Age will not moderate the effectiveness of humor in persuasion.
Research in gender has produced mixed results. Traditionally authors have found that men liked sexual and aggressive humor more than women (e.g., Ziv, 1984). Recently researcher has suggested that all people prefer humor at the expense of the opposite sex (Jackson & Jackson, 1997). Some report that there are few differences between the genders (Henkin & Fish, 1986), while others contend that the instruments used in humor research is biased toward angry male humor (Caliskan, 1995). A recent thorough review concludes that Men might be more likely to make witty wisecracking remarks, yet women may be just as likely to tell funny personal stories (Lampert & Ervin-Tripp, 1998). In fact, high-ranking business women (in Israel, at least) have been shown to use humor as often as men (Ehrenberg, 1995).

However, it is expected that women will score lower on the Humor Initiation Scale (Cox, Read, & Van-Auken, 1990) and show less preference for hostile humor (Mundorf, Bhatia, Zillmann, Lester, & Robertson, 1988), such as that found in Dogbert wisecracks (Johnson, 1997). In this experiment it was expected that men would enjoy and be persuaded more by the use of such humor than women.
P6 - Gender will moderate the effectiveness of humor in persuasion such that male participants will be more persuaded.
Receivers with high involvement in an issue were expected to utilize the central route to persuasion, seeking arguments upon which to elaborate (Petty & Cacioppo, 1984). They were expected to rely less on heuristic factors such as source characteristics, and therefore to be less affected by peripheral cues such as humor (Levin et al., 2000). It was assumed that those with more work experience would feel more involvement with the issues presented in reality-based cases (Andersson, 1996). Accordingly, it was thought that they would seek logical arguments and be less persuaded by peripheral factors such as humor.
P7 - Experience will moderate the effectiveness of humor in persuasion such that those with more experience will be less persuaded.
Herring (1994) points out that the clown motif has been a part of all cultures. Contrary to the popular notion that humor translates poorly from one culture to another (e.g., Draitser, 1998), such problems are often due to language (Tamaoka & Takahashi, 1994). If language issues are avoided, as in visual humor, it translates surprisingly well. No national differences were found on path analyses of 44 Finnish and 68 American university students watching ten humorous television commercials (Unger, 1995) and the same researcher earlier reported finding two factors (aggression and nonsense) in the humor tests of both groups (McCullough, 1993). Willibald Ruch, arguably the best scholar in the psychology of humor, found that French and German people appreciated the same types of humor to the same degree, except that they differed culturally in their response to sexual humor (Ruch, Ott, Accoce, & Bariaud, 1991).
P8 - Cultural diversity will not moderate the effectiveness of humor in persuasion.
Thomas Cline (1997) has suggested that the effectiveness of humor may vary with an individual's need for levity. While no established instrument exists for this variable, there are several established measures of the sense of humor (Ruch, 1996) that have been used to predict humor's effectiveness (Dixon, Willingham, Strano, & Chandler, 1989). The need for levity can be operationalized by combining such tests as long as humor creation, appreciation, and exploitation are all measured. It was expected that those with higher scores on this dimension would appreciate the humor better, and be more persuaded by it.
P9 - Sense of humor will moderate the effectiveness of humor in persuasion such that those with a stronger sense of humor will be more persuaded.
In order to be effective, sources must match their persuasive messages to the style and preferences of their audience (Dibble, 1999; Fabrigar & Petty, 1999; Lavine & Snyder, 2000). In the case of humor, once that match has been achieved, participants will enjoy the specific humor and relate to it. Not only will it strike them as funny, but it will also convince them that the source is similar to them in relevant ways (Wolosin, 1975) and can be trusted (Cann et al., 1997). Thus they will be more receptive to the persuasive message (Mackie & Worth, 1989).
P10 - Preference for the specific humor used will moderate the effectiveness of humor in persuasion such that those who prefer the humor will be more persuaded.
Few people want to admit having no sense of humor. In a classic study, less than 1% rated their sense of humor as below average (Omwake, 1937). Accordingly, there is reason to worry that people will over-state their sense of humor. Such tendencies can be assessed indirectly with a Social Desirability Scale. Those who score high on the scale may be willing to distort the truth in order to give people the answers they want to hear, and there is reason to suspect that they may also be inflating their self-reported sense of humor. Furthermore, those who conform so easily are less likely to think independently (Avtgis, 1998), which may impede their sense of humor. Thus it is thought that those who score highly on a social desirability scale may miss many of the effects of humor.
P11 - Tendency to provide socially desirable responses will moderate the effectiveness of humor in persuasion such that those who exhibit a stronger tendency will be less persuaded by it.



© 2001, James Bruce Lyttle