Journal ol Personality and Social Psychology
1974, Vol. 30, No. 6, 741-747
DISCUSSION EFFECTS ON MILITARISM-PACIFISM:
A TEST OF THE GROUP POLARIZATION HYPOTHESIS l
DAVID G. MYERS 2 AND PAUL J. BACH «
Hope College
Group-induced change processes were examined in two experiments using a
military decision simulation. In Experiment 1, groups of relatively pacifistic
subjects (doves) and groups of relatively militaristic subjects (hawks) were
separated for discussion of hypothetical situations relevant to their value
differences. It was predicted that discussion within the homogeneous communities of doves and hawks would increase the polarization between the two
communities. Contrary to prediction, both communities of subjects shifted to
increased pacifism following discussion. Experiment 2 replicated this attitude
shift and explored informational and normative influence explanations of it.
Evidence indicated that informational mechanisms were operating; support
was not obtained for social comparison processes.
The major empirical generalization arising
from the "risky-shift" literature is that group
interaction tends to enhance choice tendencies initially valued in the subject population
(cf. Pruitt, 1971). Several investigators (e.g.,
Gouge & Fraser, 1972; Moscovici & Zavalloni, 1969) have reported evidence for the
validity of this "group-polarization" hypothesis on attitude measures. In most of these
studies which attempt to extend research on
choice-dilemma items to new dependent measures, the strategy has been to engage subjects in discussion of stimulus materials
which elicit some dominant predisposition,
just as choice-dilemma items have been selected which elicit initial value tendencies in
the risky or the cautious direction.
A second possible strategy for testing the
external validity of the group-polarization
hypothesis is to compose groups of subjects
sharing common value tendencies relevant to
the discussion materials and to contrast their
average discussion-induced response shift with
that of other groups of subjects sharing opposite inclinations. For example, Myers and
Bishop (1970) predicted that discussion
would enhance dominant group values, leading
to increased polarization between homogene1
This research was supported by National Science Foundation Grant GS 2891A#1.
2
Requests for reprints should be sent to David
G. Myers, Department of Psychology, Hope College, Holland, Michigan 49423.
8
Paul J. Bach is now in the graduate program at
Ohio State University.
ously composed groups of high- and lowprejudice high school subjects. As predicted,
discussion of racial-attitude items with others having similar attitudes significantly increased the attitude gap between high- and
low-prejudice groups.
Since there is evidence that informal communication is a significant determinant of
opinions (McGuire, 1969) and that people
tend to be attracted to similar others (Byrne,
1971), there is need for more research on the
question: What effects on attitudes result
from discussion among persons who share
common tendencies? Experiment 1 explores
this question. In an attempt to conceptually
replicate the Myers-Bishop racial-attitude
study, groups of relatively pacifistic and
groups of relatively militaristic subjects were
separated for discussion of hypothetical situations relevant to their value differences. It
was predicted that discussion within the
homogeneous communities of doves and hawks
would increase the polarization between the
two.
EXPERIMENT 1
Method
Subjects. Students of both sexes in two introductory psychology classes participated in the experiment as part of a classroom research demonstration.
One week prior to the experiment, 170 students
completed a criterion questionnaire used to compose
groups for the experiment. Of these, 118 students
were also present to participate in the experiment
the second week.
741
742
DAVID G. MYERS AND PAUL J. BACH
Criterion measure. Pilot testing with a pool of
hypothetical military crises yielded a pool of IS
items, 9 of which were administered as the criterion
measure for identifying doves and hawks and 6 of
which were used as stimulus materials for the experimental discussions. Each of these asked the
subject to role play the position of a presidential
advisor and to indicate his advice by checking five
semantic differential scales. Three of the five semantic differential scales were evaluative and were
used to derive the subject's "pacifism score." The
format is illustrated by one of the discussion items:
Uncontrolled
student
demonstrations
have
plagued Nicaragua for two months. The U.S.
embassy as well as American financial investments now appear threatened. Nicaragua requests U.S. military assistance to quell the
uprising. The President must decide whether to
agree to this request to send troops. In your
advisory capacity, would you judge a proposal
for the deployment of troops as . . . .
Following the item was one of two sets of semantic
differential scales (Set A: valuable-worthless, activepassive, foolish-wise, strong-weak,
positive-negative; Set B: beneficial-harmful, fast-slow, unfairfair, hard-soft, good-bad). Summing across the 27
evaluative responses (9 items X 3 evaluative scales)
yielded a single pacifism score for each subject. The
170 scores thus obtained were rank ordered with
the top 35% being designated doves, the lower 35%
designated hawks, and the middle 30% designated
mixed birds.
