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Social and Personality Psychology Compass 4/9 (2010): 783–794, 10.1111/j.1751-9004.2010.00292.x
Metaphor and Persuasive Communication:
A Multifunctional Approach
Victor C. Ottati* and Randall A. Renstrom
Loyola University Chicago
Abstract
Metaphors are pervasive in both mass communication and interpersonal exchanges and can play
an important role in persuasion. Metaphor serves multiple functions in persuasive communication,
and the effect of metaphor on persuasion is potentially mediated by multiple psychological process
mechanisms. Nevertheless, we propose that past and future research in this area can be organized
or grouped into three simple categories. First, metaphorical statements can activate information
that is directly applied to the communication topic and thereby influence attitudes toward the
communication topic. Second, metaphorical language may influence impressions of the communication source and thereby impact attitudes toward the communication topic. Third, metaphors
may affect attitudes toward the communication topic by influencing the direction or amount of
elaboration that takes place when recipients process literal statements contained in the communication. A review of past research is organized into these three categories, and proposals for future
research in each category are introduced. It is concluded that future research within each of these
domains should focus on two related questions: under what conditions does metaphor elicit a
given psychological process in the receiver (e.g., attribute mapping, valence transfer), and under
what conditions will a given process result in an increase versus decrease in persuasion?
Metaphor is pervasive in both mass communication and personal linguistic exchanges
(Gibbs, 1994; Lakoff, 1987; Lakoff & Johnson, 1980). Poets tell us that love is a ‘light,’ a
‘fire,’ or form of ‘energy’. Politicians have sought to ‘build a bridge to the 21st century,’
‘ignite a thousand points of light,’ or provide ‘tax relief’. Metaphors can furnish vivid
images, convey multiple meanings in a concise fashion, or express that which cannot be
stated in literal terms (Gibbs & Bogdonovich, 1999; Graesser, Mio, & Millis, 1989;
Ortony, 1975; Paivio, 1979). Some theorists have even argued that all higher-order cognitive functioning is metaphorical in nature (e.g., Lakoff, 1987; Lakoff & Johnson, 1980).
Metaphorical statements often pertain to an attitude object (e.g., ‘Pollution is a cancer,’
‘Elvis is king’), and as such, may play an important role in persuasive communications.
A metaphor contains a topic and a vehicle (Ortony, 1975; Richards, 1936). The topic
is the object or phenomenon being described, whereas the vehicle is some other object
or phenomenon that conveys a certain meaning about the topic. For example, ‘Juliet is
the sun’ contains ‘Juliet’ as the topic and ‘sun’ as the vehicle. Models of metaphor comprehension often assume the comprehension process entails mapping semantic or evaluative implications of the vehicle onto the topic (e.g., Gentner, 1983; Gibbs, 1992; see
Ortony, Reynolds, & Arter, 1978 for a review). Thus, ‘Juliet is the sun’ might convey
that Juliet is a source of energy, warmth, and happiness, or that Juliet simply possesses a
positive valence. Alternatively, ‘television is an addiction’ might convey that watching
television is unhealthy, habit forming, and difficult to stop, or simply that watching television is undesirable (cf. Bowdle & Gentner, 2005; Chiappe & Kennedy, 2001; Gentner
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784 Metaphor and Persuasive Communication
& Clements, 1988; Gibbs & Gerrig, 1989; Glucksberg & Keysar, 1990; Kintsch, 2001;
Ortony, 1979; Ortony, Vondruska, Foss, & Jones, 1985).
Work regarding metaphor and persuasive communication includes purely theoretical
writings, nonexperimental studies, and experimental research (Mio, 1997). Empirical studies regarding the psychological mediators of metaphor effects on persuasion is growing
into a substantial body of literature (e.g., Bowers & Osborn, 1966; Frey & Eagly, 1993;
Graesser et al., 1989; Hitchon, 1997; Johnson & Taylor, 1981; Landau, Sullivan, &
Greenberg, 2009; Mio, 1996; Ottati, Rhoads, & Graesser, 1999; Read, Cesa, Jones, &
Collins, 1990; Sopory & Dillard, 2002). Much of this research has been performed by
scholars outside of social psychology (e.g., communication, cognitive psychology). As a
consequence, this literature has yet to fully incorporate the implications of mainstream
social psychological models of persuasion (e.g., the Elaboration Likelihood and HeuristicSystematic Models). One objective of this study is to more fully incorporate the implications of these models when considering research on metaphor and persuasion.
