Journal of Personality and Social Psychology
2005, Vol. 88, No. 6, 969 –983

Copyright 2005 by the American Psychological Association
0022-3514/05/$12.00 DOI: 10.1037/0022-3514.88.6.969

Chewing on It Can Chew You Up: Effects of Rumination on Triggered
Displaced Aggression
Brad J. Bushman

Angelica M. Bonacci

University of Michigan

Iowa State University

William C. Pedersen

Eduardo A. Vasquez and Norman Miller

California State University, Long Beach

University of Southern California

Ruminating about a provocation increases the likelihood of displaced aggression following a minor
annoyance (trigger). In Study 1, provoked participants who ruminated for 25 min were more aggressive
toward a fumbling confederate than were distracted participants. Provocation-induced negative affect was
positively related to aggression but only among those who ruminated. Study 2 conceptually replicatedStudy 1 and also found that the more negatively people reacted to the trigger, the more likely the trigger
was to increase displaced aggression. Study 3 replicated the findings of Studies 1 and 2 by using an 8-hr
rumination period. All 3 studies suggest that ruminating about a provocation increases the likelihood thata minor triggering annoyance will increase displaced aggression.
Keywords: displaced aggression, rumination, triggering event

Frank arrives 15 min late to work for the 3rd day in a row. His
angry boss gives him a stern reprimand, stating that the company
has no place for lazy and unreliable workers. On the way to thecafeteria for his morning cup of coffee, Frank keeps thinking about
the reprimand and how much he hates his boss. As he waits in line
to pay, a coworker cuts in front of him. Frank angrily snaps at her
and orders her to the end of the line in an outburst laced withobscenities.
Jill spent weeks preparing a presentation for her college class.
After her presentation, her professor harshly criticizes her performance, stating that she was unprepared and disorganized. For theentire day, Jill silently fumes about her professor’s critical remarks. When she returns to her apartment at the end of the day, Jill
curses at her roommate for leaving dirty dishes in the sink.

Displaced Aggression
Aggression is behavior intended to harm another person. Aggression is direct when an individual is provoked and, in retaliation, inflicts harm against the provoker. Aggression is displacedwhen the target is innocent of any wrongdoing but is simply in thewrong place at the wrong time. Displaced aggression can occur
when a person cannot aggress or is constrained from aggressing
against a source of provocation. To aggress directly against thesource of the initial provocation may be unfeasible because thesource is unavailable (e.g., the provoker has left the situation) or
because the source is an intangible entity (e.g., loud noise, foulodor, hot temperature). Fear of retaliation or punishment from theprovocateur might also constrain direct aggression (Dollard, Doob,
Miller, Mowrer, & Sears, 1939). For example, if the provocateur is
one’s boss, as in the beginning scenario, then one might get fired
for an aggressive response.
Apart from our own work with colleagues (Bushman &Baumeister, 1998; Bushman, Baumeister, & Stack, 1999; Pedersen, Gonzales, & Miller, 2000), virtually no recent experimental
research has examined displaced aggression. Moreover, content
analysis of social psychology textbooks shows that contemporarysocial psychology has largely ignored this concept (MarcusNewhall, Pedersen, Carlson, & Miller, 2000). Despite this apparent
disinterest, meta-analytic results confirm that displaced aggressionis alive and well (Marcus-Newhall et al., 2000). Displaced aggression is a reliable effect that is of moderate magnitude (d⫹ ⫽ 0.55;
see Cohen, 1988).

Brad J. Bushman, Institute for Social Research, University of Michigan;
Angelica M. Bonacci, Department of Psychology, Iowa State University;
William C. Pedersen, Department of Psychology, California State University, Long Beach; Eduardo A. Vasquez and Norman Miller, Department of
Psychology, University of Southern California.
Study 2 was conducted in partial fulfillment of Angelica M. Bonacci’s
master’s degree requirements. Study 1 was supported by a grant to Norman
Miller from the James H. Zumberge fund, University of Southern California. Preparation of this article was facilitated by National Institute on
Alcohol Abuse and Alcoholism Grant R21-AA013343.
Correspondence concerning this article should be addressed to Brad J.
Bushman, Institute for Social Research, University of Michigan, 426
Thompson Street, Ann Arbor, MI 48106, or to Norman Miller, Departmentof Psychology, University of Southern California, Los Angeles, CA 900891061. E-mail: bbushman@umich.edu or nmiller@usc.edu

Triggered Displaced Aggression
In the typical displaced-aggression research paradigm, participants are initially provoked and then allowed to aggress against an
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innocent third party. Such studies, however, do not capture all
instances of displaced aggression. Often, the target of displaced
aggression is not an innocent, nonprovoking individual. Rather, as
illustrated by our opening anecdotes, the target emits a mildly
annoying act, as when the coworker cut in line or the roommate
left dirty dishes in the sink. The term triggered displaced aggression refers to such instances. Following an initial provocation, thetarget commits a minor provocation, the triggering event, which inturn prompts an aggressive response (Dollard, 1938). The initial
provocation and the subsequent triggering event can synergistically combine to elicit a disjunctively augmented aggressive response toward the triggering target. By disjunctively augmented,
we mean that the aggression directed toward the target exceedsthat which is predicted by a tit-for-tat matching rule (Axelrod,
1984). That is, the aggression directed toward the target exceeds
what is expected on the basis of the intensity of the triggering
event or exceeds what is expected by adding the separate
aggression-eliciting effects of the provocation and the triggering
event (Miller & Marcus-Newhall, 1997).
An important caveat is that the intensity of the triggering event
must be minor in comparison with the initial provocation in orderfor such a synergistically interactive aggressive response to occur(Miller & Marcus-Newhall, 1997; Pedersen et al., 2000; Vasquez,
Denson, Pedersen, Stenstrom, & Miller, 2005). Minor triggering
events are more ambiguous with respect to provocation and intentionality than are strong ones (Vasquez et al., 2005). In the absenceof the initial provocation, an individual might judge the triggering
event as nonprovocative and unworthy of an aggressive retaliation.
However, a strong initial provocation might prime individuals toexperience triggering events as more intentional and provoking
and deserving of an aggressive retaliation (Duncan, 1976; Higgins& King, 1981). If the triggering event does not produce an aggressive response in the absence of a strong initial provocation, then it
must be relatively minor in comparison with the initial
provocation.
One problem with the few initial studies on triggered displaced
aggression is that the intensity of the triggering event was at least
as strong as the intensity of the initial provocation (Pedersen et al.,2000). Consequently, the hypothesized interaction between provocation and trigger did not occur. However, two recent studies
confirmed the moderating effect of a minor triggering event on
displaced aggression (Pedersen et al., 2000). For example, in oneof these studies, participants were either provoked or not provokedby an experimenter. Later, they interacted with a confederate who
was either incompetent (trigger) or competent (no trigger). As
expected, participants who were initially provoked displayed more
displaced aggression in the presence of a triggering event than in
its absence. The trigger had no effect on participants who were notprovoked (see also Vasquez et al., 2005).

negative affect. Negative affect, in turn, prompts two different
reactions: fight tendencies, which are associatively linked withaggression, and flight tendencies, which are associatively linked
with fear. If fight tendencies are activated, then aggressive
thoughts, feelings, and behavioral tendencies are also activatedbecause they are part of the same associative network. Similarly,
thoughts, feelings, arousal levels, and behavioral intentions areinterconnected in the general aggression model (GAM; Anderson& Bushman, 2002). For example, angry feelings and increased
arousal levels might bring to mind aggressive thoughts.
Ruminatively based displaced aggression describes acts of displaced aggression that occur long after the initial provocation.
When the temporal gap between the initial provocation and thesubsequent triggering event exceeds 20 min, then displaced aggression is primarily a result of rumination. Miller et al. (2003)
argued that ruminative processes maintain a cognitive representation of the subjective state generated by the initial provocation,even though the initial physiological arousal from that provocation
has dissipated. Rumination facilitates displaced aggression because it maintains the aggression network activated by the initial
provocation.

Triggered Ruminative Aggression
Rumination has been defined as self-focused attention toward
one’s thoughts and feelings (Lyubomirsky & Nolen-Hoeksema,1995). Rumination can also be defined more narrowly as
provocation-focused thought. Ruminative thought can maintainangry feelings (Martin & Tesser, 1989; Rusting & NolenHoeksema, 1998). In previous research, the relationship between
an initial provocation and subsequent displaced aggression wasmediated by how angry people became after experiencing a triggering event (Pedersen et al., 2000).1 Among provoked participants, the triggering event generated angry feelings. These angry
feelings, in turn, prompted an aggressive retaliation against themildly annoying target. Among nonprovoked participants, the triggering event did not augment aggressive behavior. Recall our
opening anecdote in which the college student who was harshly
criticized by her professor and had ruminated about it during the
car ride home subsequently cursed at her messy roommate when
she got home. In parallel, any process that maintains an angrymood after an initial provocation, such as rumination, should
increase triggered displaced aggression. Likewise, any process that
distracts attention away from an angry mood should decrease
triggered displaced aggression.
No prior study has examined whether ruminating about a provocation augments aggressive responding to a mildly annoying

Theoretical Model of Triggered Displaced Aggression
Miller, Pedersen, Earleywine, and Pollack (2003) proposed atheoretical model of triggered displaced aggression that is based, inpart, on Berkowitz’s (1989, 1990, 1993) cognitive neoassociation
model of aggression. Berkowitz posited that aggressive thoughts,
emotions, and behavioral tendencies are linked together in an
associative network. Aversive events (e.g., provocation) prompt

1
Reanalysis of Pedersen et al.’s (2000) data indicated that provoked participants became angrier after experiencing a triggering event than did nonprovoked participants. This finding held true in both Study 1, t(30) ⫽ 1.98,
p ⫽ .06, and Study 2, t(22) ⫽ 2.23, p ⫽ .04, despite differences in how the
provocation and the trigger were operationally defined in the two studies.

