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Journal of Personality and Social Psychology
1976,
Vol. 34, No. 4, 615-624
Speed of Speech and Persuasion
Norman Miller, Geoffrey Maruyama, Rex Julian Beaber, and Keith Valone
University of Southern California
The relationship between speaking rate and attitude change was investigated
in two field experiments. Manipulations of speech rate were crossed with (a)
credibility of the speaker and (b) complexity of the spoken message. The re-
sults suggest that speech rate functions as a general cue that augments credi-
bility; rapid speech enhances persuasion. No support was obtained for infor-
mation-processing interpretations of the effects of a fast speaking rate. The
increased persuasion produced by fast speech could not be attributed to dis-
ruption of effective counterarguing. These findings emphasize the importance
of perceptual and evaluative factors in the persuasion process at the expense
of a more rationalistic information-processing view of how man responds when
confronted with an influence attempt.
Although many of the persuasive communi-
cations received during daily life are orally
presented, the characteristics of speech that
affect persuasion are rarely studied. More-
over, studies that do examine delivery style
typically treat it as a global variable. For
instance, Dietrich (1946) studied the dyna-
mism of a speaker's style, Bettinghaus (1961)
assessed the effects of overall speaking effec-
tiveness by comparing trained and uncoached
students, and Bowers (1965) examined the
effects of extroverted and introverted deliv^
ery using dramatic arts students to simulate
style.
The persuasive effects of more discrete
characteristics of oral delivery, such as inten-
sity, pitch, speed of presentation, or specific
emotional qualities apparently more rarely
elicit attention.
Several considerations suggest that speech
rate might be an important variable. Texts on
speech (Allen, Anderson, & Hough, 1968;
Monroe & Ehninger, 1974) have reported
considerable individual variation in speaking
rate with 120-180 words per minute as the
lower and upper limits of normal speech.1 It
is a short step to imagine theoretical implica-
Preparation of this article for publication was
aided by support from National Institute of Mental
Health Grant MH26094, awarded to the first author,
and a Haynes Foundation Fellowship to the second
author.
Requests for reprints should be sent to Norman
Miller, Department of Psychology, University of
Southern California, University Park, Los Angeles,
California 90007.
tions of such variation that might contribute
to differences in persuasion. Yet, even though
Foulke and Sticht (1969) have most recently
studied the effects of speed of presentation on
comprehension, its effects on persuasion re-
main unexplored.
McGuire (1969) characterized attitude
change as a stochastic process that flows
from attention through comprehension, yield-
ing, retention, and action. Although rate of
speaking might theoretically be expected to
influence any of these processes, it initially
seems plausible to focus on how it affects com-
prehension. In their review, Foulke and
Sticht (1969) showed that when significant
results are found, most are in the direction
of lowered comprehension when speed of
speech is rapid.2
If a fast speaking rate does reduce com-
prehension, then it should also curtail per-
suasive power (Eagly, 1974). However, since
the results of most studies in the comprehen-
sion literature are not significant, it may
make more sense to look for the effects of
speed in some other stage of the persuasive
process, such as yielding. To focus away from
comprehension seems particularly sensible, in
1 For example, radio announcers are often noted
for their rapid speech rate. Lumley (1933) deter-
mined the average speech rate of 25 radio speakers
to be 162 words per minute, with a standard devia-
tion of 19.40 words per minute.
2 It should be pointed out that a majority of the
studies have found no significant effects.
615
616MILLER, MARUYAMA, BEABER, AND VALONE
that the high speeds used in the prior re-
search equaled or exceeded the upper limits
of the range of normal speech. Consequently,
one might reasonably assume that the speed
manipulations in these studies were suffi-
ciently powerful to have shown an effect if
one does indeed exist.
How might speed affect the yielding phase
of persuasion? A fast speaking rate might dis-
rupt any covert attempt to counterargue
against the persuasive content of the message,
thereby increasing persuasion. Whereas any
effects of speed on comprehension or counter-
argument disruption can be conceptualized as
message factors—characteristics of the mes-
sage that affect persuasion—speaking rate
may alternatively act as a source factor. That
is,
it might provide cues for viewing a fast
speaker as more knowledgeable, competent,
and facile. In this case a rapid speaking rate
constitutes a credibility cue and on this basis
should likewise enhance persuasion.