An additional objective of this study is to provide a conceptualization of metaphor
effects on persuasion that is both comprehensive and simple. Past research has often
focused on very specific effects of metaphor on persuasion, and reviews of the literature
have considered a large list of specific hypotheses, predictions, and findings (e.g., Sopory
& Dillard, 2002). What is needed, however, is a coherent overarching conceptual framework for organizing this expanding number of hypotheses, predictions, and findings.
Social psychological approaches to persuasion have traditionally emphasized relatively simple taxonomies that subsume a vast array of effects (e.g., ‘Who says what to whom?’).
This study takes an analogous approach when considering past and future research regarding the effects of metaphor on persuasion. We assume that metaphor serves multiple
functions in persuasive communication, and that the effect of metaphor on attitudes
toward the communication topic is complex and mediated by multiple psychological process mechanisms. Nevertheless, we believe it is possible to organize or group this work
into three general categories (see Figure 1).
First, metaphorical statements might influence the recipient’s impression of the communication topic in a relatively direct manner. When this is the case, the effect of metaphor on attitude toward the communication topic is independent of other cues (e.g.,
source credibility, argument strength). Second, the effect of metaphor on attitude toward
the communication topic might be mediated by the message recipient’s impression of the
communication source. Lastly, the effect of metaphor on attitude toward the communica-
Figure 1 Three pathways by which metaphor can influence attitudes toward a communication topic.
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Social and Personality Psychology Compass 4/9 (2010): 783–794, 10.1111/j.1751-9004.2010.00292.x
Social and Personality Psychology Compass ª 2010 Blackwell Publishing Ltd
Metaphor and Persuasive Communication
785
tion topic might be mediated by the manner in which the message recipient processes literal statements contained in the communication. We consider several psychological process mechanisms within each of these three categories. In doing so, we do not exclusively
focus on effects of metaphor that are distinct or unique from the effects of literal language. To the contrary, we believe that a comprehensive conceptualization of metaphor
and persuasion should not only consider effects that are unique to metaphor (e.g., comprehension of a novel metaphor elicits an ‘ah ha!’ experience) but also effects that are
similar to those obtained using more literal forms of communication (e.g., metaphor facilitates organization).
Metaphor and Persuasion
A meta-analysis has revealed that metaphor generally increases persuasion (Sopory &
Dillard, 2002). However, the magnitude and direction of this effect vary considerably
across moderating conditions. Metaphor is most likely to increase persuasion when it
identifies a novel comparison, appears at the onset of related arguments, or is semantically
congruent with other metaphorical statements contained in the communication (Read
et al., 1990; Sopory, 2006; Sopory & Dillard, 2002). Some research suggests that metaphor is most effective when the message recipient is familiar with the communication
topic or knowledgeable in the topic domain (Johnson & Taylor, 1981; Sopory & Dillard,
2002; Roehm & Sternthal, 2001; but see Bosman & Hagendoorn, 1991). On the other
hand, other research indicates metaphor can reduce persuasion (Bosman & Hagendoorn,
1991), especially when the metaphor fails to afford clear semantic linkages with literal
arguments contained in the communication (Krumdick, Ottati, & Deiger, 2004). To
better understand this conflicting pattern of findings, it is useful to organize our discussion
in terms of the three aforementioned categories. These are (1) direct effects of metaphor
on attitudes toward the communication topic, (2) metaphor effects that are mediated
by impressions of the communication source, and (3) metaphor effects that are
mediated by manner in which the receiver processes literal statements contained in the
communication.