RUMINATION AND TRIGGERED DISPLACED AGGRESSION

event that occurs long after an initial provocation.2 We proposethat ruminating about a provocation will increase aggressive responding to a subsequent triggering event. We expected provoked
individuals who were induced to ruminate for an extended period—namely, 25 and 20 min (Studies 1 and 2, respectively) or 8
hr (Study 3)—to exhibit more displaced aggression after a trigger
than those not induced to ruminate.
How does rumination augment aggressive reaction to a triggering event? In keeping with Berkowitz’s (1989, 1990, 1993) cognitive neoassociation model, which ascribes a key aggressioninstigating role to negative affect, our preceding discussion hasemphasized cognitive representations of negative (angry) affect asa critical aggression-inducing component of rumination. By contrast, the GAM (Anderson & Bushman, 2002) emphasizes physiological arousal, affect, attributions, and behavioral intentions asconceptually distinct factors, any or all of which can function
independently to increase aggression. Thus, although rumination isnecessarily cognitive, the GAM implies that it can consist of
cognitive representations and elaborations of any or all four ofthese aggression-inducing antecedents: (a) arousal cognitions—awareness of one’s prior physiological responses to the provocation, (b) affect cognitions—awareness of specific emotions felt at
the time of the provocation, (c) attributions or interpretations
concerning the provocateur’s aggressive act—“he thought I was
stupid,” and (d) behavioral inclinations—thought about specificacts of harm that one wished one had bestowed on the provocateur.
Extending the GAM, to the degree that rumination contains cognitive representations of any or all four of these factors, it willheighten sensitivity and reaction to a mild triggering event, thereby
increasing aggressive responding to it.
Here, however, we cannot systematically explore such details
concerning how rumination produces these effects, nor can we test
the comparative validity of the neoassociationistic versus the
GAM implications regarding the critical mediating components ofrumination. Thus, although we do examine the aggressionmediating role of the rumination-induced augmentation of angry
affect and angry attributions in response to the trigger, we do not
examine the other types of cognitive representations that may beelicited during rumination (i.e., physiological arousal and behavioral intentions) and whose cognitive accessibility is seen by the
GAM as also mediating aggression. Nor do we explore here thetemporal positioning of their occurrence.

Study 1
In typical displaced-aggression paradigms, the temporal gap
between provocation and the displaced-aggression opportunity
rarely, if ever, exceeds 10 min. Research suggests that without
rumination, anger generally dissipates within 10 min (Fridhandler& Averill, 1982; Tyson, 1998). The purpose of Study 1 was to test
whether ruminating about a provocation beyond 10 min would
increase the likelihood of triggered displaced aggression. In thepresence of a triggering event, we expected displaced aggression tobe higher for people induced to ruminate about the provocation
than for those not induced to ruminate. In the absence of a
triggering event, we expected little displaced aggression, regardless of whether people ruminated about the provocation. We also
expected the anger produced by the provocation to increase dis-971

placed aggression but only among people who ruminated about the
provocation.

MethodParticipants and Design
Participants were 42 undergraduate students from the University ofSouthern California (29 women and 13 men) who received extra course
credit for voluntarily serving in a 3 (rumination, distraction, positivemood) ⫻ 2 (trigger, no trigger) between-subjects design.

Procedure
Participants were tested individually. They were told that the researchers
were conducting a three-part study on various cognitive skills. The firstpart ostensibly investigated the effect of music on problem-solving ability.
In reality, it served as the induction of provocation. Each participant
received a list of 15 difficult anagrams (e.g., NVTNIMEREON unscrambled to spell ENVIRONMENT) and was told to solve all of them within 4
min. The participant listened to loud and distracting background music(viz., Stravinsky’s Rites of Spring) while working on the anagrams. After
4 min, the experimenter returned, turned off the music, took the anagram
sheet (ostensibly to grade it), and gave the participant anagram scores froma sample of engineering students who manifestly performed quite well on
the task. A few minutes later, the experimenter returned with the participant’s test “score.” He stated that the participant’s score was below averageas compared with the sample of engineering students. He said that theparticipant’s performance was very poor and that the anagram portion of
the experiment should be done over again. The experimenter then added, inan exasperated and irritated tone, that it would be a waste of his own time
to repeat the test and that they should just proceed to the second part of thestudy. Pedersen et al. (2000, Study 1) have successfully used this procedure
to induce provocation in previous research.
Participants were told that the second part of the study assessed imagination and creativity. They were randomly assigned to one of three groups:
rumination, distraction, or positive mood. Participants in the ruminationand distraction groups were given a packet with a phrase on each page.
They were told to think about each phrase, spend 1 or 2 min writing any
thoughts that came to mind on a pad of paper, and then move on to the next
page of the packet and repeat this same process for 25 min. They were told
not to worry about spelling or grammar. In the rumination condition, thephrases were internally focused. To avoid making participants suspicious,
the phrases did not mention specific emotions (e.g., anger). Examples
included “what kind of a person you are,” “why people treat you the way
they do,” and “how you interact with people.” In the distraction group, thephrases were externally focused. Examples included “the layout of thelocal post office,” “a double-decker bus driving down the street,” and“clouds floating by in the sky.” In previous research, judges rated bothtypes of phrases as affectively neutral (Rusting & Nolen-Hoeksema, 1998).
In the positive mood group, participants recalled a specific time in theirlives when they were very happy and then wrote about it (see KrauthGruber & Ric, 2000, for a similar mood-induction procedure). Participants
were told to focus on specific details of the incident and to describe why
they were happy. When they finished writing about one incident, they were2
We could locate only a single study that has examined the effect ofruminative activity on aggressive behavior. Konecni (1974) found that preventing people from engaging in rumination reduced direct aggression toward
an insulting confederate. No studies, however, have examined the relation
between rumination and displaced or triggered displaced aggression.

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BUSHMAN, BONACCI, PEDERSEN, VASQUEZ, AND MILLER

told to write about another and to continue this process for 25 min. The
positive mood condition served as an additional control.
The experimenter informed participants that the third part of the study
investigated the impact of audio and visual stimuli on problem solving.
Participants watched a video of an undergraduate research assistant who
stated trivia questions aloud and displayed a card with the multiple-choicefoils for each question. Participants answered as many questions as they
could. They were told that the research assistant on the tape had applied fora coveted position as a paid researcher in a faculty member’s lab and thatthe faculty member wanted participants to evaluate applicants. At theconclusion of the tape, the experimenter reentered the room, retrieved eachparticipant’s trivia answer sheet, provided a summary sheet indicating the
average score obtained by a group of engineering students on the same
trivia game from the previous semester, and then left to “score” the test.
Within each of the three groups (i.e., rumination, distraction, and positive mood), participants were randomly assigned to the trigger or theno-trigger group. In the trigger group, the research assistant read the trivia
questions too quickly, mispronounced some of the words and names (e.g.,
Leonardo da Vinci was pronounced Leon Divinsky), and occasionally
mixed up the multiple-choice responses (e.g., presenting the multiplechoice responses to Question 12 after reading Question 9). In addition,
participants were told that they did poorly in comparison with the average
engineering student, but they were not insulted about their performance. In
the no-trigger group, the research assistant read the trivia questions slowly,
made no pronunciation errors, and correctly matched the questions with theappropriate sets of multiple-choice answers. In addition, participants weretold that their score was about the same as that of the engineering students’
average score. Pedersen et al. (2000, Study 1) have successfully used thistrigger manipulation in previous research.
After obtaining feedback from the experimenter about their performanceon the trivia game, participants received a four-page packet containing
dependent measures and manipulation check items. The aggression measure, positioned on the first page, consisted of five items that were rated onan 11-point scale ranging from 1 (strongly agree) to 11 (very strongly
disagree). One item assessed how strongly they recommended the research
assistant for the paid assistantship position. Four other items assessed theirevaluation of the confederate on the following dimensions: likable,
friendly, competent, and intelligent. Aggression is generally defined as any
behavior intended to harm another person (Bushman & Anderson, 2001).
By giving a negative evaluation, participants could harm the research
assistant’s chance to obtain a highly coveted paid job.
The second page of the packet contained the trigger manipulation check
items. Participants gave their general impression of the research assistant’s
performance on the trivia game. Three items assessed the participants’emotional reaction to the assistant’s performance (viz., irritated, happy,
and angered or upset), whereas the remaining four items assessed how well
the research assistant performed the task (viz., read the questions slowly,
spoke clearly, administered the questions efficiently, and read the questions
correctly). Again, all items were rated on an 11-point scale ranging from 1(strongly agree) to 11 (very strongly disagree).
The third page of the packet contained the rumination manipulation
check items. Two items assessed a cognitive response to the rumination
manipulation. Participants rated how often and how strongly they thought
about their performance on the anagram task (viz., the initial provocation)
while performing the imagination and creativity task (viz., the 25-min
assignment that served as the manipulation of rumination). These two items
were rated on a 7-point scale ranging from 1 (not at all) to 7 (very often orvery strongly). The other six items assessed affective responses to therumination manipulation (i.e., angry, grouchy, happy, irritated, pleased,
and sad). They were rated on an 11-point scale ranging from 1 (strongly
agree) to 11 (very strongly disagree).
The fourth page of the packet contained a modified Mood Adjective
Check List (Nowlis, 1965) to report how the participants were affected by