Although the comprehension interpretation
of speaking rate does make a distinct predic-
tion—less attitude change when speech is
rapid—both the counterargument disruption
and enhanced credibility interpretation make
the opposite prediction—greater attitude
change with a rapid speaking rate. How can
these two hypotheses be separated? First,
with respect to the counterargument disrup-
tion hypothesis, if rapid speech does indeed
disrupt covert counterarguing, then, as im-
plied by Kiesler and Mathog (1968), the im-
pact of speaking rate should vary with the
credibility of the speaker. According to their
argument, when the message is counteratti-
tudinal and the speaker possesses substantial
credibility, counterarguing tends to become
the most viable mode of resisting influence.
This should be particularly true if one is
highly involved in the issue (Osterhouse &
Brock, 1970). However, counterarguing is or-
dinarily an elaborate internal response, one
requiring time and mental energy. A com-
munication spoken rapidly should reduce the
available time and increase the difficulty of
making such covert responses. Consequently,
increased speed should facilitate attitude
change. On the other hand, a person listening
to a speaker who lacks credibility can resist
influence by using a less elaborate internal
response; he can simply reject or discount
what is said. Under these conditions, speaking
rate should not substantially attenuate ability
to resist, and consequently, should have little
impact on persuasion. Although there are few
direct tests of the role of counterarguing in
the persuasion process (Miller & Baron,
1973),
the reasoning above does make a clear
prediction. It suggests that if fast speech does
disrupt counterarguing, there should be an
interaction between speaking rate and credi-
bility. Alternatively, if speaking rate simply
functions as a credibility cue, no interaction
would be predicted. Instead, as previously
suggested, fast speech should enhance per-
suasion regardless of the speaker's credibility.
The results of two studies that begin to
delineate the relation between speed of speech
and persuasion (Beaber & Miller, Note 1)
suggest that speech rate functions as a cue
for increased credibility. The first experiment
of Beaber and Miller investigated rate of
speaking and credibility of the source in a
2X2 design. In addition to finding the credi-
bility manipulation to be successful (the high-
credibility source was seen as more knowl-
edgeable and more trustworthy), the fast
speaker was perceived as more knowledgeable
and more trustworthy. In addition, the com-
munication was perceived as more complex
but also clearer and easier to understand
when presented by a fast speaker. These find-
ings suggest that a rapid speaker is perceived
as more competent, since it takes a skilled
speaker to present complex material clearly.
However, since credibility was manipulated
by varying both ability and trustworthiness
in this first study, the specific component of
credibility that speed enhanced cannot clearly
be specified. Certainly, there are situations in
which high ability and trustworthiness do not
necessarily occur together. The most obvious
example is a used car dealer who, despite his
expertise, is not always viewed as trust-
worthy and may be seen as even less believ-
able if he speaks very rapidly.
Therefore, in a second experiment Beaber
and Miller manipulated trustworthiness inde-
pendently from expertise to investigate
whether or not the persuasiveness of an un-
trustworthy communicator would be enhanced
by rapid speech. In the first study, any effects
SPEED OF SPEECH AND PERSUASION617
of trustworthiness could have been obscured
by the difference in expertise of the com-
municator. Whereas in the first experiment
the communication advocated "offshore dril-
ling for oil," in the second experiment it
argued that "The Mazda is the best car value
around." The communicator was depicted as
a used Mazda salesman with something to
gain from his persuasiveness (low trust) or as
a former Mazda salesman who currently
worked in a bank (high trust). Thus, exper-
tise was held constant. This manipulation
seemed most likely to produce an interaction
between speed and credibility and thereby
test the generality of speed as a cue for en-
hanced credibility. In this instance, an un-
trustworthy fast speaker should appear to be
less believable than an untrustworthy slow
speaker; contrarily, a trustworthy fast speaker
should be more believable than a trustworthy
slow speaker, replicating the outcome of the
first study.
Manipulation checks showed that the trust-
worthy speaker was in fact rated as more
trustworthy and, furthermore, that the manip-
ulation was independent of expertise, since
the high- and low-trust speakers were rated
as equally knowledgeable. As in the first ex-
periment, rapid speech enhanced ratings of
both trust and knowledge. Further paralleling
the first experiment, measures of persuasion
also showed the rapid speaker to be more
persuasive.
In summary, then, these two experiments
strongly argue that speaking rate operates as
a very general and powerful credibility cue.