Relatively direct effects of metaphor on attitude toward the communication topic
As noted previously, many researchers have suggested that metaphor comprehension
entails mapping semantic or evaluative implications of the vehicle onto the topic. Thus,
for example, ‘Professor Williams is a Nazi’ might lead the message recipient to infer Professor Williams is domineering, cruel, racist, or simply unpleasant. As a consequence, the
message recipient might be persuaded to adopt a negative attitude toward Professor Williams. Consistent with this conceptualization, metaphors can elicit an assimilation effect
wherein evaluation of the topic is assimilated toward evaluation of the vehicle (Johnson
& Taylor, 1981; Mio, 1993; Mio, Thompson, & Givens, 1993). This effect is relatively
direct because it is not mediated by the recipient’s impression of the source or the way in
which the recipient processes other literal arguments contained in the communication.
Interestingly, this assimilation effect can emerge even when a metaphor is indirectly
implied, but not explicitly stated in the communication (see Landau et al., 2009).
Assimilation effects of this nature are potentially mediated by two psychological process
mechanisms. First, the metaphor might activate specific semantic attributes that are
mapped on to (or highlighted in) the topic (Edelman, 1971; Hitchon, 1997). In this case,
the metaphor serves as a concise expression that conveys a set of arguments (e.g., ‘Professor
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Social and Personality Psychology Compass 4/9 (2010): 783–794, 10.1111/j.1751-9004.2010.00292.x
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786 Metaphor and Persuasive Communication
Williams is domineering,’ ‘Professor Williams is cruel,’ ‘Professor Williams is racist’) that
elicit persuasion in the direction advocated. Of course, only attributes potentially shared
by the vehicle and topic are mapped on to (or highlighted in) the topic (Hitchon, 1997;
Kintsch, 2001; Newsome & Glucksberg, 2002). For example, the metaphor ‘Professor
Williams is pig’ does not lead the receiver to infer ‘Professor Williams has four legs’.
Thus, evaluation of the topic is specifically assimilated toward evaluation of the shared
features. A second possibility is that the overall valence of the vehicle is mapped on to
the topic. In this case, the metaphor simply functions as an evaluative judgment (e.g., ‘Professor Williams is undesirable’) that produces persuasion in the direction advocated. If this
occurs, evaluation of the topic should be assimilated toward global evaluation of the vehicle. In fact, research indicates that evaluation of the topic is assimilated toward evaluation
of features potentially shared by the vehicle and topic, even when this evaluation is the
opposite of the global vehicle evaluation (Hitchon, 1997). Thus, the attribute-mapping
model has garnered more support than the global valence-transfer model.
Future research should explore conditions that potentially moderate effects of this nature. For example, it is possible that the attribute-mapping model (i.e., metaphor functions
as a set of arguments) is supported under high elaboration likelihood conditions (e.g.,
high personal relevance) whereas the valence-transfer model is supported under low elaboration likelihood conditions (e.g., low personal relevance). From this perspective, attribute-mapping constitutes a form of central processing whereas valence-transfer constitutes
a more peripheral form of persuasion (see Petty & Cacioppo, 1986, for a multiple role
analysis of persuasion cues).
Indirect effects mediated by the recipient’s impression of the communication source
Many researchers have suggested that metaphor elicits positive impressions of the communication source which increase persuasion in the direction advocated (Bowers &
Osborn, 1966; McCroskey & Combs, 1969; McGuire, 2000; Reinsch, 1971, 1974). This
connects metaphor and persuasion research to a vast literature that documents the role of
source credibility and source attractiveness in persuasion. Message recipients may simply
regard metaphor as a sign of genius or brilliance (Sopory & Dillard, 2002). Alternatively,
metaphor might elicit a favorable impression of the source when it enlightens the listener
by identifying similarities between the vehicle and topic that have not been previously
considered. Research that demonstrates novel metaphors are more persuasive than conventional or ‘dead’ metaphors is compatible with this later possibility (Sopory & Dillard,
2002). In the former case, metaphorical language functions as a simple, heuristic cue that
signals the source is highly intelligent and credible. Presumably, this is most likely to
occur when elaboration likelihood is low. In the latter case, the message recipient must
analyze and appreciate the ingenuity of the metaphorical statement before deriving a positive impression of the source. This should occur when elaboration likelihood is high (for
a related discussion see Petty & Cacioppo, 1986).
