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Individual differences and measures of aggression in laboratory studies
Person. individ. 01% Vol. 8, No. 6, pp. 885-893, Printed in Great Britain. All rights reserved
1987 Copyright
0
0191s8869/87 1987 Pergamon
INDIVIDUAL DIFFERENCES AND MEASURES AGGRESSION IN LABORATORY STUDIES G.
$3.00 + 0.00
JournalsLtd
OF
V. CAPRARA, T. GARGARO, C. PASTORELLI, M. PREZZA, P. RENZI and A. ZELLI
Dipartimento di Psicologia, Universith degh Studi di Roma “La Sapienza”, 00185 Italy (Received
19 December
Via degli Apuli S-Rome,
1986)
Summary-After inducing hostility toward a confederate by threatening subjects’ self-esteem, subjects were then given the opportunity either to deliver shocks (Experiment I) or to withhold rewards (Experiment 2) from their confederate. Physiological measures were taken prior to the hostility induction, shortly after the induction and, finally, after the opportunity to aggress. Measures of individual differences relating to aggressive behavior were also considered. While the experimental manipulation was the best predictor in the ‘withholding rewards’ condition, measures of dissipation-rumination tendencies and emotional vulnerability were the best predictors in the ‘shock administration’ condition. In both conditions, systolic blood pressure seemed to reflect differences in arousal as a function of the hostility induction procedures, while subjects in the withhold rewards procedure also showed a decrease in systolic pressure after having an opportunity to aggress toward the confederate. It was concluded that not only is the withholding of rewards a more ethically acceptable procedure than shock administration, but it is also more likely to reflect experimental rather than individual difference affects.
INTRODUCTION
The present study addressed three main issues of experimental research on human aggression related, respectively, to the role of individual differences in personality characteristics, to the use of physiological indices and to the methods used to instigate and to measure aggression in laboratory studies. The influence of personality on aggression: Irritability, emotional susceptibility and dissipationrumination
As noted elsewhere (Caprara, Renzi, D’Augello, D’Imperio, Rielli and Travaglia, 1985a), there has been increased attention in recent years to the role of stable personality characteristics in mediating cognitive and emotional aspects of aggressive behavior. In particular, where temperament or personality constructs and observable behaviors can be related in a meaningful theoretical network, the use of both individual differences and experimental approaches may provide the means to develop a more comprehensive theory, encompassing both person and situation variables. Accordingly, a program of research has been initiated which has identified irritability and emotional susceptibility as personality constructs particularly suited to the study of reactive or impulsive aggression (Berkowitz, 1974; Caprara, Cinanni, D’Imperio, Passerini, Renzi and Travaglia, 198%). Irritability is defined as the tendency to react impulsively, controversially, or rudely to the slightest provocation or disagreement. Emotional susceptibility is defined as the tendency to experience feelings of discomfort, helplessness, inadequacy and vulnerability. While irritability manifests itself as the tendency to behave offensively, emotional susceptibility is reflected in the tendency to be defensive. Both constructs are related to one’s capacity or incapacity to dominate and maintain full emotional control when frustrated, to dominate one’s own reactions when exposed to various sources of stress, failure and provocation, and to overcome excitement and react adequately in imagined or real situations of danger, threat or attack. Both constructs are assumed to reflect a tendency to overreact emotionally to events that are perceived as frustrating, as well as to perceive events as frustrating. PA.10