The results clearly contradict information-
processing hypotheses concerning rate of
speech. If fast speech had impaired compre-
hension, it should have likewise reduced
rather than augmented persuasion. Alterna-
tively, as argued in the first experiment, if
fast speech had interfered with covert counter-
arguing, it should have more strongly facili-
tated persuasion when credibility or trust-
worthiness was high than when it was low.
If, despite the data of these two experi-
ments, one is intent on saving the compre-
hension or counterargument disruption hy-
potheses, one might argue that the proper
tests have not been performed. Since both of
these experiments were laboratory studies,
subjects might have construed the situation
as a test. Consequently, the predicted inter-
action between credibility and speech rate
might have failed to receive support because
the situation demanded extremely high atten-
tion regardless of the level of the speaker's
credibility. Thinking that they might subse-
quently be tested on some aspect of their re-
tention or comprehension, subjects might have
focused more on the content of the arguments
regardless of the level of credibility assigned
to the speaker. According to this view, where-
as faster speech might indeed produce some
minor enhancement of credibility, its more
important, potent, pervasive, and normal con-
sequences are those affecting information
processing, whether decreasing comprehension
or alternatively disrupting one's ability to
counterargue. Yet, in laboratory experiments,
these effects cannot be observed; attention
and vigilance to content is made so asymp-
totically high by the implicit demands of the
laboratory that the normally weaker and less
important credibility enhancement effects re-
main as the only ones to be observed.
In terms of these arguments, a field setting
might provide a more adequate test of the
information-processing interpretations of
speaking rate. Since the public accepts on-
the-street interviewing with little suspicious
questioning, test expectancies might not op-
erate when a field experiment is concealed
behind this type of facade.
EXERIMENT 1
Experiment 1 manipulated speech rate and
speaker credibility in a field setting to deter-
mine their effect on attitude change and per-
ceptions of the speaker. Since in the Beaber
and Miller (Note 1) experiments the trust-
worthiness dimension of credibility did not
interact with speech rate but rather func-
tioned as a cue that unidirectionally enhanced
credibility, no attempt was made to manipu-
late orthogonally the competence and trust-
worthiness dimensions of credibility.
Method
Subjects and experimenters. Subjects were 359 per-
sons living in the Los Angeles area. They were indi-
vidually approached in a public area by 1 of 14 ex-
perimenters, each of whom conducted multiple repli-
618MILLER, MARUYAMA, BEABER, AND VALONE
cations of the design.
3 Experimenters were male and
female undergraduates enrolled in an upper-division
psychology class at the University of Southern Cali-
fornia.
Procedure. Each experimenter assigned a subject
to each cell before starting the next replication. The
order of cells was determined by random assignment
but was constant across replications and experi-
menters. All subjects were individually run. They
were approached in a variety of public settings, such
as parks, various on-the-street locations, other
campuses, shopping malls, and door-to-door in vari-
ous neighborhoods.
The experimenter approached the prospective sub-
ject and introduced himself (herself) as an inter-
viewer from radio station KSC for the program
People's Forum, which was described as being con-
cerned with topics of interest to the listening audi-
ence.
Subjects were told that tapes had been made
containing listeners' opinions on various topics. The
interviewer asked the subject to listen to a tape on
the current day's topic ("The danger of drinking
coffee") and then to give his reaction to it. If the
subject agreed, the interview was continued by
describing the author of the tape and playing it for
the subject.
Persuasive communication. The communication
was approximately 400 words in length. It argued
that coffee is a hazardous drug; caffeine in large
doses is a poison and can cause damage to and
fluttering of the heart, headaches, migraines, cold
hands,
and stomach ulcers; by decreasing appetite
and by leading to insufficient sleep, coffee lowers
resistance to disease; by providing momentary en-
ergy, it hides symptoms of other medical problems;
it adversely affects teeth and gums; it is addicting
and causes withdrawal symptoms; and in conclusion,
like cigarettes, it should be classified by the govern-
ment as hazardous.
Credibility. In the low-credibility condition the
speaker was introduced as a locksmith, whereas in
the high-credibility condition he was introduced as
a biochemist. To augment the credibility manipula-
tion, errors in pronunciation, grammar, and word
usage were inserted into the speech of the low-credi-
bility speaker, while retaining the same content and
meaning. After describing the speaker, the experi-
menter played either a fast or slow version of the
recorded message and then asked the subject to
answer a few questions.