A review of the literature, however, does not support the blanket assumption that metaphor increases persuasion because it enhances source credibility. In some cases metaphor
increases perceptions of source credibility (Bowers & Osborn, 1966). However, in other
cases metaphor fails to influence or even decreases perceptions of source credibility (Bowers & Osborn, 1966; McCroskey & Combs, 1969; Reinsch, 1971; see Sopory & Dillard,
2002 for null effects in a meta-analysis). Metaphor is associated with an increase in source
attractiveness (Read et al., 1990; Mio, Riggio, Levin, & Reese, 2005; see Sopory &
Dillard, 2002 for a meta-analysis). Nevertheless, research has failed to document that the
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Social and Personality Psychology Compass 4/9 (2010): 783–794, 10.1111/j.1751-9004.2010.00292.x
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Metaphor and Persuasive Communication
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effect of metaphor on persuasion is mediated by source impressions. In some studies, metaphor influences attitudes toward the communication topic, but fails to influence source
ratings (McCroskey & Combs, 1969; Reinsch, 1971). In other studies, metaphor influences source ratings but fails to influence attitudes toward the communication topic
(Reinsch, 1974). No study has presented a formal mediational analysis that demonstrates
source impressions mediate the effect of metaphor on attitudes toward the communication topic.
Future research on this question should explicitly acknowledge that metaphor can
increase or decrease the favorability of source ratings (McGuire, 2000). As a consequence,
the effect of metaphor on source impressions should produce increased persuasion in
some circumstances and decreased persuasion in other circumstances. For example, metaphors that afford clear semantic linkages with other information contained in a communication might increase the favorability of source ratings and thereby increase persuasion in
the direction advocated. In contrast, metaphors that are irrelevant to other information
contained in a communication might reduce the favorability of source ratings and thereby
decrease persuasion in the direction advocated. Approaches that assume metaphor must
elicit a blanket positive influence on source credibility will fail to uncover more nuanced
effects of this nature.
Indirect effects mediated by the processing of literal arguments in the communication: metaphor
influences the direction of elaboration
Metaphorical language might influence the degree to which the recipient generates positive or negative thoughts about the topic when processing literal arguments contained in
a communication. Or, metaphors might influence the degree to which the recipient generates pro- or counter-arguments when processing the literal arguments. In these cases,
metaphor influences the direction of elaboration upon the literal arguments. Of course,
metaphor can only influence the direction of elaboration if message recipients are, in fact,
elaborating on the message. Therefore, these effects should primarily emerge when elaboration likelihood is high (for a related discussion, see Petty & Cacioppo, 1986). This
might result in a corresponding directional effect on attitudes toward the communication
topic. Effects of this nature have yet to be fully explored, and therefore should be considered in future research. At least three psychological mechanisms might produce this sort
of effect. Specifically, a metaphor might activate an expectancy, influence interest in the
communication, or influence the coherence of a persuasive communication. In each of
these instances, metaphors might produce an effect on attitude toward the communication topic that is mediated by the direction of elaboration.