the initial provocation. On an a priori basis, 10 adjectives were used tomeasure provocation-induced negative affect (i.e., angry, defiant, hostile,
disgusted, irritable, scornful, annoyed, loathing, grouchy, and frustrated).
Participants were instructed to describe how they felt after performing theanagram task (viz., the provocation). The items were scored on a 4-point
scale ranging from 0 (definitely did not feel this way) to 3 (definitely did
feel this way). Responses from the 10 items were summed to form acomposite score (Cronbach’s ␣ ⫽ .90). Finally, participants were fully
debriefed.

Results
Preliminary Analyses
Sex differences. There were no main effects or interactions
involving sex for any of the measures. Thus, the data for men andwomen were combined for subsequent analyses.
Statistical assumptions. Tukey’s (1977) box plot was used to
identify extreme outliers, but none were found.
Trigger manipulation checks. To assess the effectiveness ofthe trigger manipulation, participants rated their emotional response to the research assistant’s performance (viz., irritated,
angered or upset, or happy). They also rated the research assistant’s performance on the following dimensions: (a) read thequestions slowly, (b) spoke clearly, (c) administered the questions
efficiently, and (d) read the questions correctly. After the happy
and task performance items were reverse scored, the seven items
were averaged to form a composite score (Cronbach’s ␣ ⫽ .93).
As expected, composite scores were significantly higher in thetrigger group (M ⫽ 7.08, SD ⫽ 1.72) than in the no-trigger group(M ⫽ 3.02, SD ⫽ 1.38), t(40) ⫽ 8.45, p ⬍ .01, d ⫽ 2.60.
A further analysis using this same composite variable assessed
whether the manipulation of rumination differentially affectedparticipants’ reactions to a subsequent triggering event. Among
triggered participants, those in the rumination condition reported amore negative reaction to the triggering event than did those inboth the distraction and positive mood conditions, t(19) ⫽ 2.52,
p ⬍ .05.
Rumination manipulation checks. To assess the effectivenessof the rumination manipulation, participants indicated how often
and how strongly they thought about the anagram task while
completing the imagination and creativity task. Because of theirhigh internal consistency (Cronbach’s ␣ ⫽ .87), the two items
were averaged to form a composite score. Analysis of variance(ANOVA) revealed that the three groups (i.e., rumination, distraction, and positive mood) did not differ on this purely cognitive
measure of rumination, F(2, 38) ⫽ 0.15, p ⬎ .05.
Participants indicated their affective response to the rumination
manipulation (viz., how angry, grouchy, happy, irritated, pleased,
and sad they felt). After the positive adjectives were reverse
scored, the six items were averaged to form a composite negative
affect score (Cronbach’s ␣ ⫽ .88). ANOVA showed a main effectfor group, F(2, 30) ⫽ 4.64, p ⬍ .05. To interpret the main effect,
two orthogonal contrasts were performed. The first contrast
showed that participants in the rumination group experienced morenegative affect while completing the imagination and creativity
task than did those in the distraction and positive mood groups(M ⫽ 5.86, SD ⫽ 1.90, and M ⫽ 3.78, SD ⫽ 1.84), F(1, 30) ⫽9.23, p ⬍ .01, d ⫽ 1.18. The second contrast showed that the

RUMINATION AND TRIGGERED DISPLACED AGGRESSION

distraction and positive mood groups did not differ (M ⫽ 3.88,
SD ⫽ 1.87, and M ⫽ 3.68, SD ⫽ 1.80), F(1, 30) ⫽ 0.06, p ⬎ .05.

Primary Analyses
Aggression. Evaluations of the research assistant measured
displaced aggression (i.e., recommendation of the research assistant for the paid assistantship position and the evaluative ratings ofliking, friendliness, competence, and intelligence). A negativeevaluation would harm the research assistant’s likelihood of obtaining a highly coveted paid assistantship. Scores on the fiveitems were summed (Cronbach’s ␣ ⫽ .86) and analyzed using a 3(rumination, distraction, positive mood) ⫻ 2 (trigger, no trigger)
between-subjects ANOVA.
The analysis revealed a main effect for trigger, F(1, 36) ⫽ 8.79,
p ⬍ .01. This main effect, however, was qualified by a Trigger ⫻Rumination interaction, F(1, 36) ⫽ 3.53, p ⬍ .05 (see Figure 1).
Rumination influenced aggression in the presence of a triggering
event but did not influence aggression in the absence of a triggering event, F(2, 36) ⫽ 3.25, p ⬍ .05, and F(2, 36) ⫽ 0.96, p ⬎ .05,
respectively. In the presence of a triggering event, participants in
the rumination group were more aggressive than were those inboth the distraction and positive mood groups, F(1, 36) ⫽ 6.11,
p ⬍ .05, d ⫽ 0.92. The distraction and positive mood groups did
not differ, F(1, 36) ⫽ 0.39, p ⬎ .05.
Provocation-induced negative affect and aggression. Given
the long temporal gap between the initial provocation and themeasurement of aggression, we expected to find a link between
provocation-induced negative affect (assessed by the Mood Adjective Check List final postmeasure items) and aggression only
among participants induced to ruminate during that time interval.
We did not expect evidence of such a link among participants inthe distraction and positive mood groups.
As we expected, provocation-induced negative affect was associated with aggression among those in the rumination group (r ⫽.56, p ⬍ .05)3 but not among those in the distraction and positive973

mood groups (rs ⫽ ⫺.27 and ⫺.35, respectively, ps ⬎ .20). The
correlation for the rumination group reliably differed from thecorrelations for the distraction and positive mood groups (zs ⫽2.03 and 2.26, ps ⬍ .05). The correlations for the distraction andpositive mood groups did not differ (z ⫽ 0.23, p ⬎ .80). Thus, notonly did rumination augment participants’ negative affect (see therumination manipulation check results), but among those induced
to ruminate, the magnitude of their negative affective reaction to
the provocation was in turn associated with greater aggressive
response to the trigger. Moreover, within the rumination condition,other correlations reflecting intermediate steps in a causal chainthat links provocation-induced negative affect to aggressive responding to the trigger were also significant. Provocation-induced
negative affect correlated with negative reactions to the trigger asassessed by the trigger manipulation check (r ⫽ .64, p ⬍ .05), and,in turn, these negative reactions to the trigger were associated witha stronger aggressive response to it (r ⫽ .70, p ⬍ .01).

Discussion
In Study 1, we examined whether ruminating about a provoking
event increased the displaced aggression elicited by a minor triggering event. As expected, participants induced to ruminate after
being provoked were more aggressive after a minor triggering
event than were those who were distracted or induced to thinkpositively. In the absence of a triggering event, rumination did notintensify displaced aggression.
Consistent with Berkowitz’s (1989, 1990, 1993) model of aggression, provocation-induced negative affect was associated withincreased displaced aggression for participants induced to ruminate but not for those who were distracted or were induced to thinkpositively. Other correlational evidence suggested that within therumination condition, the stronger the provocation-induced negative affect, the more negative was participants’ reaction to thetrigger. And the more negative the reaction to the trigger, the moreaggression it elicited. These data are consistent with a model inwhich (a) rumination that follows a provocation augments negative
affect; (b) cognitive representations of that negative affect in turnprime reactivity to a trigger, thereby augmenting negative reactions to it; and (c) these negative reactions to the trigger in turnaugment aggressive retaliation. By contrast, in the nonrumination
conditions, the minor triggering event was experienced as only
mildly aversive and was not strong enough to elicit an aggressive
response.

Study 2One limitation of Study 1 is that we did not include noprovocation conditions. Previous research has shown that a minor
trigger does not increase aggression in the absence of provocation(Pedersen et al., 2000). Therefore, in Study 1, we assumed thatrumination would not increase triggered displaced aggression in
the absence of provocation. However, such a conclusion cannot be
drawn unless provocation is manipulated in the experimental deFigure 1. Interactive effects of rumination and a triggering event on
aggression (Study 1). Aggression was measured using the evaluation thatparticipants gave an individual for a coveted research assistantship position. Scores could range from 1 to 11, with higher scores indicating a morenegative evaluation. Vertical bars denote plus or minus one standard error.