Speaking rate. The speaker used in this experiment
spoke at approximately the same rates as did the one
in the Beaber and Miller (Note 1) experiments. The
speaking rate in the low-speed condition averaged
102 words per minute, whereas in the high-speed
condition it averaged 195 words per minute.4 These
rates were achieved by simply instructing the speaker
to practice delivering the speech as rapidly and
slowly as possible while controlling his level of en-
thusiasm and involvement. Tapes were made on
studio-quality equipment. Overall volume was bal-
anced across tapes by matching average volumes on
five sample segments of each tape. Cassette record-
ings were reproduced from the master tapes and
delivered via cassette recorders.
Dependent measures. After listening to the tape,
subjects were asked to indicate orally their agree-
ment with a series of statements. Agreement was
indicated on 10-point Likert scales (midpoint = S.S),
with higher numbers indicating stronger agreement.
The statements concerned global agreement with the
main contention of the communication, perceived
speaker characteristics (knowledgeability), perceived
clarity of the presentation, and the personal coffee-
drinking habits of the subject.
Results
Inspection of the credibility manipulation
check indicated that the high-credibility
source was perceived as more knowledgeable:
Ms — 7.93 and 5.19 in the high- and low-
credibility conditions, respectively;
/*\1,
13)
= 89.1, p < .001. This effect was determined
by testing the main effect against the Experi-
menter X Condition interaction, since this
interaction was significant.5 This most con-
servative test (using the significant interac-
tion term) also revealed a significant effect of
credibility on perceived understanding: Ms
= 8.71 and 8.07 in the high- and low-credibil-
ity conditions, respectively; 7^(1,13) = 7.8,
p < .05. The effect of speech rate on knowl-
edgeability approached standard levels of
significance: Ms = 6.93 and 6.12 in the fast-
3 The authors wish to express their sincere appreci-
ation to Susan Anderson, Evie Baker, Laurie Brand,
Pat Brotman, Gayle Caviglia, David George, Med-
rith Hose, Judi Kammerman, David Mace, Steve
Mayer, David Quezada, Alan Seims, Francis Troll,
and Jan VanSchaik for their able assistance in the
collection of the data.
4 The high-credibility-slow-speech rate was 99.6,
the high-credibility-fast-speech rate was 194.4, the
low-credibility-slow-speech rate was 104.8, and the
low-credibility-fast-speech rate was 195.8 (words
per minute). For the two Beaber and Miller (Note
1) studies, a rate of about 110 words per minute
was used in the slow-speech conditions, while a rate
of about 190 words per minute was used in the fast-
speech conditions. Despite the similarity of speech
rates,
the different communicator used in the present
study should increase the generalizability of the
results.
5 Different experimenters produced different mag-
nitudes of effect with the credibility manipulation.
Therefore, each effect was tested against its inter-
action with experimenters. In effect, then, we are
using a mixed model with experimenters as a random
factor, testing each fixed effect against its interaction
with experimenters.
SPEED OF SPEECH AND PERSUASION619
and slow-speech conditions, respectively; F(l,
13) = 4.4, p <
.0.6,
again, by the more con-
servative test. Thus the high-speed speaker
tended to appear more knowledgeable.
An analysis of variance on the postcom-
munication agreement measure (using number
of cups of coffee drunk daily as a covariate)
yielded main effects that approached signifi-
cance when tested with the conservative ex-
perimenter interaction error term: Ms = 6.13
and 5.44 in the high- and low-speed condi-
tions,
respectively; F(l, 13) = 2.80, p < .13;
Ms = 6.28 and 5.33 in the high- and low-
credibility conditions, respectively; F(l, 13)
= 4.41, p < .06. Thus the high-speed com-
munication was more persuasive than the low-
speed communication.6 The fact that the ex-
perimenters used in this study lacked much
experience (which probably accounts in large
part for the Experimenter X Condition inter-
actions) might well have reduced the strength
of the effect of speech rate. Further, some re-
searchers have argued that effects in the
field are typically weaker than those in
the laboratory (Hoviand, 1959). In addi-
tion, examination of the tapes revealed
an instance of a glaring nonfluency (re-
peated stuttering over one word) in the
high-credibility-high-speed speech. As shown
by Miller and Hewgill (1964), nonfluen-
cies typically lower perceived credibility.