Metaphor, expectancy, and the direction of elaboration. When a metaphor precedes literal
communication arguments, it can activate a positive or negative expectancy regarding the
topic. This might produce cognitive responses to the literal arguments that are congruent
with the expectancy, resulting in attitude change in the direction of the expectancy (see
Renstrom, Krumdick, & Ottati, 2008, for related evidence). Assume, for example, that
‘Professor Williams is an encyclopedia’ precedes ‘Professor Williams assigns a lot of homework’. In this case, the metaphor vehicle (i.e., ‘encyclopedia’) implies a positive trait
(e.g., ‘knowledgeable’). As a consequence, cognitive responses to the literal statement
may be relatively positive (e.g., ‘The homework challenges us to expand our range of
knowledge’). Alternatively, assume ‘Professor Williams is a slave driver’ precedes the same
literal statement. In this case, the metaphor vehicle (i.e., ‘slave driver’) implies a negative
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Social and Personality Psychology Compass 4/9 (2010): 783–794, 10.1111/j.1751-9004.2010.00292.x
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788 Metaphor and Persuasive Communication
trait (e.g., ‘sadistic’). Thus, cognitive responses to the literal statement may be negative
(e.g., ‘He likes to make us suffer’), and the recipient may form a negative attitude. In
most cases, the source of a communication will select a metaphor that possesses a valence
that is congruent with the desired direction of influence. Thus, in most cases, this process
should increase persuasion in the direction advocated.
To test this hypothesis, the valence of a metaphor that precedes related literal arguments should be manipulated (negative versus positive valence). After receiving the communication, participants should be asked to list their cognitive responses and rate their
attitude toward the communication topic. If the ‘expectancy hypothesis’ is correct,
valence of metaphor should produce an assimilation effect on attitudes toward the topic,
and this effect should be mediated by the direction of elaboration (number of pro-arguments minus number of counter-arguments listed).
Metaphor, interest, and the direction of elaboration. Following the lead of Aristotle, McGuire (2000) has proposed that metaphor can increase interest in the communication, and
thereby increase persuasion in the direction advocated. Other scholars have contended
that metaphorical language can elicit vivid and evocative images (Billow, 1977; Graesser
et al., 1989; Ortony et al., 1978; Paivio, 1979), excite the imagination (Mio, 1993;
Reinsch, 1971), enliven discourse (Bowers & Osborn, 1966; Zashin & Chapman, 1974),
produce a pleasurable ‘ah ha’ experience (Kreuz & Roberts, 1993; Mio, 1997), and
engage active intellectual attention (Bowers & Osborn, 1966; McGuire, 2000). Moreover,
research confirms that metaphor can indeed increase interest (Deiger & Ottati, 2002;
Kreuz & Roberts, 1993; see Read et al., 1990; for related evidence). According to
McGuire (2000), this should attract attention to the message, induce a sympathetic mood,
and thereby elicit favorable cognitive responses to the message. This model predicts that
metaphor will increase persuasion and that this effect will be mediated by interest, attention, sympathetic mood, and the generation of favorable cognitive responses.
A formal empirical test of the mediational pattern predicted by McGuire does not exist
in the literature. Moreover, McGuire (2000) has acknowledged that metaphors can reduce
interest under some circumstances, and research confirms that this is indeed the case
(Ottati et al., 1999). Clearly, McGuire’s proposed model needs to be adjusted to accommodate findings of this nature. Ottati et al. (1999) have demonstrated that a metaphor
(e.g., a sports metaphor) increases interest when it is compatible with the recipient’s personal preferences and interests (e.g., sports metaphor presented to a sports enthusiast).
Does McGuire’s (2000) model apply under conditions of this nature? It probably does
not. As will soon become apparent, effects of this nature occur when the literal arguments are strong, but the reverse effect emerges when the literal arguments are weak
(Ottati et al., 1999). Thus, even when metaphor increases interest, it does not necessarily
increase the generation of favorable cognitive responses. Although this finding is compatible with an alternative conceptualization that assumes metaphor influences the amount
(not direction!) of elaboration, it is not consistent with the implications of McGuire’s
(2000) proposed model. Thus, extant research has failed to document a pattern of findings that conforms to McGuire’s proposed model, and related work suggests interest
influences the amount (not simply the direction) of elaboration.