3
To reduce the impact of outliers, we calculated this association byusing percentage bend correlations instead of Pearson correlations (Wilcox,
1996).

BUSHMAN, BONACCI, PEDERSEN, VASQUEZ, AND MILLER

974

sign. In Study 2, therefore, we included no-provocation conditions.
Additionally, to provide a conceptual replication of Study 1, weused different operational definitions of the key variables inStudy 2.
Study 2 also further investigated the process by which rumination increases displaced aggression (Miller et al., 2003). Correlational evidence from Study 1 suggested that rumination not only
maintains negative affect over time but also increases the chancesthat the triggering event will be experienced more negatively andthereby will increase displaced aggression. Study 2 more explicitly
tested this mediational model. Specifically, we expected that provoked participants who were induced to ruminate about a provocation would experience the triggering event more negatively thanwould those who did not ruminate. In turn, we expected thesenegative reactions to the trigger to mediate displaced aggression.
We expected no such mediation for those not provoked.

MethodParticipants and Design
Participants were 385 undergraduates at Iowa State University (194women and 191 men) who received extra course credit for voluntarily
taking part in a 2 (rumination, distraction) ⫻ 2 (provocation, no provocation) ⫻ 2 (trigger, no trigger) between-subjects design.

Procedure
Participants arrived at the lab under the ruse that they were taking partin an impression formation study with a same-sex partner. They were told
they would engage in several tasks that would help them form an impression of their partner. As a rationale for the displaced-aggression measure,participants were told that one task involved tasting food, which would
give them an idea of the types of food their partner liked. They were givena “food preference form” and told that they and their partner would eachtaste and rate one of the foods on the list. Participants then rated how muchthey liked certain types of food (e.g., dairy food, snack food, seafood, spicyfood). Ratings (e.g., I like spicy food) were made on a 21-point scaleranging from ⫺10 (strongly disagree) to 10 (strongly agree).
The second task ostensibly assessed verbal skills. All participants saw aseries of scrambled letters on a computer screen for 5 s. Participants were
given 7 s to solve the anagram by writing the correct solution on an answer
sheet and by saying the answer aloud over an intercom. Finally, they were
given 5 s to speak into the intercom a first-person sentence that used theword. The experimenter emphasized that participants must loudly andclearly state their solution and sentence.
The actual purpose of the anagram task was to provoke or not provoke
participants. Those in the provocation condition were subjected to three
aggravations. First, they listened to loud and distracting background music(viz., Holst’s Mars, the Bringer of War) while working on the anagrams.
Second, the anagrams were difficult (e.g., DMMPAIUNNEO unscrambled
to spell PANDEMONIUM). Third, the experimenter interrupted and rudely
insulted them three times during the anagram task. After the 4th anagram,the experimenter said, via the intercom, “Look, I can barely hear you. I
need you to speak louder please.” After the 8th anagram, the experimentersaid in a louder and angrier tone, “Hey, I still need you to speak louder
please!” After the 12th anagram, the experimenter said in a loud, frustrated,and exasperated tone, “Look, this is the third time I’ve had to say this!
Can’t you follow directions? Speak louder!” The experimenter’s insults
were prerecorded and played over an intercom system. This provocation
procedure has been successfully used in previous research (e.g., Pedersen
et al., 2000).

Participants in the no-provocation condition had a more pleasant experience during the anagram task. First, although they also listened tobackground music, it was softer and less distracting (viz., Handel’s Water
Music). Second, they were given simpler anagrams to solve (e.g., ESTT for
TEST). Third, the experimenter did not insult them. After the participants
completed the 4th, 8th, and 12th anagrams, the experimenter simply said,“You have just completed the 4th [8th or 12th] anagram,” respectively.
After participants completed the anagrams, the experimenter took theirsolutions to their partner, ostensibly for evaluation. Participants were toldthat the next activity involved writing an essay. Participants in the rumination condition were told that another professor, unrelated to the study,
was interested in learning about participants’ perceptions of the research
process. The other professor was asking students to write an essay about
their experiences as a research participant. Participants were instructed towrite about what they had done from the start of the study until the present
time as well as the thoughts and feelings they had experienced. They werealso told to write about any individuals whom they encountered in the
study and their thoughts and feelings toward those individuals. Note thatthe only individual with whom participants had interacted was the experimenter. Participants were told to spend 20 min writing their essay.
Participants in the distraction condition were also asked to write an essay
for another professor conducting research unrelated to the current study.
The other professor was supposedly studying visual maps and asked
students to write essays about the layout of the college campus. Participants
were instructed to create a mental map of the campus and describe what
they saw. They were to write about the various buildings, the purpose of
the various buildings, the landscape architecture of the campus, and thespatial relations (e.g., location of buildings) on campus. Distracted participants were also told to spend 20 min writing their essay.
After the participants completed their essay, the experimenter returned
with the anagram solution sheet supposedly completed by each participant’s partner. The experimenter instructed participants to examine thesolutions and evaluate their partner’s performance. The ostensible partner
had solved the same list of anagrams that the participant had solved, plus
three more. If the participant had fewer than three incorrect solutions, thenthe partner correctly solved all of the anagrams, which happened 7% of thetime. The evaluation form asked participants to rate their partner’s anagram
performance by using the following items: (a) “Taking into account thedifficulty level of the task, the other participant’s overall performance on
the anagram test seems _____”; (b) “If you had to guess, the concentrationlevel used by the other participant on the anagram task appears to be_____”; and (c) “Based on the limited information I have, it seems that thelikelihood of the other participant performing very well in a class at Iowa
State University that requires good verbal skills is _____.” Ratings weremade on a 21-point scale ranging from ⫺10 (very poor) to 10 (very good).
There was also space for written comments.
After the participants had evaluated their partner, the experimenter
returned with the partner’s evaluation of the participant’s anagram performance. Participants in the trigger condition received scores of ⫺2 foroverall performance, ⫺1 for concentration level, and ⫺1 for success in aclass requiring good verbal skills, along with the following written comment: “Although the task was difficult, I would have thought a college[class standing of the participant; e.g., sophomore] would have performed
better.” Participants in the no-trigger condition received ratings of 2 foroverall performance, 1 for concentration level, and 1 for success in a classrequiring good verbal skills, along with the following written comment:“Although the task was difficult, I thought my partner did a fairly good job
for a college [class standing of the participant].” Thus, the trigger evaluations were slightly negative, whereas the no-trigger evaluations wereslightly positive. This trigger procedure has been successfully used inprevious research (e.g., Pedersen et al., 2000, Study 2).
The next phase of the study served as the displaced-aggression opportunity (Lieberman, Solomon, Greenberg, & McGregor, 1999). After the

RUMINATION AND TRIGGERED DISPLACED AGGRESSION
participants finished reading the evaluation, the experimenter returned withthe partner’s “food preference form.” Participants were told to examine it
and note what types of food their partner did and did not like to eat. They
also were told that they would next sample one of the items on the list. For
all participants, their partner positively rated most of the foods. However,the partner rated spicy foods as ⫺9 on a scale ranging from ⫺10 to 10. The
partner also provided the written comment “I like most of the foods listed
above, but I hate spicy foods.”
The experimenter then returned with a box containing a 3.5-oz (99.22-g)
Dixie cup, a container of hot sauce, a lid, two spoons, and a cup of water.
The hot sauce was a mixture of 5 oz (141.75 g) of Melinda’s original
habanero pepper sauce XXX HOT combined with 12 oz (340.19 g) ofHeinz chili sauce. Participants were told that they were randomly assigned
to eat pretzels and that their partner was randomly assigned to eat hot
sauce. Participants were also told that their partner would decide how many
pretzels they would consume and that they would decide how much hotsauce their partner would consume. It was emphasized that they, and theirpartner, would be required to consume the entire amount of food productthat they were given. Participants then sampled the hot sauce, which wasvery spicy. They were given water to drink if it was too spicy. The
experimenter then instructed them to spoon into the cup as much hot sauce
as they wanted their partner to consume. Participants were also told toplace a lid on the cup so the experimenter did not know how much hotsauce the participants put in the cup. After the participants finished allocating the hot sauce, the experimenter removed their cup and returned
shortly with a cup containing three pretzels for the participants to eat. The
participants then rated how much they liked eating the pretzels.
Participants also rated how they felt about their partner’s evaluation of
their own anagram performance (i.e., the triggering event). We expected
these ratings to mediate the effect of the trigger on displaced aggression forparticipants who ruminated about the provocation. Participants rated how
angry it made them feel, how much it bothered them, whether it was overly
critical, whether it was harsh, and whether it was nasty. Ratings were madeon a 10-point scale ranging from 1 (strongly disagree) to 10 (strongly
agree). Other items were added as fillers. These key items were standardized and summed to yield an overall composite score of how negatively
participants perceived the evaluation (Cronbach’s ␣ ⫽ .88). Higher scoresindicated a more negative reaction to the anagram evaluation. To control
for order effects, half of the participants rated their anagram evaluation
before allocating hot sauce to their partner, whereas the other half allocated
hot sauce to their partner before rating their anagram evaluation. Finally,
the experimenter probed participants for suspicion and debriefed them.