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These constructs derive from the literature on the links between frustration, emotion, and aggression (Zillmann, 1979; Averill, 1982) and were developed by an empirical analysis which has led to the construction of two scales showing common latent structure, despite efforts in creating unifactorial solutions and despite obvious differences in the items and related behaviors. For example, the 30-item Irritability scale contains items such as: “I think I am rather touchy”; “Sometimes I shout, hit, kick and let off steam”; while the 40-item Emotional Susceptibility scale has items such as: “Fear of failure worries me more than necessary”; “Sometimes I feel on edge”. As indicators of tolerance to frustration, both constructs appear particularly suited to explore the frustration-aggression hypothesis (Dollard, Doob, Miller, Mowrer and Sears, 1939) and its derived hypotheses concerning forms of aggression in which excitatory and involuntary components are likely to play a major role (Berkowitz, 1983; Zillmann, 1979, 1983). In a number of studies using a slightly modified version of the tradition Buss (1961) aggression machine paradigm, highly irritable subjects and highly emotionally susceptible subjects selected, as was expected, higher levels of shock respectively than low irritable subjects and low emotionally susceptible subjects, particularly when previously provoked (Caprara, Renzi, Alcini, D’Imperio and Travaglia, 1983~). Similar findings have been replicated in studies aimed at exploring effects on subsequent aggression of interpolating between a self-esteem provocation and the opportunity to aggress either exposure to aggression eliciting cues such as slides portraying weapons (Caprara, Renzi, Alcini, D’Imperio and Travaglia, 1984a; Caprara, Renzi, Amolini, D’Imperio and Travaglia, 1984b) or physical exercise which increases sympathetic arousal (Caprara et al., 1986a). In all these experiments either irritability or emotional susceptibility, as well as their interaction with self-esteem provocation, were found to account for a substantial portion of the non-random variance with respect to the intensity of subsequent aggression. In contrast, a rather different picture resulted in experiments where the opportunity to aggress did not immediately follow the self-esteem provocation or where other activities able to elicit, maintain, or increase subsequent aggression were not interpolated between the self-esteem provocation and the opportunity to aggress. The passing of time by itself practically eliminated the effect elicited in prior experiments due to the self-esteem provocation and considerably decreased the role of individual differences (Caprara, Conte, Gennaro and Renzi, 1983b; Renzi, Caprara, Crudele, Galante and Giannone, 1984). Consequently, the importance of processes occurring during the time between instigation and expression, such as the cognitive processes which store the experience of provocation and the desire for retaliation, become questions for more serious investigation. In this regard Konecni (1975) has reported on the effects of dissipation and rumination in altering aggressive conduct as a function of the lapse of time separating the instigation to aggress and the moment in which aggression occurs. Since dissipation and rumination might be considered as opposite ends of a single dimension of behavior, they might be also considered as opposite manifestations along a similar continuum of a personality construct characterized, at one end, by an inclination toward rapid dissipation and minimal rumination and, at the other end, by an inclination toward slow dissipation and prolonged rumination. Thus, with the passage of time, ‘dissipators’ would be expected to get over quickly any ill feelings or desire to retaliate, while ‘ruminators’ would be expected to maintain or even increase their desire for vengeance. Accordingly, a new scale has been generated whose psychometric characteristics appear very satisfactory for both the Italian and English version. Sample items of the 20-item dissipationrumination scale are: “It takes many years for me to get rid of a grudge”; “I do not forgive easily once I am offended” (Caprara, 1986). This new scale has proved to be a valid indicator of hostility in experiments in which subjects, after having been threatened in their self-esteem by a confederate, had the opportunity to retaliate against their provoker immediately, 24 hours after provocation, and a week after provocation (Caprara, Coluzzi, Mazzotti, Renzi and Zelli, 1985a; Caprara, Renzi, Mazzotti, Pastorelli and Zelli, 1985b). In these experiments the various personality measures accounted for a substantial part of the non-random variance in levels of administered shocks and contributed to the elaboration of better articulated hypotheses.