Consequently, this should have further re-
duced the effect of the speed manipulation.
Despite these difficulties, it should be noted
that the data did not support either the com-
prehension prediction—less persuasion under
high speed—or the counterargument predic-
tion—a Speaking Rate X Credibility interac-
tion showing a speed effect under high-credi-
bility conditions but no speed effect in low-
credibility conditions.7 Instead, they support
the view that rapid speech serves as a credi-
bility cue and thereby enhances persuasion.
EXPERIMENT 2
Although the credibility hypothesis con-
tinued to receive general support from Experi-
ment 1, there may still be special circum-
stances in which speech rate functions to dis-
rupt counterarguing. The communications
used in both Beaber and Miller (Note 1)
studies and in Experiment 1 did not provide
especially novel arguments to the listener, nor
did they deal with particularly unfamiliar
topics. In persuasion paradigms that offer
novel arguments or topics, adequate process-
ing of message content should become more
salient. From this standpoint, it can be
argued that for the topics used in the re-
ported studies, subjects had counterarguments
readily available and therefore did not experi-
ence the high rate of presentation as being
disruptive. Elaborate processing of the mes-
sage was not necessary. A more sensitive test
of the counterargument disruption hypothe-
sis might require novel communications for
which simple retrieval of stock counterargu-
6 All effects are highly significant (p < .01) when
the standard, and less conservative, within-cell vari-
ance is used as the error estimate. However, to
revert to this more typical error estimate means
that these results cannot be generalized beyond the
particular set of experimenters used to collect these
data. This is of course normally true for virtually
all experiments reported in psychological journals, in
that few researchers test their effects against the
variability of different experimenters' outcomes.
Most use only a single experimenter. If the results
were significant using the more conservative error
estimate (the interaction with experimenters), their
external validity would be enhanced in that they
presumably would obtain with any of the experi-
menters from the larger population of which these
14 constitute a random sample.
7 In attempting to defend the counterargument
explanation, some might argue that people primarily
use covert counterarguing to resist persuasion when
they are involved with or have a personal concern
about the topic. While we have not explicitly ma-
nipulated involvement, we can indirectly explore
this notion by attending to an individual difference
measure of the extent to which our subjects were
likely to be concerned with the topic. It is reason-
able to assume that subjects who report being heavy
coffee drinkers are likely to be more concerned and
involved with a speech emphasizing the dangers of
drinking coffee. The results of the analysis of covari-
ance argue against the view that covert counter-
arguing is used to resist persuasion primarily when
one is concerned with the issue. The persuasion ef-
fects are found even though personal involvement
(number of cups of coffee drunk per day) was co-
varied out. If speech rate affects persuasion by inter-
fering with counterarguing and if counterarguing
only occurs when the topic is involving, removing
the effect of involvement via covariance analysis
should also eliminate any effect of speech rate on
persuasion,
620MILLER, MARUYAMA, BEABER, AND VALONE
ments would not suffice as a means for re-
sisting influence. Therefore, for the present
experiment, a novel topic, "The dangers of
hydroponically grown vegetables," was chosen
to ensure that subjects would be forced to
process novel arguments.
Although a more sensitive test of the
counterargument hypothesis might be created
by using a more novel communication topic
and simply replicating one of the earlier stud-
ies that examined the Speech Rate X Speaker
Credibility interaction, a more potent criti-
cism of the initial experiments would still re-
main unresolved. The predicted Speed X
Credibility interaction rested solely on the
hypothesized differential salience of counter-
arguing as a means of belief defense in high-
versus low-credibility conditions. Although
Kiesler and Mathog (1968) provided experi-
mental support for the assumption that
counterarguing is the preferred mode of de-
fense when the speaker possesses high credi-
bility, alternate interpretations of their data
are possible (Baron, Baron, & Miller, 1973).
In addition, since a credibility manipulation
only indirectly affects orientation toward con-
tent, it is difficult to specify the range over
which content orientation is varied. Failures
to produce the predicted interaction may only
reflect a weak manipulation of orientation
toward and away from content.