Experimental treatment. At the class meeting the
following week, each student was instructed (using
his identification number) to go to one of three
locations on campus. Doves reported to one large
room with movable chairs, hawks to a different
location, and mixed birds and those present who did
not complete the criterion measure to a third location. Because data in the latter condition were contaminated by unclassified subjects, it was our intention not to report the results from this condition.
Dove and hawk room assignments and experimenters
were switched for the second class session to
counterbalance for any room or experimenter effects.
TABLE 1
EXPERIMENT 1: PRE- AND POSTDISCUSSION
PACIFISM SCORES
Hawks
(« = 46)
Doves
(n = 39)
Item
1
2
3
4
5
6
X
* p < .05.
** p < .01.
Pre
Post
Shift
Pre
Post
Shift
1.27
.41
1.16
.95
.88
1.23
.98
1.93
1.41
2.32
1.80
1.97
2.15
1.96
.66**
1.00**
1.16**
.85**
1.09+*
.92**
.98**
-.30
-1.09
-.51
-.74
-.96
-.36
-.67
.34
-.12
.27
.33
.91
.73
.41
.64*
.97**
.78**
1.07**
1.87**
1.09**
1.05**
Between 18 and 25 subjects gathered per room for
each of the two sessions.
Participants in the dove and hawk communities
received identical treatments programmed by identical questionnaires. After first responding to the six
discussion items (with scale sets in ABABAB or
BAB ABA order for the six items), subjects paused
until all were done and then turned to an instruction page entitled "Meeting of the Presidential Advisory Councils."
You have given preliminary advice to the
President by offering your first impression of
each of the proposed actions on the preceding
pages. Of course, in reality, the President's advisors would not have to make their judgments
in isolation, but would instead by actively consulting with each other. In order to simulate
this part of the real political decision making
process, we will now convene some meetings
of the President's advisors so that you can have
an opportunity to briefly talk over some of
these situations with others who must also
advise the President.
The experimenter randomly numbered the subjects into four or five groups with four or five
members each. Subjects then turned forward to a
set of the six 'items presented without the scales for
2j minutes of discussion on each.
Following this was a new instruction page entitled
"Convening of New Advisory Councils." These instructions suggested that to thoroughly pool ideas
and opinions relevant to an important crisis, the
President's advisors engage in repeated conversations.
To simulate this, we would now like to form
new advisory groups, each composed of one
person from each of the current groups. This
will give you an opportunity to pool the ideas
that arose in all the different original advisory
councils. However, you needn't feel bound to
representing your group—feel free to speak for
yourself.
This recomposition was accomplished by having each
group number off and then forming groups of ones,
twos, etc. . . . Subjects turned forward to another
set of the items, again without the response scales,
and again discussed these for 2\ minutes each.
After this, the final instruction page indicated:
Now that you have had an opportunity to pool
ideas within the community of advisors, you are
ready to give the President your final judgment on each of the six proposals. . . . Don't
worry about, or look back at, what you marked
the first time. It is how you feel right now that
we are interested in. In fact, to encourage a
fresh judgment of each proposal we have attached to each situation a different set of scales
than you completed the first time.
Completion of this new set of items finished the
experiment.
DISCUSSION EFFECTS ON MILITARISM-PACIFISM
743
of the situations discussed in Experiment 1.
Results and Discussion
The 18 pre- and postdiscussion evaluative This gave a baseline for evaluating the treatresponses by each subject (6 items X 3 eval- ment effects of three experimental conditions.
uative scales) were averaged and converted to Control subjects also later engaged in two
a —3 (militaristic) to +3 (pacifistic) con- rounds of discussion of each item in an attinuum for ease of interpretation. These indi- tempt to replicate the attitude shift observed
vidual scores were the data for subsequent in Experiment 1. The discussion condition
engaged participants immediately in discusanalyses.
It is first desirable to ascertain whether the sion of the three situations. Their postdiscusdiscussion materials were relevant to the value sion responses can be compared with control
differences measured in the criterion question- pretreatment responses to ascertain whether
naire used to compose the groups. There are the pacifistic shift can also be observed in a
two related indications that the discussion between-groups comparison (without the possibly sensitizing effects of a pretest).
materials were relevant to the group differCurrent theoretical controversy surrounding
ences. First, the correlation between the nineitem criterion measure score and the six-item group-induced shift on choice-dilemma items
prediscussion measure score was .66 (across centers on whether response changes occur
118 persons completing both measures, in- because the subject merely discovers that
cluding mixed birds). The second indication, others share his inclinations more than he had
evident in Table 1, is that as anticipated supposed (social comparison) or because disdoves were more pacifistic in their initial cussion generates persuasive arguments preresponses to the six discussion situations than dominantly favoring the valued alternative
(informational influence). In an attempt to
were hawks.
identify
mechanisms producing the pacifistic
Did the attitude gap between doves and
shift
the
discussion was decomposed into
hawks polarize further following interaction
these
two
components
to define the other two
in their separate communities? Table 1 indiexperimental
conditions.