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Physiological measures in aggression research
Physiological indices such as systolic and diastolic blood pressure, heart rate, skin conductance and finger temperature have been commonly used-as dependent measures in aggression research. As recently reviewed by Konecni (1984), the main tendency “has been to use them as auxiliary measures, in conjunction with the behavioral ones or, more importantly, as a means of scaling the impact and/or the time course of certain (especially arousal related) experimental variables” (p. 20). Findings are often contradictory and difficult to interpret due to a number of methodological problems related to physiological measures and their statistical analysis, as well as because of a number of theoretical problems related to the meaning and value of physiologial measures in research on aggression. While blood pressure and heart rate changes have frequently been associated with various aggression eliciting cues and aggressive reactions, there is no common pattern or trend among the different indices and a great intraindividual variability is noticed. We are not aware of any study in which physiological indices used as moderator variables or predictors have resulted in a significant role with respect to aggressive behavior. It is likely that most of the methodological problems indicated above would occur also in any case where individual differences in physiological reactions to various aggression eliciting cues or various forms of expression of aggression were examined as antecedent processes rather than as mere correlates of aggressive behavior. Yet, we believe that this direction of research should deserve more attention than it has received so far. Methods used to instigate and measure aggression
As noted elsewhere (Caprara, Passerini, Pastorelli, Renzi and Zelli, 1986b) laboratory studies of aggression are faced with a number of serious methodological problems. Besides the obvious question of the degree to which the measures employed are subject to such experimental artifacts as demand cues and evaluation apprehension, there is uncertainty regarding the external validity of the aggression measures and the unstandardized nature of many of the experimental manipulations. In particular, most of the criticism regarding the Buss aggression machine paradigm has consisted of two types: first, real life aggressors rarely, if ever, attack by giving electric shocks or blasts of unpleasant noise; second, it is an ethically suspect procedure which encourages experimental subjects to inflict physical harm and/or to believe they are to inflict physical harm on another person. While Berkowitz and Donnerstein (1983) have answered the first objection by pointing out that it is the meaning the subjects give their actions that determines whether this behavior is aggressive or not, their answer paradoxically reinforces the validity of the concern expressed through the second objection. In particular, the concern over long-lasting and negative effects of inducing someone to hurt another person is reinforced by the occurrence of guilt and/or aggressive anxiety which is often found in association with the delivery of noxious stimulation. To answer both objections, a new laboratory procedure was developed to operationalize aggression in a different manner than in the original Buss procedure. In Buss’s original procedure, subjects selected levels of noxious stimulation to deliver to a confederate in order to communicate mistakes in a learning or extrasensory perception task. Responses greater than the lowest level noxious stimulation were regarded as aggressive. In the current revised procedure, using the same response machine, subjects select rewards to communicate the correct responses to a confederate and selections other than the maximum possible reward are regarded as aggressive. The injury in the revised method is relatively subtle and consists of depriving the other individual of the maximum amount of rewards, with no personal advantage, rather than apparently harming the subjects physically, as in Buss’s procedure. The first study in which the two procedures have been compared confirms the validity of the new procedure and recommends it as a more convenient procedure to minimize subjects’ distorting reactions due to aggression anxiety or evaluation apprehension and to minimize ethical concerns (Caprara et al., 1986b). AIM
OF THE
CONTRIBUTION
Two experiments were conceived in which the self-esteem threat manipulation used in previous experiments (Caprara et al., 1985a, 1986b) was used to instigate aggression. Measures of irritability,
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emotional instability, emotional vulnerability and dissipation-rumination were obtained for all subjects prior to the experiment. Emotional instability and emotional vulnerability scales resulted from a revision of the original emotional susceptibility scale (Caprara, Borgogni, Cinanni, Di Giandomenico and Passerini, 1985d). Systolic and diastolic blood pressure and heart rate were also taken, the first prior to the experiment, next after the self-esteem threat manipulation and finally just after the subject operated the Buss machine. In both experiments, after being exposed to differing levels of threat to their self-esteem in the form of a confederate’s supposed negative or positive (control) evaluation of them, subjects were given an opportunity to judge their evaluator, first for his/her performance on an extrasensory perception (ESP) task, and then as to his/her suitability for a permanent position on the experimental staff. While the self-esteem threat manipulation and the request for a hiring recommendation were the same in the two experiments, two different ways of operationalizing aggression were examined in the intermediate phase of the session. In the first experiment, subjects were given an opportunity to deliver shocks to their evaluator for mistakes on the ESP task. In the second experiment, by contrast, subjects were allowed to provide rewards to their evaluator for correct responses to this task. In the first experiment, the magnitude of aggression was operationalized as the level of shock delivered. However, in the second experiment, aggression was operationalized as the difference between the maximum possible reward and the amount of reward actually given. In this study, as in the previous experiments described above, it was deemed of interest to examine any variability ascribable to sex differences because of the role sex seems to play with respect to aggressive behavior (Frodi, McCauley and Thome, 1977; Weygandt-White, 1983). There were three aims for the experiments: (1) A major purpose was to explore whether or not the shock administration, reward deprivation and confederate evaluation procedures would show similar effects in response to the self-esteem provocation. In addition to the comparison of the three dependent measures, another purpose of the current study was the examination of individual differences in influencing the various measures of aggression. (2) Following previous research (Caprara et al., 1985a-d) it was expected that dissipationrumination would be predictive of subsequent aggression, regardless of mode of aggression. No predictions were made concerning the other scales, which were included for exploratory purposes. (3) It was expected that the self-esteem manipulation would produce significant differences in the various physiological measures taken immediately after the provocation. Second, in an exploratory vein, the question was examined as to whether physiological measures taken at different time points could serve as predictors of aggression following the presence or absence of provocation.