A more direct test of the counterargument
hypothesis should use variables more clearly
related to information processing. Theoreti-
cally, message complexity should have more
pronounced effects on the difficulty of pro-
cessing information. Indeed, highly complex
messages may force the listener to restrict his
or her covert activity and focus entirely on
message comprehension. With complex com-
munications, processing difficulties should be
near their ceiling, leaving little room for speed
effects. However, with simpler messages, an
increased rate of speech should reduce the
available time for counterargument produc-
tion, thereby facilitating persuasion. In sum,
there should be an interaction of speed and
message complexity on attitude change.
To test the interaction predicted by an
information-processing model, Experiment 2
manipulated speech rate and message com-
plexity in a 3 X 2 factorial design using a
"novel" topic. Three levels of speaking rate
were employed to ensure that the effects of
speech rate are not curvilinear and to extend
further the generality of earlier findings.
Method
Subjects. A total of 90 males and females, chosen
from the mall of a large open-air shopping center,
participated in the study.
Procedure. Subjects were randomly assigned to
the six cells of the design before replication. The
procedure and facade largely paralleled that of Ex-
periment 1. The experimenter approached subjects
individually and introduced himself as an interviewer
from radio station KSC who was interviewing peo-
ple on the street for the program People's Forum,
which was again described as being concerned with
topics of interest to the radio audience. Subjects
were told that tapes had been made containing lis-
teners' opinions on various topics. The interviewer
asked the subject to listen to a tape on the topic of
the day ("The dangers of hydroponically grown
vegetables"). If the subject agreed to hear the tape,
the interview was continued by describing the author
of the tape and playing the tape for the subject.
The speaker was ostensibly introduced as Charles
Travis, a produce manager at Ralph's Ranch Market
in Hollywood. The topic of the tape was chosen
because it had been previously determined that few
people know what the term hydroponics means, let
alone understand the arguments favoring or opposing
hydroponic growing methods. Lacking arguments,
subjects are unlikely to have a defensible attitude
regarding the value of hydroponics.
Persuasive communication. The communication
was approximately 300 words in length. After defin-
ing hydroponics, it mentioned a number of "prob-
lems"
with hydroponic methods: the need for fre-
quent tests to ensure proper chemical concentrations
in the growing medium, the small size of crops pro-
duced, the excessive cost of and trouble with equip-
ment, algae on crops, and finally, cellular defects and
genetic abnormalities of crops.
Speaking rate. Fast, moderate, and slow tapes
were all delivered by the same person (but not the
speaker used in Experiment 1). The average speech
rates were 191, 140, and 111 words per minute in
the fast-, moderate-, and slow-speech condition,
respectively. The speaker practiced the delivery of
the speech six times immediately before taping. In
addition, the slow-speech version was recorded first.
It was hoped that these measures would reduce
differences in patterns of inflection between condi-
tions.
Message complexity. The content of the two com-
munications was the same. As described above, it
argued against the use of hydroponic methods of
growing vegetables. In the simple communication the
ideas were expressed in simple (vs. compound) sen-
tences with few parenthetical or qualifying clauses.
In the complex communication the very same ideas
were expressed in compound sentences (formed by
SPEED OF SPEECH AND PERSUASION621
combining the simple sentences of the simple com-
munication). In addition, the complex message used
extended qualifying clauses, set in a sequence that
would be confusing without careful attention and
complete comprehension.
Dependent measures. After listening to the tape,
subjects were asked to indicate orally their agree-
ment with a series of attitude statements. Agreement
was indicated on a 10-step scale (1-10), with higher
numbers indicating greater agreement. In addition to
measuring agreement with the speaker, there were
questions to measure perceptions of the speaker's
intelligence, knowledge, and objectivity.
Results
Since no predictions were made regarding
main effects for message complexity (i.e., it
was primarily included to investigate the
presence of Complexity X Speed interactions),
message complexity was analyzed by a multi-
variate analysis of variance across all de-
pendent variables. This analysis indicated no
differences between complexity conditions. In
addition, there was no hint of a Message
Complexity X Speaking Rate interaction, as
predicted by the counterargument disruption
hypothesis for measures of persuasion (i.e.,
agreement with speaker). These data argue
that speech rate does not affect counter-
arguing. In consonance with this interpreta-
tion, although Chaiken and Eagly (1976)
found that complexity decreased persuasion,
they found no relation between their com-
plexity manipulation and counterarguing.