Metaphor, coherence, and the direction of elaboration. Independent of effects involving interest, metaphors may also influence the ‘coherence’ of a communication. Because metaphors can evoke and highlight a number of semantic pathways and relational connections
among concepts and ideas (Gentner, 1982, 1983), the accompanying arguments in a comª 2010 The Authors
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munication may be integrated together more easily and coherently when a metaphor is
present (Allbritton, McKoon, & Gerrig, 1995). Thus, metaphorical statements may provide an overarching schematic framework that guides interpretation, facilitates organization, and facilitates systematic processing of literal statements contained in a
communication (Billow, 1977; Mio, 1993, 1996, 1997; Read et al., 1990; Whaley,
1991). For example, ‘Work is an addiction’ might facilitate processing of literal statements
that indicate ‘Corporate executives are unable to relax’ or ‘Vacations make a business person anxious’. If a metaphor increases coherence in this fashion, it might increase the generation of pro-arguments (or decrease counter-arguing), and thereby increase persuasion
in the direction advocated.
This ‘cognitive coherence’ model is supported by research that indicates metaphor is
more persuasive if it appears at the onset as opposed to conclusion of a communication
(Read et al., 1990; Sopory & Dillard, 2002; for related evidence see Renstrom et al.,
2008). To guide encoding, interpretation, and organization of a message, a metaphor
should presumably be activated before (not after) the specific message arguments are processed. This model is also supported by research that suggests metaphor is most effective
at producing persuasion when the message recipient is knowledgeable with regard to the
topic domain (Johnson & Taylor, 1981; Roehm & Sternthal, 2001; Sopory & Dillard,
2002). Presumably, this is because knowledgeable individuals are better able to apply the
metaphor when encoding, interpreting, and organizing the specific message arguments.
It seems unlikely, however, that all metaphorical utterances increase cognitive coherence. Under some conditions, metaphors might confuse or distract the listener, and
thereby interfere with the listener’s ability to encode, organize, or systematically process literal statements (Billow, 1977; Frey & Eagly, 1993; Krumdick, Renstrom, Aalai, & Ottati,
2007; Mio, 1996; Mio & Lovrich, 1998). This might occur if the metaphor fails to afford
clear semantic linkages with other statements contained in the communication. Interestingly, some have suggested that this might distract listeners who would otherwise counterargue the message (Sopory & Dillard, 2002). This implies that distracting metaphors will
actually increase persuasion in the direction advocated. Of course, it is also possible that this
kind of metaphor will reduce the perceived coherence and strength of the communication
and thereby reduce favorable cognitive responses to the communication. From this
perspective, distracting metaphors should reduce persuasion. To date, research findings are
more compatible with this later possibility (Ottati et al., 1999; Sopory & Dillard, 2002).
Future research needs to more explicitly contrast conditions in which metaphor will
function as a distracter from conditions in which metaphor will increase cognitive coherence. Past research has taken an indirect approach to this question by comparing metaphor
effects on receivers possessing high versus low levels of expertise, presumably because metaphors will increase coherence more among experts but perhaps serve to confuse or distract novices. As we have noted, a more direct approach might involve manipulating the
degree to which the presented metaphor actually affords semantic linkages with the other
literal statements contained in the communication. A metaphor that semantically ‘fits’ the
literal statements should produce a coherence effect, whereas a metaphor that is irrelevant
to the literal arguments might be expected to elicit a distraction effect.
Indirect effects mediated by the processing of literal arguments in the communication: metaphor
influences process style
Just as metaphors may influence the direction of elaboration, metaphorical language may
also influence the amount of elaboration. In doing so, metaphors can elicit a process style
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790 Metaphor and Persuasive Communication
effect (Ottati et al., 1999). Inspired by dual-process models of persuasion (Chaiken, 1980;
Petty & Cacioppo, 1986), Ottati et al. (1999) posit that metaphors can influence the
degree to which message recipients engage in central or systematic processing. Central
(i.e., systematic) processing occurs when the message recipient carefully attends to, scrutinizes, and elaborates on communication arguments. It is marked by increased generation
of message-relevant cognitive responses, decreased generation of irrelevant cognitive
responses, as well as a more complex and organized representation of the attitude object
(Chaiken, 1980; Gernsbacher, 1991; Graesser, Singer, & Trabasso, 1994; Petty & Cacioppo, 1986; Trabasso & Magliano, 1996; Woike, 1994). Importantly, central processing
increases sensitivity to argument strength when listeners’ evaluate the communication
topic (Chaiken, 1980; Eagly & Chaiken, 1993; Petty & Cacioppo, 1986). The tendency
for strong arguments to produce more persuasion than weak arguments is accentuated
when individuals engage in central processing, and reduced when central processing is
absent. A metaphor influences ‘process style’ when it influences the message recipient’s
motivation or ability to engage in central processing (Ottati et al., 1999). When this occurs,
inclusion (as opposed to exclusion) of the metaphor in the communication moderates the
effect of argument strength on attitudes toward the communication topic.