975

Primary Analyses
We used a 2 (provocation, no provocation) ⫻ 2 (rumination,
distraction) ⫻ 2 (trigger, no trigger) ⫻ 2 (participant sex) betweensubjects factorial design to analyze the data. We obtained significant main effects for provocation and trigger and a two-way
Rumination ⫻ Trigger interaction, Fs(1, 331) ⫽ 8.12, 8.67, and4.01, respectively, ps ⬍ .05. However, these lower order effects
were qualified by the predicted three-way Provocation ⫻ Rumination ⫻ Trigger interaction, F(1, 331) ⫽ 4.12, p ⬍ .05. To
interpret the three-way interaction, the two-way interactions between rumination and triggering event were examined separately
for provoked and nonprovoked participants. For provoked participants, the Rumination ⫻ Trigger interaction was significant, F(1,161) ⫽ 7.46, p ⬍ .01. As shown in Figure 2, in the presence of aminor triggering event, participants allocated more hot sauce ifthey had been induced to ruminate than if they were distracted,
t(75) ⫽ 3.21, p ⬍ .01, d ⫽ 0.68. In the absence of a triggering
event, there was no difference in hot sauce allocation between
participants induced to ruminate and participants who were distracted, t(86) ⫽ 0.56, p ⬎ .05, d ⫽ 0.13.
For nonprovoked participants, the Rumination ⫻ Trigger interaction was not significant, F(1, 178) ⫽ 0.07, p ⬎ .05. As shown in
Figure 3, participants induced to ruminate and participants who
were distracted did not differ in how much hot sauce they allocatedto their partner, regardless of whether there was or was not a minor
triggering event, t(83) ⫽ 0.20, p ⬎ .05, d ⫽ 0.04, and t(95) ⫽ 0.59,
p ⬎ .05, d ⫽ 0.14, respectively.
Other effects less central to the hypotheses being tested werealso found. Overall, men were more aggressive than women, F(1,331) ⫽ 5.09, p ⬍ .05, d ⫽ 0.80. There was also a significant
Rumination ⫻ Sex interaction, F(1, 331) ⫽ 5.85, p ⬍ .05. In therumination condition, there were no sex differences in aggression,t(176) ⫽ ⫺0.11, p ⬎ .05, d ⫽ ⫺0.03. In the distraction condition,
men were more aggressive than women, t(167) ⫽ 3.35, p ⬍ .01,
d ⫽ 0.52. Participants’ sex did not interact with trigger or provocation ( ps ⬎ .05).

Results
Preliminary Analyses
Statistical assumptions. Tukey’s (1977) box plot was used to
identify potential outliers in the primary dependent variable—theamount of hot sauce allocated to the ostensible partner. Because
extreme outliers can unduly influence least squares estimates, they
were removed from the data set (Barnett & Lewis, 1978). An
extreme outlier was defined as allocating more than 25 g of hotsauce to the partner. Removing the extreme outliers left a total
sample size of 347 participants (186 men and 161 women). A
Fisher’s exact test showed that the outliers removed did not dependon experimental condition ( p ⬎ .05).
Order effects. The order in which participants completed themeasures did not influence their level of aggression, either alone orinteracting with other variables ( ps ⬎ .05). Thus, the data from thetwo orders were combined for subsequent analyses.

Figure 2. Effects of triggering event and rumination on aggression after
an initial provocation (Study 2). Aggression was measured using thenumber of grams of hot sauce that participants gave a confederate (whohated spicy food) to consume. Vertical bars denote plus or minus one
standard error.

976

BUSHMAN, BONACCI, PEDERSEN, VASQUEZ, AND MILLER

Figure 3. Effects of triggering event and rumination on aggression without an initial provocation (Study 2). Aggression was measured using thenumber of grams of hot sauce that participants gave a confederate (whohated spicy food) to consume. Vertical bars denote plus or minus one
standard error.

Mediation Analyses
Negative reactions to the triggering event were hypothesized tomediate the relationship between the triggering event and displaced aggression among provoked participants who had been
induced to ruminate about the provocation (i.e., the provocation–
rumination condition). For the other three conditions(provocation– distraction, no provocation–rumination, and no
provocation– distraction), no mediation was hypothesized. Mediation analyses were conducted to test these hypotheses by using the
LISREL 8.52 computer program (Jöreskog & Sörbom, 2002).
Table 1 presents the variance– covariance matrices used foranalyses.
For participants in the provocation–rumination condition, acausal path was specified linking trigger (1 ⫽ trigger, 0 ⫽ notrigger) to negative reactions to the trigger. A second path was
specified linking these negative reactions to displaced aggression.
For participants in the other three conditions, a causal path was
specified linking negative trigger reactions to aggression. However, the path between negative reactions to the trigger and aggression was set to 0. We hypothesized that, regardless of condition, a mildly negative trigger would be interpreted morenegatively than a neutral evaluation in all conditions. The proposedmodel exhibited a good fit to the data, ␹2(7, N ⫽ 337) ⫽ 7.19, p ⬎.05; goodness-of-fit index ⫽ .97; comparative fix index ⫽ 1.00,
root-mean-square error ⫽ 0.14. For participants in the
provocation–rumination condition, the path between trigger andnegative reactions to it was positive and significant (␤ ⫽ .46, z ⫽5.48, p ⬍ .05). Also, the path between negative reactions to thetrigger and aggression was positive and significant (␤ ⫽ .37, z ⫽3.44, p ⬍ .05). These results suggest that for provoked participants
who were induced to ruminate about the provocation, a minor
triggering event produced a negative reaction to the trigger, which
in turn increased displaced aggression (see Figure 4).
For the other conditions, the causal paths between trigger andnegative reactions to the trigger were positive and significant. To

examine the effect of constraining the causal paths between negative reactions to the trigger and aggression to 0 for the otherconditions, another model was run in which these paths wereallowed to vary. Allowing the paths to vary did not significantly
improve the fit of the model over the hypothesized model, ␹2(3,N ⫽ 337) ⫽ 2.87, p ⬎ .05. Moreover, the causal paths between
negative reactions to the trigger and displaced aggression were notsignificant ( ps ⬎ .05). This suggests that negative reactions to thetrigger and aggression were not related to each other in the otherconditions.
The mediation analyses provide support for the hypothesizedmodel. However, for provoked participants who ruminated, it ispossible that the triggering event had a direct effect on displaced
aggression. Consequently, we modified the hypothesized model byadding a direct causal path between the trigger and displaced
aggression and treating that path as a free parameter. Inclusion ofthis path, however, did not significantly improve the fit of themodel, ␹2(3, N ⫽ 77) ⫽ 3.41, p ⬎ 05. Moreover, the direct path
between trigger and displaced aggression was not significant (z ⫽1.87, p ⬍ .05).
The mediation observed among participants in the provocation–
rumination condition can be explored by examining the indirect
effects estimate. The indirect effects estimate and its significancetest are based on Sobel’s (1982) method, which divides the indirect
effects estimate by the standard error and compares that value witha standard normal distribution. Because this significance test has
low statistical power, a modified z⬘ distribution was used rather
than a standard normal distribution (MacKinnon, Lockwood, Hoffman, West, & Sheets, 2002). For the hypothesized model, theTable 1
Variance–Covariance Matrices Used for LISREL Mediation
Analyses in Study 2
Measure1

2

3

Provocation-rumination group (n ⫽ 77)
1. Trigger
2. Evaluation
3. Aggression

0.25
1.28
0.78

23.01
7.53

18.36

Provocation-distraction group (n ⫽ 83)
1. Trigger
2. Evaluation
3. Aggression

0.25
0.83
0.15

14.67
1.42

8.15

No provocation-rumination group (n ⫽ 87)
1. Trigger
2. Evaluation
3. Aggression

0.25
0.59
0.17

14.60
1.49

9.36

No provocation-distraction group (n ⫽ 90)
1. Trigger
2. Evaluation
3. Aggression

0.25
1.06
0.09

15.44
0.41

13.77

Note. Variances are on the diagonal, and covariances are below thediagonal.

RUMINATION AND TRIGGERED DISPLACED AGGRESSION

977

Figure 4. Negative reactions to the trigger as a mediator between trigger and displaced aggression for provoked
participants who ruminated (Study 2). *p ⬍ .05.

indirect effect of trigger on displaced aggression via negativeevaluation was significant (␤ ⫽ .20, z⬘ ⫽ 2.91, p ⬍ .05). Moreover, this remained true even after the direct path between trigger
and displaced aggression was added to the model (␤ ⫽ .17, z⬘ ⫽2.97, p ⬍ .05).
Finally, we also examined a model that reversed the causal
sequencing and thereby tested instead whether the aggression
elicited by the trigger mediated participants’ negative reaction to
the triggering event. Analyses revealed that this reversed mediation model was not viable. In the full reversed causal model for the
provocation–rumination group, the path between trigger and aggression was not significant. Moreover, dropping the direct path
between trigger and negative reactions to the trigger reduced the fitof the model, ␹2(3, N ⫽ 77) ⫽ 41. 59, p ⬍ .05, goodness-of-fit
index ⫽ .88. Thus, the data are not consistent with a model thatsees the rumination-induced aggressive responding to the trigger
as causing negative reactions to the trigger. In sum, the mediation
analyses suggest that for provoked participants who ruminatedabout the provocation, their negative reaction to the triggering
event mediated its effect on displaced aggression.