EXPERIMENT
1
Method Subjects. Subjects were undergraduate students at the University of Rome, between 20 and 30 yr of age, who volunteered to participate in experiments on learning and communication processes. Fifty males and 50 females were randomly assigned in equal number to the self-esteem threatening and to the self-esteem non-threatening condition (experimental/control) according to a 2 x 2 design with 25 subjects per cell. Before being introduced to the experimental setting, all subjects were asked to complete in a randomized order questionnaires measuring irritability, emotional instability, emotional vulnerability and dissipation-rumination. Experiment and procedure. Upon entering the laboratory subjects were met by the experimenter and interviewed for approx. 5 min. Immediately following, their ‘time one’ (tl) blood pressure and heart rate measurements were taken. The subjects were then asked to take a seat at a desk and, shortly after, a confederate (accomplice of the experimenter) was introduced. Both ‘subjects’ were asked not to talk or communicate with each other directly but to follow the experimenter’s instructions carefully. Then, to allow them an opportunity to observe each other, they were instructed to read carefully a long passage containing many names and places and to write the
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answers to five questions regarding the passage on a sheet of paper. As previously instructed, the confederate handed in his written answers immediately after the experimental subject. When receiving the subjects’ answers, regardless of their actual performance, the comments of the experimenter were fairly positive (“your performance is really an average good performance”) for subjects in both self-esteem threat manipulation groups. Self-esteem threat manipulation. Before being introduced to the next task, subjects were told that it explored the influence of interpersonal impressions on extrasensory perception and communication. For this purpose, they were first invited to report their first impressions of each other using a list of 9 bipolar adjectives presented in the form of a semantic differential inventory, and shortly after to exchange and examine adjective lists of each other. The experimental and control profiles were developed in preliminary studies in which other and more extreme profiles were eliminated because they did not seem credible. The ‘time two’ (t2) blood pressure and heart rate measurement were taken immediately after this manipulation. Thefirst aggression measurement (shock administration). After completing the above procedures, experimental subjects were seated at the ‘aggression machine’ console and given an ‘extrasensory perception task’ with the confederate sitting in an adjoining room. In this task the experimental subject was first asked to concentrate on the color of a card, then by sounding a buzzer to solicit a guess as to the color from the confederate and, finally, to indicate to the latter whether the response was correct. Subjects were informed that a correct response would be indicated by a luminous signal, and an incorrect response by an electric shock. There were 30 identical trials in a standard sequence including 21 incorrect responses (i) and 9 correct responses (c) in this order: (i, i, c, i, i, i, i, c, i, c, i, i, c, i, i, i, i, c, i, c, i, i, c, i, i, i, i, c, i, c). In the case of incorrect responses, the subject could choose from among 24 levels of shock. During pre-experimental instructions the subjects were exposed to a mild shock in order to convince them that actual shocks would be delivered. They were informed that the shocks could vary between very mild (1) and rather strong (24). Subjects were told that their assignment to the transmitter position and of the other subject (confederate) to the receiver position to have no particular importance and was motivated by a practical decision to place in the role of the transmitter that subject who first handed in the learning task. The confederate did not actually receive any shock, but simply recorded the shock level selected by the experimental subject. The experimenter was unaware of the group (experimental or control) to which the subject belonged. As noted above, in this experiment the intensity of selected shock was used as the first measure of aggression. The ‘time three’ (t3) blood pressure and heart rate measurement were then taken at the conclusion of the final ‘communication’ trial. The second aggression measurement (confederate rating). After completing the extrasensory perception task, the experimental subject was invited to evaluate the confederate’s suitability for a permanent position on the laboratory staff. Using a series of 10 step Likert scales, the experimental subject evaluated, respectively, the confederate’s interpersonal abilities (i.e. cooperation, tolerance), his reliability in following instructions (accuracy, attention), and then his suitability for regular employment in conducting psychological experiments. The cumulative evaluations of the confederate’s fitness for the position on the experimental staff served as a second aggression measure in addition to the levels of delivered shocks. At the completion of the experiment subjects were invited to fill in a checklist as to their feelings about the experiment and were then thoroughly acquainted with the real goal of the experiment and of the fact that they had not actually delivered any shock. Each session lasted approximately 40 min. Statistical analysis. Stepwise multiple regression analysis was selected as the main statistical method to analyze the various results (SPSSx; AA.VV.; 1983). First, stepwise multiple regression analyses were performed respectively on the levels of delivered shock and on the confederate evaluations having as predictors, sex, self-esteem threat and the individual differences measures of, respectively, irritability, emotional instability, emotional vulnerability and dissipation-rumination, and (t2-tl) and (t3-t2) differences in both blood pressure and heart rate measurements. Second, stepwise multiple regression analyses were performed with (t2-t 1) and (t3-t2) differences in systolic blood pressure, diastolic blood pressure and heart rate as criteria and using as predictors,