Importantly, an effect of metaphor on ‘process style’ is not equivalent to the previously
described effects of metaphor on ‘direction of elaboration’. The ‘process style’ models
presume that the direction of elaboration is predetermined by the strength of the literal
communication arguments. That is, strong literal arguments are assumed to elicit proarguments whereas weak literal arguments are assumed to elicit counter-arguments. A
metaphor that promotes central processing should therefore increase the generation of
pro-arguments if the literal message arguments are strong but increase counter-arguments if
they are weak. A metaphor that reduces central processing should decrease pro-arguments
if the literal message arguments are strong but decrease counter-arguments if they are
weak. Of course, a metaphor cannot increase central processing if the message recipient is
already engaging in extremely high elaboration. Likewise, a metaphor cannot decrease
central processing if the recipient is already engaging in extremely low elaboration.
Therefore, the effect of metaphor on process style should primarily emerge when elaboration likelihood is initially at a moderate level (see Petty & Cacioppo, 1986 for a related
discussion).
Metaphor, interest, and motivation to engage in central processing. Metaphorical language has
the potential to impact the motivation to centrally process. As noted previously, many
researchers have proposed that metaphorical language increases interest in a communication (Billow, 1977; Graesser et al., 1989; McGuire, 2000; Mio, 1993; Ortony et al.,
1978; Paivio, 1979; Zashin & Chapman, 1974), and this claim has been empirically confirmed (Deiger & Ottati, 2002; Kreuz & Roberts, 1993; see Read et al., 1990, for related
evidence). If metaphor increases interest in a communication, it might motivate central
processing of literal arguments contained in the communication. That is, inclusion (as
opposed to exclusion) of metaphorical content in a communication might increase the
generation of relevant cognitive responses and increase the effect of literal argument
strength on the recipient’s attitude toward the communication topic. As noted previously,
however, it is possible that metaphorical content can increase or decrease interest in a
communication, depending on the extent to which it resonates with the recipient’s
personal preferences and interests.
On the basis of these considerations, Ottati et al. (1999) developed the motivational
resonance model. According to this model, metaphor increases central processing among
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message recipients only if it contains content that is of personal interest to the message
recipient. If the metaphor contains content that alienates or disinterests the message recipient, it will decrease central processing. In accordance with this conceptualization, Ottati
et al. (1999) found that a sports metaphor increased central processing among sports enthusiasts, resulting in an increase in cognitive elaboration and a magnified effect of argument
strength on attitude toward the communication topic. However, the same sports metaphor decreased central processing among listeners who dislike sports, reducing elaboration
and reducing the magnitude of the argument strength effect on attitudes (see McGuire,
2000; McQuarrie & Mick, 1999; for related conceptualizations).
Metaphor, coherence, and ability to engage in central processing. A possibility that has yet to
be fully explored is that metaphor influences the message recipient’s ability to engage in
central processing. As noted previously, some theory and research suggests that a metaphor can increase the coherence of a communication, providing an overarching schematic
framework that guides interpretation, facilitates organization, and facilitates central processing of literal statements (Billow, 1977; Mio, 1993, 1996; Read et al., 1990). On the
other hand, some theory and research suggest that metaphors can also confuse or distract
the listener, and thereby interfere with the listener’s ability to process literal communication arguments (Billow, 1977; Frey & Eagly, 1993; Mio, 1996; Mio & Lovrich, 1998).