In the absence of a significant interaction,
the focus should turn to the main effects for
speed of presentation. A faster rate of speech
produced more persuasion: 77(2,84) =4.00,
p < .02; Ms = 4.62, 5.95, and 6.10 for low-,
moderate-, and high-speed messages, respec-
tively. Furthermore, in consonance with Ex-
periment 1, faster speech resulted in percep-
tions of greater intelligence: F(2, 84) = 2.31,
P<A;
Ms =5.70, 6.45, and 6.83; greater
knowledge: F(2, 84) .= 2.59, p < .08; Ms =
6.46, 6.80, and 7.53; and more objectivity:
JF(2,84)
=4.41,
p<.01;
Ms = 3.83, 3.93,
and 5.76.
Taken together, these results provide strong
support for the credibility enhancement inter-
pretation of speaking rate. They offer no sup-
port for the conuterargument hypothesis and
essentially replicate the data from the first
experiment and the Beaber and Miller (Note
1) studies. In addition, the linear progression
of means for both the agreement measure and
the speaker perception measures adds greater
generality to the earlier studies and argues
against curvilinear effects within the normal
range of speech rates.
GENERAL DISCUSSION
The data of these field studies support the
notion that rapid speech functions as a credi-
bility cue. In this regard, it is noteworthy that
across several messages and speakers, as well
as in both laboratory and field settings, rap-
idly spoken communications were more per-
suasive than those spoken slowly. Indeed, one
might be inclined to assert confirmation of a
new law: "Beware of the fast talker." How-
ever, it is important to point out that while
these studies primarily manipulated speech
rate and did attempt to control some of the
obvious variables such as volume, enthusiasm,
etc.,
that apparently naturally covary with it,
in no sense can we claim that our effects are
entirely or purely attributable to speed of
speech. There may yet be residual factors,
naturally co-occurring with rapid speech rates,
that enhance persuasion. Only with computer-
assisted construction of experimental materials
can we hope to isolate speed per se as the
critical factor. In support of our own interpre-
tations, however, Smith, Brown, Strong, and
Rencher (1975) have used computer-assisted
manipulation of speech rate and have shown
that greater competence is attributed to those
who speak at a faster rate.
It is also interesting that fast speech within
the normal range apparently does not inter-
fere enough with reception to disrupt com-
prehension. While we have tended to empha-
size the imperviousness of comprehension to
speech rate, it is worth noting that it was not
directly assessed in the present studies. Conse-
quently, an ancillary view is that whereas
speech rate may well affect comprehension
(when adequately measured), comprehension
in and of itself is not very important in the
persuasion process.
While we have generally argued that the
data oppose the counterargument disruption
hypothesis, one other interpretation warrants
consideration, namely, the effort justification
effect, which is derived from dissonance
622MILLER, MARUYAMA, BEABER, AND VALONE
theory. Rapid speech may enhance persuasion
by increasing the effort required to process
and comprehend the speech content ade-
quately. The enhancing effects of effort on
persuasion are well documented (Osterhouse
& Brock, 1970; Zimbardo, 1965; Zimbardo &
Ebbesen, 1970). Baron et al. (1973) argued
that such effort expenditure need not involve
physical activity but might simply be a
psychological or cognitive process. If so, rapid
speech might produce its effect as a conse-
quence of the increased effort required to
comprehend it.
Another consideration is that the present
research used paradigms in which the listener
could not interact with the speaker. The im-
pact of stylistic variables in social interaction
paradigms may be quite different. High speech
rate may reduce opportunities for response in
a conversation by eliminating pauses. Under
these circumstances, a listener may find a
high speech rate frustrating and consequently
might resist influence.
Finally, the effect of the manipulation of
complexity in Experiment 2 warrants addi-
tional consideration. From the standpoint of
traditional learning theory approaches to per-
suasion, the failure to find a main effect of
less persuasion with a more complex message
seems puzzling. Indeed, Chaiken and Eagly
(1976) find empirical support for this
expectation. Yet, further reflection on and
comparison of their procedures with our own
suggests numerous reasons for the discrepancy
between findings and, further, suggests cir-
cumstances under which one might expect a
highly complex message to reduce persuasion.
Complexity should interfere with persuasion
in circumstances where comprehension of con-
tent critically affects the persuasion process.
The following are circumstances that might
maximize the importance of comprehension.
1.