Discussion
Study 2 conceptually replicated the findings of Study 1. Provoked participants who were induced to ruminate engaged in moretriggered displaced aggression than did provoked participants who
did not ruminate. The absence of either an initial provocation or a
triggering event nullified the effect of rumination on displaced
aggression. These results suggest that the triggering event, in itself,
is indeed minor and not severe enough to elicit an aggressive
retaliation.
On the basis of the theoretical model proposed by Miller et al.
(2003), we hypothesized that ruminating about a provocation
maintains an internal state that primes individuals to interpret
triggering events more negatively than warranted and more deserving of an aggressive retaliation. In Study 2, we included ameasure assessing negative reactions to the triggering event, andwe found support for our hypothesis. Among provoked participants who ruminated, their negative reaction to the triggering event
mediated the relationship between the triggering event and displaced aggression. Participants experienced the minor triggering
event negatively (e.g., anger provoking, harsh, and overly critical),and this negative interpretation, in turn, prompted an aggressive
retaliation.
The fact that people who ruminated about the provocationinterpreted the trigger more negatively is related to research on the
hostile attribution bias, in which one tends to perceive ambiguous

actions by others as hostile (e.g., Crick & Dodge, 1994). Numerous
studies have shown a strong relationship between hostile attribution of intent and aggressive behavior among both children andadults (de Castro, Veerman, Koops, Bosch, & Monshouwer, 2002;
Epps & Kendall, 1995). Thus, it appears that ruminating about aprovocation increases the likelihood that people will perceive
minor triggering events in a hostile manner.
One might hypothesize that it was the triggering event itself, notrumination, that prompted displaced aggression. Evidence, however, refutes this alternative explanation. First, under conditions of
no provocation, the presence or absence of a triggering event had
no effect on displaced aggression. This suggests that under normal
circumstances the triggering event in itself is insufficient to prompt
an aggressive retaliation. In addition, the triggering event had noeffect on displaced aggression either among those nonprovoked oramong those both provoked and distracted. Although nonprovoked
and provoked– distracted participants interpreted a minor triggering event negatively, that interpretation was not sufficient enoughto prompt aggression.
Finally, Miller et al. (2003) suggested that the contribution of
rumination to displaced aggression becomes important when alengthy delay separates the initial provocation and the subsequent
triggering event. In Studies 1 and 2, through the use of a 20 –25min delay period, the interval between provocation and trigger
exceeded the 10 –15-min duration over which provocation-induced
arousal typically persists (Fridhandler & Averill, 1982; Tyson,1998). Moreover, this delay substantially exceeded that used in allprior studies of triggered displaced aggression. Yet, it is stillconceivable that some arousal generated by the initial provocation
lingered and this arousal, not rumination, prompted displaced
aggression. If, however, the delay between provocation and trigger
is lengthened substantially beyond a 25-min interval, then it seems
much more likely that ensuing displaced aggression is ruminatively based rather than arousal-based (Miller et al., 2003). Therefore, in Study 3, we extended the delay between provocation andthe triggering event to 8 hr.

Study 3
The goal of Study 3 was to replicate the findings of Studies 1
and 2 by using a considerably longer rumination period (8 hr as
opposed to 20 or 25 min) and using different operational definitions of the key variables. In the presence of a triggering event, we
expected higher levels of displaced aggression among participants
who had been induced to ruminate about the provocation thanamong those who had not been induced to ruminate about the
provocation. In the absence of a triggering event, we expected low

BUSHMAN, BONACCI, PEDERSEN, VASQUEZ, AND MILLER

978levels of displaced aggression regardless of whether participants
were induced to ruminate about the provocation. Finally, because
we showed in Study 2 that in the absence of an initial provocation
an induction of rumination had no aggression-augmenting effect(irrespective of the presence or absence of a trigger), we omitted
no-provocation conditions in Study 3.

MethodParticipants and Design
Participants were 93 undergraduate students from Iowa State University(59 women and 34 men) who served in a 2 (rumination, no rumination) ⫻2 (trigger, no trigger) between-subjects design. Students received extra
course credit in exchange for their voluntary participation.

Procedure
Participants were tested individually, but each was led to believe that heor she would be interacting with two other participants of the samesex— one in the morning and another in the evening. Participants were toldthat the study involved writing essays on controversial topics, solving
anagrams, and competing on a reaction time task. All of the tasks were
presented as ways to obtain information that could be used to form animpression of the “other participants” in the study, which was the ostensible purpose of the study.
First, each participant wrote a one-paragraph essay on abortion, either
prochoice or prolife (whichever the participant supported). Then, theparticipant’s essay was taken and ostensibly shown to the other (nonexistent) participant for evaluation. Meanwhile, the participant evaluated theother participant’s essay, which always disagreed with the attitudinal
position advocated by the participant (e.g., participants who wrote prochoice essays evaluated pro-life essays). To augment credibility, male andfemale handwritten versions of the standard essays were matched to the sexof each participant. A short time later, the experimenter brought back theparticipant’s own essay along with comments ostensibly made by the otherparticipant. All participants received bad evaluations consisting of negative
ratings on organization, originality, writing style, clarity of expression,
persuasiveness of arguments, and overall quality. Individual scale ratings
on these dimensions varied from ⫺10 to ⫺8 on a 21-point scale ranging
from ⫺10 (very poor) to 10 (very good). An added handwritten commentstated, “This is one of the worst essays I have read!” This provocation
procedure has been used successfully in previous research (Bushman,
2002; Bushman & Baumeister, 1998; Bushman, Baumeister, & Phillips,
2001; Bushman et al., 1999; Pedersen et al., 2000).
Participants were assigned randomly to either a rumination or a norumination group. In the rumination group, they were told that theirevening partner would have access to their essay and essay evaluation.
After leaving to photocopy these materials for the participants’ evening
partner, the experimenter returned a few minutes later and said, “Pleasetake your essay and essay evaluation with you so you can think about themduring the day. Also think about what you might write to justify yourposition and explain your essay evaluation to your partner tonight.” In the
no-rumination group, participants were told that their evening partner
would not have access to their essay or essay evaluation. They were told totear up both forms and throw them in the trash.
Exactly 8 hr later, participants returned for the evening session. First,
they completed an anagram task. To minimize frustration, participants
solved the easy anagrams described in Study 2 (e.g., ESTT for TEST).
Then, they evaluated their partner’s anagram performance and were assigned to trigger or no-trigger conditions as implemented in the procedureof Study 2.

The next part of the procedure, presented as a competitive reaction timetask, was based on a paradigm developed by Taylor (1967). Previous
research has established the construct validity of Taylor’s paradigm (e.g.,Anderson & Bushman, 1997; Bernstein, Richardson, & Hammock, 1987;
Giancola & Zeichner, 1995). The ostensible purpose of the reaction timetask was to give the participant an idea of what his or her partner was likein a competitive situation. Each participant was told that he or she and thepartner would have to press a button as fast as possible in response to avisual cue and whoever was slower would receive a blast of noise throughheadphones. For each competitive reaction time trial, the participant was
permitted to set in advance the intensity of the noise to be received if theother person lost the competition. It could vary between 60 dB (Level 1)
and 105 dB (Level 10). A nonaggressive no-noise setting (Level 0) was
also offered. In addition to deciding the intensity, the winner decided theduration of the loser’s suffering, because the duration of the noise depended on how long the winner held down the button. In effect, theparticipant controlled a weapon that could be used to blast the other personwith loud noise if the participant won the competition to react faster.
The reaction time task consisted of 25 trials. As a constant feature in allconditions, the preprogrammed intensity and duration of noise allegedly set
by the other person were steadily increased across blocks of trials. After the
initial trial, the remaining 24 trials were divided into three blocks with 8
trials in each block. The noise durations, allegedly set by the other participant, ranged from 0.25 s to 2.50 s. The average noise intensity andduration set by the confederate were, respectively, 2.50 and 0.63 s on Block1, 5.50 and 1.38 s on Block 2, and 8.50 and 2.47 s on Block 3. The
participant heard noise on half of the trials within each block (randomly
determined). An iMac computer controlled the events in the reaction timetask and recorded the noise levels and durations set by the participant.
After the reaction time task, participants were given a thought-listingtask (Cacioppo & Petty, 1981; Miller & Baron, 1973). They were given 3
min to list whatever they thought about between the morning and evening
sessions. The thought-listing task was used to check the rumination manipulation. In comparison with participants in the no-rumination group,participants in the rumination group were expected to write more about thenegative essay evaluation that they had received. Finally, participants were
fully debriefed.