A social comparison
cates that the doves shifted to increased pacitreatment
merely
exposed
subjects to the acfism after discussion but so did the hawks and
tual
responses
of
the
control
participants.
to an equal extent (F comparing pre- and
Using
choice-dilemma
items,
Myers,
Bach,
postscores = 111.9, df = 1/83, p < .001; F
and
Schreiber
(1974)
found
that
when
this
for the interaction between change score and
treatment was used without requiring comcondition < 1). Furthermore, the shifts were
mitment to a pretest response, a clear social
of striking consistency, occurring at a significomparison
effect was observable. Finally, a
cant level for every item in both conditions.
relevant-arguments
treatment engaged subAlthough not reported here, the mixed bird
jects
in
an
identification
and sharing of argucondition showed precisely the same pattern
ments without any group discussion.
of results.
The third question above, Why did doves
and hawks shift identically in Experiment 1?
EXPERIMENT 2
Although the group polarization hypothe- was examined on a post hoc basis. Although
sis was not confirmed by Experiment 1, the participants were not separated into dove and
hawk communities for the experiment, they
striking character of the results raises three
questions: (a) Can the group-induced shift to were given the nine-item criterion questionnaire to enable later comparisons of doves
pacifism be replicated? (b) Can mechanisms
and hawks in terms of certain informational
responsible for this attitude change be idenand social comparison measures.
tified? (c) Why did the dove and hawk communities shift identically rather than polar- Method
ize? Experiment 2 is addressed to these quesSubjects. The participants were 177 students in
tions.
eight introductory psychology classes. Two classes
The experiment had four conditions. The were randomly assigned to each of the four condicontrol condition elicited responses to three tions and the experiment was conducted in class as a
744
DAVID G. MYERS AND PAUL J. BACH
social psychology demonstration. All participants
began by completing the nine-item criterion measure
used in Experiment 1, with experimental conditions
diverging as indicated below.
Control condition. This condition replicated the
procedures used in Experiment 1 except for minor
variations. Due to time limitations, only Discussion
Items 1, 3, and 5 from Experiment 1 were used
and the set of scales was not varied for any item
(Sets B, A, and B were attached to Items 1, 2, and
3, respectively). Also, following the prediscussion
response to these items, subjects were instructed to
go back over the items and "guess for each scale the
average response of your fellow students here in the
room with you." Finally, two two-minute rounds of
discussion were elicited on each item.
The control condition prediscussion responses to
the three items, not the postdiscussion responses,
provide the baseline for evaluating the effects of the
experimental treatments.
Discussion condition. This condition was identical
to that of the control condition except that immediately after completing the criterion measure, subjects began discussing the situations (presented without the scales as in Experiment 1). Following completion of the posttreatment items, subjects in each
of the experimental conditions also estimated the
average response to each scale by the others present.
Social comparison condition. Following completion of the criterion measure, social comparison
subjects were instructed that in order to simulate
the opinion-sharing process which presidential advisors would experience, they were to study three
new items.
Also, we've indicated the percentage distribution of responses by previous advisors in the
experiment (in some of the other introductory
psych classes that have already participated).
As you can see there is no objective right answer. During this phase of the simulation, while
you are familiarizing yourself with the warmup
materials, you can form your own opinion but
you should not write or mark anything in the
booklet.
Following this instruction page appeared xeroxed
copies of the three items with the distribution of
responses by control subjects indicated and labeled
as "judgments of previous advisors." After "an
opportunity to scrutinize these proposals and the
opinions of other advisors," subjects responded to a
new set of the three items.
Relevant-arguments condition. After completing
the criterion measure, subjects were instructed that
in reality the President does not usually seek
advice on this form, rather he seeks from his
advisors not their opinion as to what he should
do, but their analysis of the pros and cons of
any particular proposal. In order to simulate
this part of the real political decision making
process, we would like to now give you three
more situations. This time play the role of ad-
visor by simply listing under each item any
relevant arguments you can think of for or
against the proposal, as if you were preparing
a brief of all the considerations the President
should be aware of. You are not asked to indicate your opinion about what action should be
taken, just some of the factors that should be
weighed.