G. V. CAPRARAet al.
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Table
I.
Criterion
Stepwise multiple
variables
Shock levels
regression of selected variables on levels of shocks and on confederate’s evaluations as criterion variables Beta coefficient
Alpha level
Dissipation-rumination Emotional vulnerability
0.081 -0.081
0.000 0.034
Treatment
- 2.413
0.000
Selected variables
% Variance 10.31 4.71 Total
Confederate
sex, self-esteem threat emotional vulnerability
evaluations
and individual differences and dissipation-rumination.
measures
of irritability,
14.38 34.00
emotional
instability,
Results and discussion As shown in Table 1 while dissipation-rumination and emotional vulnerability were significant predictors of the level of selected shocks, self-esteem threat was the only significant predictor of the confederate evaluation. In the first case, the level of selected shock increased with higher rumination tendencies (r = 0.32, P < O.OOl), while it decreased with higher emotional vulnerability (r = -0.18, P < 0.05). In the second case, self-esteem threatened subjects gave less positive evaluations to the confederate than did subjects who received no self-esteem threat. Systolic blood pressure (t2-tl) measurement was the only physiological index in which a significant amount of variance was accounted for by any of the variables under consideration. As shown in Table 2, sex and self-esteem threat played a significant role; in particular, males showed higher increases in systolic blood pressure after being provoked than females did. These findings confirmed our expectations based on previous findings (Caprara, Cinanni, Passerini, Renzi and Zelli, 1983; Caprara et al., 1986b) in the case of the confederate evaluations, as well as in the case of the systolic variations due to the self-esteem threat manipulation. On the other hand, a rather different picture, with respect to previous findings, was found in the case of the selected levels of shock where no significant effect due to self-esteem threat manipulation was found and where individual differences played a more prominent role. The two aggression measures were only slightly (non-significantly) related, as was noticed in previous works (Caprara et al., 1986b). They appear to measure different aspects of aggressive behavior in relation to personal and situational variables. In this regard, the results suggest that delivering shocks may be a rather anxiety-provoking situation which has a different impact on people who are more prone to experience anxiety as the emotionally vulnerable are, as well as in people who are more prone to resort to aggression as the ruminators are. Thus, while the role of the antecedent provoking condition is important when subjects are offered the opportunity to give more or less positive evaluations, individual differences are more important when subjects are offered the opportunity to deliver an explicit noxious stimulation. EXPERIMENT
2
Method The methods were the same as for Experiment 1 except that rewards were given for correct responses instead of delivering shocks for wrong responses. Sixty males and 60 females were randomly assigned in equal number according to the same design as in Experiment 1. The subject was introduced to the same extrasensory perception task and invited to indicate the incorrect responses by means of a luminous signal and to indicate the correct responses by a reward
Table 2. Stepwise multiple
regression of selected variables criterion variable (Experiment
Criterion
Selected variables
variables
Systolic pressure
(t2-tl)
Sex Treatment
on systolic pressure (t2-tl) I)
Beta coefficient
Alpha level
5.720 3.880
0.000 0.030
as
% Variance 9.29 4.27 Total
13.56
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Table 3. Stepwise multiple regression of selected variables on levels of rewards and on confederate’s evaluations as criterion variables Criterion
variables
Reward levels Confederate evaluation
Selected variables Treatment Treatment
Beta coefficient
Alpha level
% Variance
- 5.926 -2.750
0.000 0.000
27.80 44.20
that could vary between 1 and 24 points according to the 24 choices made available by the apparatus. Each point was equal to 100 lire (about 6 U.S. cents) that was to be given to the confederate by the experimenter at the end of the experiment. There were 30 identical trials in a standard sequence including 18 incorrect responses (i) and 12 correct responses (c) in the following order: (i, i, c, c, i, i, i, c, i, c, i, c, c, i, i, i, i, c, i, c, i, i, c, i, i, i, c, c, i, c). In the case of correct responses the subject could chose from among 12 levels of rewards. The confederate recorded the level of the rewards selected by the experimental subject on a sheet of paper. For participating in the experiment the experimental subject was promised a set fee, although the actual amount of money was not specified. As noted above, in this experiment the amount of withheld rewards was used as the first measure of aggression. Results and discussion