The communication topic should disin-
cline one to rely on expert opinion. Rather,
one's opinion should rest largely on one's own
values in combination with an understanding
of the relevant facts. The facts should not be
too technical but relatively easy for the lis-
tener to understand and should have a mean-
ing instrumental to the appropriate implemen-
tation of one's values when forming a final
opinion on the topic.
2.
The communication must be lengthy.
The number of facts must be sufficiently sub-
stantial, detailed, and interrelated to leave
one puzzled about how one's values apply to
the "proper" concluding opinion, unless one
does possess a fairly complete understanding
of the facts regarding the issue.
3.
Finally, one's task should not simply
require that one offer an opinion. Instead,
stemming from one's opinion, there should be
action or behavioral consequences, which if
not intended for
oneself,
should apply to oth-
ers.
If there are no direct and personal deci-
sion consequences, the topic of communication
should at least be one that is similar to those
for which there were decision consequences
in the past.
When we consider the topic used by Chai-
ken and Eagly (1976) and compare it with
our own, our failure to find complexity effects
becomes more understandable. Our topic, the
danger of hydroponically grown vegetables,
was novel to most respondents. It argued,
largely on the basis of unfamiliar technical
information, for a conclusion that the listener
essentially had to accept on faith. Further, its
length was brief (approximately 300 words).
On the other hand, their communication, the
"Victoria Company Case," was preceded by
a handout that provided background infor-
mation concerning a dispute between the
company and its newly organized union em-
ployees over the fact that the management
had failed to provide the Christmas bonus
that the workers had typically received. For
this preliminary information, presenting both
union and company views, subjects were given
approximately 5 minutes to process the infor-
mation. Then they received the "case discus-
sion" of a law student who was presumably
playing the role of the lawyer brought in to
arbitrate the case. This "case discussion"
constituted the persuasive communication and
was at least three times the length of our own
persuasive appeal. Finally, it is important to
note that the subjects were led to believe
that they were assisting the psychology de-
partment in evaluating the ability of students
at a New England law school to argue legal
SPEED OF SPEECH AND PERSUASION623
cases.
In other words, their expressed opinion
would have action consequences for others*
The procedure used by Chaiken and Eagly
(1976) to manipulate complexity largely
paralleled our own. Yet, from the standpoint
of our preceding arguments, it should be ap-
parent that adequate information processing
(comprehension) should play a much more
central role in determining subjects' accept-
ance of the recommended conclusion in their
case than in our own. In summary, whereas
our field experiments may reflect general
tendencies of persons to avoid complex cogni-
tive effort and form judgments based upon
simple decision rules (e.g., the speaker seems
trustworthy vs. untrustworthy, etc.), there
are other instances in which judgments are
sufficiently important to ensure that neces-
sary cognitive effort will be expended (e.g.,
buying a car, being on a jury). In these latter
instances, there are apparently some specific
situations (as described above) in which
complexity does affect persuasion.
In conclusion, it is important to note that
the three hypothesized consequences of a
fast speaking rate explored in this research
reflect two views of the persuasion process,
one emphasizing rationality or the importance
of detailed information processing and the
other deemphasizing it. The treatment of the
persuasion process by social psychologists has
tended to take a rationalistic view of man
(e.g., Festinger & Maccoby, 1964; Hovland,
Janis,
& Kelly, 1953; Jones & Gerard, 1967;
McGuire, 1969). More recently, Miller (Mil-
ler, 1968; Miller & Baron, 1973) has argued
that this view may require modification, with
greater weight being accorded instead to emo-
tional and evaluative cognitions—at the ex-
pense of information, content-oriented cogni-
tions.
If the impact of speaking rate on attitude
change were mediated by either comprehen-
sion effects or counterargument disruption,
then a highly rationalistic view of the per-
suasion process would have been supported.
However, the findings, which support the
credibility interpretation of speaking rate, are
consistent with a less rationalistic view of the
persuasion process. Indeed, to put it somewhat
sardonically, it may be irrational to rationally
scrutinize the plethora of counterattitudinal
messages received daily. To the extent that
one possesses only a limited amount of infor-
mation-processing time and capacity, such
scrutiny would disengage the thought pro-
cesses from the exigencies of daily life*
REFERENCE NOTE
1.
Beaber, R. J., & Miller, N. The effects of speech
rate on attitude change. Unpublished manuscript,
University of Southern California, 1974.
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