Results
Preliminary Analyses
Sex differences. There were no main effects or interactions
involving sex for any of the measures. Therefore, we pooled thedata from men and women for all subsequent analyses.
Statistical assumptions. As in Studies 1 and 2, Tukey’s (1977)
box plot was used to identify extreme outliers on the displacedaggression measure. Eight outliers were detected. Fisher’s exact
test revealed that the outliers did not differ across conditions ( p ⬎.05). This left a total of 85 participants (55 women and 30 men) foranalyses.
Rumination manipulation check. Two independent raters, whowere naive to the experimental conditions, counted (a) the numberof words participants listed about the negative essay evaluation
they had received, (b) the number of words that expressed anger
directly against the person who had insulted their essay, and (c) the
total number of words listed. Because the intraclass correlations
between raters were high (⬎.90), the counts for the two raters wereaveraged (Shrout & Fleiss, 1979).
We calculated the proportion of the total number of words listed
that focused on the negative essay evaluation and the proportion ofangry words. As expected, participants in the rumination group

RUMINATION AND TRIGGERED DISPLACED AGGRESSION

thought more about the negative essay evaluation they had received than did those in the no-rumination group (M ⫽ 0.69, SD ⫽0.34, and M ⫽ 0.41, SD ⫽ 0.37, respectively), t(83) ⫽ 3.68, p ⬍.01, d ⫽ 0.81. More than two thirds of the thoughts listed bypeople in the rumination group focused on the negative essay
evaluation they had received, whereas fewer than half of thethoughts listed by people in the no-rumination group focused on
the negative essay evaluation they had received. Similarly, participants in the rumination condition expressed more anger toward
the person who insulted them than did those in the no-ruminationgroup (M ⫽ 0.40, SD ⫽ 0.40, and M ⫽ 0.23, SD ⫽ 0.32,
respectively), t(83) ⫽ 2.17, p ⬍ .04, d ⫽ 0.48. People who
ruminated expressed almost twice as many angry words about theperson who insulted them. Thus, it appears that the rumination
manipulation was effective. For example, a participant in therumination group wrote that she thought the evaluation was a“joke” and that her partner was “overly critical” and not “openminded.” In contrast, a participant in the no-rumination groupwrote that he thought about such things as “Christmas . . . e-mail. . . my mom” while making no mention of the essay.

Primary Analyses
The intensity and duration of noise that participants set for theirevening partner were positively correlated (r ⫽ .47, p ⬍ .0001).
The pattern of results obtained for the two aggression measures
also was similar. Consequently, following the procedure of previous research (e.g., Bushman, 2002; Bushman & Baumeister, 1998;
Bushman et al., 1999, 2001), noise intensity and noise duration
were standardized and summed to obtain a more reliable measureof aggression.
We were interested only in the intensity and duration of noisethat participants set for the “other participant” on the first trial of
the competitive reaction time task. After the first trial, aggression
converged on what people believed the other person had done (i.e.,
tit-for-tat responding). This is consistent with many other findingsthat confirm the importance of reciprocation norms in determining
levels of aggressive behavior (e.g., Bushman, 2002; Bushman &Baumeister, 1998; Bushman et al., 1999, 2001).
As expected, we obtained a significant Rumination ⫻ Trigger
interaction for aggression on the first trial of the competitive
reaction time task, F(1, 81) ⫽ 4.30, p ⬍ .05, MSE ⫽ 0.97 (seeFigure 5). In the presence of a triggering event, those induced toruminate about the negative evaluation of their essay were significantly more aggressive than those not induced to ruminate,t(81) ⫽ 2.17, p ⬍ .04, d ⫽ 0.48. In the absence of a triggering
event, rumination did not influence aggression, t(81) ⫽ 0.72, p ⬎.05, d ⫽ 0.16. After the first trial, the noise levels set by theparticipant matched those set by the “partner” regardless of experimental condition.

Discussion
The key findings in Study 3 conceptually replicated those from
Studies 1 and 2 but in the context of a much longer rumination
period (8 hr vs. 20 or 25 min). Participants induced to ruminate
about the provocation (by telling them that their evening partner
would have access to their essay and evaluation) exhibited more

979

Figure 5. Interactive effects of rumination and a triggering event on
aggression (Study 3). Aggression is the sum of standardized scores fornoise intensity and noise duration. Vertical bars denote plus or minus one
standard error.

triggered displaced aggression than did those who were not induced to ruminate about the provocation. Miller et al. (2003)
argued that arousal-based explanations of displaced aggression
become less plausible as the delay between the initial provocationand the minor triggering event increases because the arousal generated by the initial provocation dissipates. However, by ruminating about a provocation, an aggressive internal state can be maintained over an extended period of time. The 8-hr delay used inStudy 3 provides even stronger evidence in support of a ruminatively based explanation of displaced aggression. Any arousal
generated by the initial provocation would have dissipated after
8 hr.
A second difference between the first two studies and Study 3
concerns the nature of the control conditions. In Study 1, therumination condition was compared with both distraction andpositive mood conditions. Study 2 again compared the rumination
condition with a distraction condition. Thus, in both of thesestudies, the source of the difference between rumination and comparison conditions was ambiguous because of the absence of a true
no-treatment control condition. Although we have argued thatrumination increases aggression, a plausible alternative interpretation is that distraction (or positive mood) decreases aggression. By
contrast, the rumination condition in Study 3 was compared witha true no-treatment control condition. Of course, it is likely thatevents over the course of the 8-hr interval between the provocationand the trigger may well have been distracting. Nevertheless,participants in the control condition received no explicit instruction or task that functioned to distract them immediately after
receipt of the provocation. In this sense, there is no interpretative
ambiguity in Study 3 about the source of difference between therumination and control conditions.
Study 3, which used new operational definitions of provocation,
trigger, rumination, and aggression, replicated Studies 1 and 2.
This consistency under different operationalizations of the key
variables illustrates the robustness of triggered ruminative
aggression.

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BUSHMAN, BONACCI, PEDERSEN, VASQUEZ, AND MILLER

General Discussion
The three studies presented here provide evidence for ruminatively based triggered displaced aggression. In all three studies,
provoked participants who were induced to ruminate displayed
more displaced aggression after a mildly annoying triggering event
than did those who did not ruminate. Rumination appears toaugment triggered displaced aggression by maintaining an aggressive internal state. A provocation, such as an insult, increases
negative affect and primes aggression-related thoughts, feelings,
and behavior tendencies. This aggressive internal state, in turn,influences how individuals perceive and react to subsequent events(Berkowitz, 1993; Miller et al., 2003). Thus, a mildly annoying
event is perceived as highly aversive and deserving of an aggressive response. If provocation-induced negative affect, however, isallowed to dissipate, the subsequent mildly annoying event isperceived as trivial and is easily dismissed.
The purpose of the current studies was to examine situations inwhich the temporal gap between an initial provocation and asubsequent triggering event exceeds the 10 min in which arousalbased explanations of displaced aggression are likely. Typically,
negative affective states last approximately 10 min (Fridhandler &Averill, 1982; Tyson, 1998). Because previous displacedaggression studies have never extended the time period between
the provocation and the trigger beyond 10 min, the persistence ofarousal generated by the initial provocation can reasonably explainthese empirical findings.
In these three studies, however, triggered displaced-aggression
effects were demonstrated over a longer time gap (viz., 25 min in
Study 1, 20 min in Study 2, and 8 hr in Study 3), making an
arousal-based explanation highly unlikely. Under temporal delaysof these durations, ruminatively based explanations seem more
appropriate. Thus, our studies have an applied significance in thatrumination can explain a large number of instances of real-life
displaced aggression in which the aggressive act might occur hours
after an initial provocation.
Studies 1 and 2 show that ruminating about a provocation
maintains an aggressive internal state that disposes an individual
toward later displaced aggression. People who ruminate about aprovocation experience more negative affect in response to aminor triggering event. Negative affect, in turn, increases aggressive retaliation. These mediational effects, resting on the negative
affect produced by the provocation (Study 1) and on negative
reactions to the triggering event (Study 2), are consistent with
Berkowitz’s (1989, 1990, 1993) cognitive neoassociationistic
model of aggressive behavior, which posits a key mediational rolefor negative affect.
Have we fully isolated the key internal state that accounts for theaggression-augmenting effect of rumination? Obviously, we havenot. For instance, although the augmented negative reactions to thetrigger functioned to mediate the aggression-increasing effect ofrumination in Study 2, note that the items comprising this mediational measure appear to tap two distinct dimensions of theGAM—negative affect and hostile attributions. Specifically, twoitems assessed affect (participants rated how angry the trigger
made them and how much it bothered them), whereas the remaining items assessed evaluation-based attributions about the ostensible partner (overly critical, harsh, and nasty). In light of the highalpha among these two sets of items (.88), it made empirical sense
to analyze them as a single composite. Note also, however, thathigh correlations among the conceptually distinct antecedents ofaggression are not inconsistent with the GAM. Moreover, as
previously indicated, negative affect and negative reactions to thetriggering partner are not the only potential mediational variablesof interest. As noted, we did not measure other relevant components of the GAM that are also postulated to mediate aggressive
responding, such as physiological arousal level and behavioral
intentions. Although a thorough analysis of the processes that
underlie rumination effects was beyond the scope of this set ofexperiments, future research on the relation between rumination
and aggression will need to address this mediational issue more
analytically. Not only might some of the routes to aggression
routinely postulated by the GAM be more readily or strongly
activated by rumination than others, but different means of inducing rumination might also have distinct effects. For instance,
self-focused inductions of rumination (e.g., that used in Study 1),
which turn attention inward, might be expected to particularly
augment the accessibility of cognitive representations of the physiological arousal induced by an initial provocation. By contrast,
provocation-focused inductions of rumination (e.g., that used inStudy 3), which give the actor an external orientation, might be
expected to particularly augment cognitive representations ofimagined or intended aggressive actions toward the provocateur.