After reading an item, subjects were given two
minutes in which to list arguments favoring the
proposed action (using separate boxes for each argument) and (in another column) arguments favoring
the opposite of the proposed action.
Following this argument listing, an assistant who
was naive to the purposes of the experiment allowed
subjects to "pool their ideas by hearing each other's
arguments" to simulate an information-sharing
process.
To save time we will read the listed arguments
of one-third of the class for each of the three
items. Some of these arguments may seem persuasive and convincing, others may seem less
important and less convincing, and some may
appear entirely irrelevant, insignificant, or even
misleading. In any case these arguments should
be helpful in clarifying the situation so that in
the end you can give the President your best
judgment. Please now turn back three pages
to the first of the three items and listen as we
quickly read the thoughts that have been written.
Following this informational exchange, each subject responded to a new set of the three items.
Results and Discussion
As in Experiment 1, the evaluative responses by each subject were averaged (across
three items and three scales) and converted
to a —3 (militaristic) to +3 (pacifistic) continuum.
Before examining treatment effects, it is
first desirable to ascertain whether the classes
participating in the experiment differed on
the dependent measure apart from the variation produced by treatment effects. There are
two indications that they did not. First,
scores on the mean nine-item criterion measure, which preceded the treatment manipulation, were nearly identical for each of the
four conditions (/? = .10). This indicates
that the random assignment of classes to conditions resulted in equivalent initial pacifism
tendencies in each of the four conditions. Second, t tests comparing dependent-measure
scores of the two classes within each condi-
745
DISCUSSION EFFECTS ON MILITARISM-PACIFISM
tion indicated no significant within-condition
variation among classes (all ts < 1).
Can the group-induced skiffs to pacifism be
replicated? Table 2 indicates that the control
condition significantly increased in pacifism
after discussion of the three items (t — 6.83,
df = 48, p < .001). This replicates the shift
found in Experiment 1 using a repeated measures comparison. Is this pacifism shift dependent on the sensitizing effects of a pretest? The control-prediscussion responses provide a baseline for examining the effects of
discussion in a between-groups comparison.
Responses in the discussion condition were
nearly identical to postdiscussion control responses and significantly different from prediscussion control responses (t = 5.06, df =
85, p < .001). In fact, only 2 of the 38 discussion-condition subjects responded less
pacifistically than the control baseline. Thus
the group-induced shift to pacifism is replicated using both a within-group and a between-groups comparison.
Can mechanisms responsible for this attitude change be identified? Why did the dove
and hawk communities of Experiment 1 shift
identically rather than polarize? The relative
contributions of informational and normative
influence in group discussion were examined
by decomposing the discussion into the relevant arguments and social comparison conditions. Examination of Table 2 indicates that
the magnitude of the relevant-arguments
treatment was about one half that of the discussion effect. Statistical comparisons indicate this informational effect to be significant
in comparison with the control baseline (t =
3.36, df = 96, p < .01) but significantly less
than the discussion effect (t = 2.09, df = 85,
p < .05). This finding parallels results obtained by St. Jean (1970) and Vinokur and
Burnstein (1974) indicating that passive exposure to arguments produces a small response shift.
Exposure to the distribution of responses
by control condition subjects produced relatively accurate perception of those responses
by social comparison condition subjects, but
the effect of this treatment on the subjects'
own scores was only marginally significant
(t = 1.94, df — 88, p < .06, for the compari-
TABLE 2
EXPERIMENT 2: MEAN PACIFISM SCORES FOR SELF AND
PERCEIVED OTHER
Condition
«
Own
pacifism
Perceived
other
Ownother
Control
Discussion
Relevant arguments
Social comparison
49
-.30
1.08
.53
.19
-.48
.82
.33
-.53
.18
.26
.19
.72*
3X
49
41
Note. Following discussion, control condition pacifism scores
averaged 1.03.
*t< .01.
son with control scores). Thus, while the
treatment effects provide some evidence of
informational influence, there is only weak
evidence to support a social comparison explanation of the group-induced shift. This is
despite the fact that the social comparison
manipulation exposed subjects to a percentage
distribution of others' responses and not just
to the opinions of four others.
Mechanisms producing the pacifistic shift
may be further clarified by examination of
responses to the informational and social
comparison measures and by post hoc comparison of doves and hawks on these measures.