Research has yet to clearly document when metaphor will elicit a ‘coherence effect’ and
when metaphor will elicit a ‘distraction effect’. As previously noted, however, we suspect
that a critical moderating variable involves the degree to which the metaphorical utterance shares semantic linkages with the literal statements contained in the communication.
If the metaphor activates a schematic structure that affords semantic linkages with the
literal arguments, it should increase the cognitive coherence of the communication and
thereby facilitate central processing of the literal arguments. This should result in a more
organized representation of the communication topic, increased cognitive elaboration,
and an amplified effect of argument strength on attitudes toward the communication
topic. On the contrary, when the metaphor is semantically irrelevant to the literal arguments, it should function as a distracter that fails to elicit (or even reduces) central processing. This ‘process style’ hypothesis predicts that coherent metaphors will magnify the
effect of literal argument strength, whereas distracting metaphors will reduce the effect of
literal argument strength. Thus, coherent metaphors should increase the persuasiveness of
strong arguments but decrease the persuasiveness of weak arguments. Conversely, distracting metaphors should decrease the persuasiveness of strong arguments but increase the
persuasiveness of weak arguments. Clearly, these ‘process style’ effects differ from effects
predicted by the ‘direction of elaboration’ models described earlier.
Conclusion
Metaphor serves multiple functions in persuasive communication, and the effect of metaphor on persuasion is potentially mediated by multiple psychological process mechanisms.
Nevertheless, we propose that past and future research in this area can be organized or
grouped into three simple categories. First, metaphorical statements can activate information that is directly applied to the communication topic and thereby influence attitudes
toward the communication topic. Second, metaphorical language may influence impressions of the communication source and thereby impact attitudes toward the communication topic. Third, metaphors may affect attitudes toward the communication topic by
influencing the direction or amount of elaboration that takes place when recipients
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Social and Personality Psychology Compass 4/9 (2010): 783–794, 10.1111/j.1751-9004.2010.00292.x
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792 Metaphor and Persuasive Communication
process literal statements contained in the communication. In each of these cases, the psychological processes that mediate the effect of metaphor on persuasion operate in some
conditions more than others. In addition, these process mechanisms can be expected to
increase persuasion in some circumstances but decrease persuasion in other circumstances.
Thus, the critical question is not ‘Does metaphor increase persuasion?’ To the contrary,
future research should focus on a more subtle and nuanced set of questions. Namely,
under what conditions does metaphor elicit a given psychological process (e.g., attributemapping versus valence-transfer)? And, under what conditions will a given process result
in an increase versus decrease in persuasion? We look forward to additional research that
addresses these fundamental questions.
Acknowledgement
This study was funded by a National Science Foundation grant awarded to the first
author (NSF Grant No.0518007).
Short Biographies
Victor C. Ottati received his bachelor’s degree from the University of Michigan and
received his PhD in Psychology from the University of Illinois. He has served as an Assistant Professor at SUNY Stony Brook and Purdue University. He is currently Professor of
Psychology at Loyola University Chicago and Associate Editor of Basic and Applied
Social Psychology. He is a social psychologist with interests in the areas of attitudes and
social cognition, persuasive communication, stereotyping, affect and social judgment,
metaphor and social information processing, political psychology, political communication, cross-cultural psychology, and consumer psychology.
Randall A. Renstrom received a BS in Psychology from the Ohio State University, an
MA in the Social Sciences from the University of Chicago, and is currently a PhD candidate in Social Psychology at Loyola University Chicago. His research interests are in the
areas of attitudes, social information processing, persuasive communication, political communication, political candidate evaluation, and political ideology.
Endnote
* Correspondence address: Department of Psychology, Loyola University Chicago, 1032 W. Sheridan Rd., Chicago, IL 60660, USA. Email: [email protected]
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Social and Personality Psychology Compass ª 2010 Blackwell Publishing Ltd