The Relationship Between Ruminatively Based Displaced
Aggression and Excitation Transfer Theory
We suggest that the results of the current set of studies are best
understood by using a ruminatively based explanation of displaced
aggression. One might argue, however, that our theoretical analysis of triggered displaced aggression appears to share general
conceptual similarities with excitation transfer theory (Zillmann,
1971, 1979) and that the latter theory can explain our findings. In
excitation transfer theory, a provocation is combined with a manipulation of arousal such as noise, an erotic film, or physicalexercise (e.g., Cantor, Zillmann, & Einsiedel, 1978; Donnerstein &Wilson, 1976; Zillmann, Katcher, & Milavsky, 1972).4 At firstglance, such manipulations of arousal correspond in some sense towhat we have called a triggering event. According to excitationtransfer theory, physiological arousal produced by an event does
not dissipate instantly. If two arousing events are separated by ashort amount of time, some of the arousal caused by the first event
may transfer (or be misattributed) to the second event. For example, if the second event is related to anger, then the additionalarousal lingering from the first event (e.g., exercise) should makethe person even angrier. The misattribution of arousal may occur
because the source of the arousal is ambiguous. Individuals do notrealize that the arousal that is generated by the initial event will
4
The manner in which excitation transfer experiments operationalized
arousal is as follows (in order of most to least frequent): violent/aggressive
films: 24; sexually arousing pictures: 8; erotic films: 6; erotic passages(written): 5; exercise: 4; drugs: 4; sports films: 3; noise/tones: 3; happy
films: 2; unpleasant films: 1; exciting, nonviolent films: 1; hostile news
broadcast: 1; arousing imagery (imagine a scene): 1; aggressive passages:
1; and pain cues from target: 1.

RUMINATION AND TRIGGERED DISPLACED AGGRESSION

linger and thus assume their aroused state was caused by thesecond, more proximal, event.
There are four important differences, however, between these
two bodies of research. First, excitation transfer studies mainly (ifnot exclusively) examine direct aggression against the original
provocateur, whereas the current studies examined displaced
aggression.
Second, the triggering event in our studies was deliberately
designed to be trivial and very low in its arousal qualities. By
contrast, the erotica or strenuous physical exercise typically usedin excitation transfer research characteristically elicits moderate tohigh levels of arousal.
Third, excitation transfer theory posits that if the source of thephysiological arousal generated by the first event is salient, thelikelihood of the transfer of that excitation to the second event isunlikely. For example, if an individual exercises vigorously and isthen provoked, and believes that the arousal is due to the exercise,the person is unlikely to misattribute the arousal to the provocation. In our Studies 2 and 3, we manipulated rumination by having
participants specifically think about the initial provocation, thereby
making it highly salient. According to excitation transfer theory,
ruminating participants should therefore engage in less displaced
aggression because the source of their arousal is highly salient.
However, the results of all three studies show the opposite pattern—participants who ruminated about the initial provocation
engaged in more displaced aggression than participants who did
not ruminate. One might argue instead that both the initial provocation and the subsequent trigger are given the same label by theparticipant (viz., a provoking event). This argument, however, is
not a strong one. The initial provocation and the subsequent
triggering event in our studies not only were qualitatively distinct
but also were delivered by two separate people who were functioning in two distinct roles. The salience-inducing effect of therumination induction used in Studies 2 and 3 is only likely to makethis distinction even more evident to participants.
Fourth, the current studies investigated situations with a longtemporal delay between the provocation and the triggering event.
To our knowledge, no excitation transfer studies contain a temporal delay between the provocation and the arousing event thatexceeds the 5- or 10-min period for which a state of arousal
ordinarily persists.5 Thus, we argue that an underlying cognitive
process, specifically rumination, is driving the triggered displacedaggression effects.

Limitations and Future Directions
The current studies, like all studies, have limitations. Some may
question whether displaced aggression can accurately be assessedin a laboratory setting. For example, one may question whether
giving a negative performance evaluation or blasting a partner withwhite noise parallels snapping at a coworker or cursing a roommate. Meta-analytic work, however, suggests that most laboratory
measures of aggression appear to assess the same underlying
construct (Carlson, Marcus-Newhall, & Miller, 1989). Also, findings from laboratory studies of aggression parallel findings fromreal-life studies of aggression (Anderson & Bushman, 1997).
Our results suggest that ruminating about a provocation increases the likelihood of triggered displaced aggression. To facil-

981

itate ruminatively based displaced aggression, we induced participants to engage in internally focused thinking or thought about the
provocation. Other situational factors, however, might also influence ruminatively based displaced aggression, such as the strengthof the provocation and the importance of the goal the person isblocked from achieving. Another limitation of our three studies isthat we did not include any measures of physiological arousal. We
argue that with a substantial delay (viz., longer than 20 min),arousal directly generated by the initial provocation dissipates
before the subsequent triggering event. However, we do not haveany physiological data to support such a claim. Moreover, it ispossible that ruminating about a provocation might elicit not only
cognitive representations of the prior physiological arousal produced by the provocation, but additionally, it might maintain orreinstate the physiological arousal generated by the initial provocation. Alternatively, or additionally, it might induce stronger
physiological arousal reactions to the trigger, which, in turn, might
increase its aggression-eliciting effects.
Finally, certain personality factors might serve as moderators.
There is considerable evidence suggesting that some individuals
are more prone to rumination than others and, in turn, are more
likely to behave aggressively (e.g., Caprara, 1986; Caprara, Barbaranelli, Colombo, Politi, & Valerio, 1995; Caprara, Barbaranelli,& Comrey, 1992; Caprara, Cinanni, & Mazzotti, 1989; Caprara,
Gargaro, Pastorelli, & Prezza, 1987; Caprara, Mazzotti, Zelli,Coluzzi, & Renzi, 1985; Collins & Bell, 1997). However, no
studies to date have examined how dispositional rumination isrelated to triggered displaced aggression. One might hypothesizethat individuals already prone to rumination might show heightened displaced aggression when induced to ruminate.

Conclusion
The three studies presented here support a ruminatively based
explanation of triggered displaced aggression. They provide the5
One excitation transfer study had an 8-day delay between the provocation and the opportunity to aggress (Bryant & Zillmann, 1979). Physiological arousal from the provocation certainly could not have affected theaggression opportunity in this case. It is important to note, however, thatthe temporal lag in that experiment does not correspond to the location of
the temporal delay in the current set of studies. Consistent with otherexcitation transfer studies, the delay between the arousing event and the
provocation in Bryant and Zillmann’s (1979) study was short—less than 5
min. The 8-day delay is between the provocation and the aggression
opportunity. In Bryant and Zillmann’s study, residual arousal from the firstevent (exercise?) could have been attributed to the provocation that occurred shortly thereafter. When given the opportunity to aggress against theoriginal provoker 8 days later, participants may have retaliated against that
person. This long delayed effect could be due to a ruminative process, suchas those described in our studies. Such a conclusion is speculative, however, considering Bryant and Zillmann did not provide data to support sucha claim. Our delayed studies do not parallel the delayed paradigm used by
Bryant and Zillmann. The delay in the current studies occurred between theinitial provocation and the subsequent triggering event. The triggering
event was immediately followed by the displaced-aggression opportunity.
An excitation transfer explanation seems unlikely because the long delay
between the provocation and the triggering event likely dissipated any
lingering physiological arousal, especially when the delay was 8 hr.

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BUSHMAN, BONACCI, PEDERSEN, VASQUEZ, AND MILLER

first explicit evidence linking ruminative activity to aggressive
behavior, not just angry affect. Moreover, the studies are high inecological validity. In real life, instances of displaced aggression
often occur long after the initial provocation. Our studies clearlyshow that rumination is a factor that can maintain an aggressiveinternal state over an extended period of time.
Individuals undoubtedly face many provocations that makethem angry. Often, retaliation against the provocateur is not possible. For example, bosses frequently reprimand employees, who
passively accept the criticism in order to keep their jobs. Nevertheless, such provocation still makes individuals angry. It can
prompt subsequent aggression against someone who is mildly
annoying but not highly deserving of an aggressive attack. How
individuals focus their attention after a provocation affects how
they will behave toward others. If individuals choose to focus on
their bad mood and the provocation that elicited it, they may
unfairly lash out against innocent others. If, instead, they choose to
let their negative mood dissipate and focus on other events, they
are less likely to lash out. Rather than “chewing on” the tyrannicalboss, perhaps individuals should “chew on” what they want forlunch.

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Received May 12, 2004
Revision received November 4, 2004
Accepted November 19, 2004 䡲

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