First, we examined the arguments written
by relevant-arguments condition subjects to
determine whether the pooled information
tended to favor predominantly the pacifistic
choice. Vinokur and Burnstein (1974) performed a similar analysis on choice-dilemma
problems and demonstrated that the mere
proportion of arguments favoring a particular
alternative was highly correlated with the
mean rated persuasiveness of those arguments and with the prediction of a model
based on informational influence concepts. In
the present experiment, 54.4% of the written
arguments were against the proposed military
action and 45.6% supported it (t of deviation
from .50 = 2.27, df - 48, p < .05). Why did
not the distribution of arguments favor the
direction of group shift more decisively? This
may have been due to an implicit experimenter demand for both pro and con arguments. It may also be that, as with choicedilemma items, the percentage of written arguments favoring the shift direction tends to
be an underestimate of the percentage of
spoken arguments favoring that alternative
746
DAVID G. MYERS AND PAUL J. BACH
(Bishop & Myers, in press; Silverthorne,
1971; Stokes, 1971; Vinokur & Burnstein,
1974).
It is also of interest to inquire whether
informational and social comparison measures
predict the same direction of shift for subjects classified as doves and hawks. To accomplish this the 177 subjects were divided
into the upper and lower 35% on the criterion measure, defining doves, hawks, and
mixed birds as in Experiment 1. Comparing
the written arguments of these groups, it was
observed that 60% of the doves' arguments
favored the pacifistic choice compared to 54%
of the hawks' arguments and 49% of the
mixed birds' arguments. Only the dove versus
mixed bird difference was statistically significant (t = 2.61, dj = 31, p < .05). It appears,
then, that the written arguments slightly
favored the direction of shift and that the
informational resources available to doves and
to hawks in Experiment 1 were not sharply
different.
Turning now to the social comparison measure, does shift occur when and only when
subjects tend to perceive others as less in the
direction of group shift than themselves? The
control condition self-other differences afford
the purest examination of this as they are
unconfounded by treatment effects. Table 2
indicates that others are not perceived as significantly less pacifistic than self (f < 1), although the small self-other difference is in the
direction predicted by social comparison explanations. Furthermore, whereas doves in the
control condition tended to perceive others
as slightly less pacifistic than self (mean selfother difference = —.57, f = 1.60), hawks,
if anything, tended to see others as slightly
more pacifistic than self (mean self-other
difference = .20, t for comparison with dove
self-other difference = 1.60). Thus the social
comparison measure does not predict the pacifistic shift evidenced by hawks in Experiment
1.
Further evidence related to a social comparison explanation of the pacifistic shift
comes from examination of the diversity of
control condition scores before and after
discussion. Social comparison theory posits
that group-induced change results when those
relatively low on the valued dimension shift
toward those who embody the value more
strongly. This implies an intrinsic relationship
between group convergence and group shift.
An analysis of pre- and postdiscussion variability was performed at the level of individual
items, so as not to confound between-item
variation. The standard deviation among the
49 control scores was computed for each item.
A comparison of pre- and postdiscussion
standard deviation scores on the three items
indicated that the discussion did not have
homogenizing effects (SD = 1.69 before and
1.76 after discussion). Contrary to social comparison theory, group convergence is evidently
not a necessary component of the causal
mechanisms producing group shift in this experiment. Since implicit group decision making would also have increased homogeneity
among responses, this also casts doubt on any
explanation based on the assumption of an
implicit application of group decision rules
(Davis, 1973).
CONCLUSIONS
Contrary to the prediction for Experiment
1, discussion within homogeneous communities
of doves and hawks did not increase the polarization between the two communities. This
finding suggests caution in extending the
group polarization hypothesis to situations
involving separation and grouping on the
basis of initial attitudes.
The striking discussion-induced shift to
increased pacifism observed in Experiment 1
was replicated in equally striking fashion in
Experiment 2. There is little basis for claiming that this pacifistic shift would generalize
to other populations and other behavioral
and attitudinal measures of pacifism. However, this intriguing finding does demand
explanation and does present a challenge to
group-influence concepts derived from research with choice dilemmas. Support was
not obtained for an attempt at explaining
the pacifistic shift in terms of social comparison dynamics. More support was obtained
for an informational influence explanation of
this group effect. The greater impact of active
discussion than mere passive exposure to arguments is consistent with the contention of
DISCUSSION EFFECTS ON MILITARISM-PACIFISM
Bishop and Myers (in press) that cognitive
rehearsal stimulated by group interaction produces change beyond that elicited by the
mere comprehension of arguments (cognitive
learning).
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