As shown in Table 3, self-esteem threat was the only significant predictor of both reward withdrawal and of confederate evaluation. As expected, provoked subjects were less generous in giving rewards and less positive in their evaluations. Also, as in Experiment 1, only systolic blood pressure was affected by the examined variables as shown in Table 4. While self-esteem threat and sex played a significant role with respect to systolic pressure (t2-tl) difference, self-esteem threat and emotional vulnerability were significant with respect to the (t3-t2) difference. As also expected, the increase of systolic blood pressure due to self-esteem threat tended to dissipate with the passing of time; however, the males’ increase was higher than the females’ increase and the more emotionally vulnerable subjects were slower in the dissipation of systolic affects than less emotionally vulnerable subjects were.
GENERAL
DISCUSSION
AND CONCLUSIONS
While substantially confirming the results of previous experiments where similar procedures to instigate and to measure aggression have been used, present findings provide further elements for new directions of research. Ruminationdissipation and emotional vulnerability were, more than any other variables, significant predictors of selected levels of shock. However, self-esteem threat accounted for a large part of the explained variance when rewards were withdrawn and confederate evaluation was considered. As far as physiological indices are concerned, their auxiliary role in reflecting the impact of self-esteem threat found confirmation in the case of systolic blood pressure only, while none of these variables accounted for any variability in measures of aggression. Sex does not seem to play any significant role on the examined forms of aggression, but is relevant where physiological variations result associated with self-esteem threat.
Table 4. Stepwise multiple
regression of selected variables on systolic pressure (t2-tl criterion variable (Experiment 2)
Criterion
Selected variables
variables
Systolic pressure
(t2-tl)
Beta coefficient
Alpha level
Treatment Sex
6.330 3.830
0.000 0.013
Treatment Emotional
-5.650 0.197
0.006 0.016
and t3-t2) as
% Variance II.00 4.15 Total
(t3-12)
vulnerability
IS.15 4.93 4.55
Total
9.48
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Dependent upon the particular way of operationalizing aggression, personal and situational variables seem to account for different portions of the explained variance in the two experiments. It would seem that individual differences play differing roles in mediating instigations to aggression dependent upon whether the opportunity to aggress involves withholding rewards or administering punishments. Our findings show that rumination-dissipation and emotional vulnerability account for effects due to self-esteem threat when the available aggression is the delivery of obvious noxious stimulation to the provoking agent. In contrast, the same individual characteristics do not play any significant role when the available vehicle to express hostility is the opportunity to be less appreciative or less rewarding. Apparently, rewards are not the opposite of punishments, just as it is likely that positive evaluations are not the opposite of negative evaluations. Withdrawing rewards does not seem to have the same meaning as giving punishments, just as it is likely that giving less positive evaluation does not have the same meaning that giving negative evaluation has. It is plausible that, in general, people show more restraint in being punitive or actively negative than they do in being less positive or less rewarding. It is also likely that hostility in daily life more frequently takes the form of ‘not doing for’ or ‘not giving to’ other than the form of explicit attack and injury. Hostility is more likely shown in acts of omission rather than commission. It is likely that the more a behavior is seen as explicitly noxious as in delivering a shock, the more relevant will be the role of individual differences which may incline the subject to perceive such a behavior as blamable, justifiable or anxiety producing. In contrast to earlier experiments in which subjects frustrated by the experimenter gave shocks to an innocent confederate, the present procedure allowed subjects to retaliate directly against their provoker. It seems likely that the nature of the instigation and the opportunity to retaliate against their provoker reduced significantly the role of impulsivity in the present results by eliciting from the beginning the subjects’ inhibitions against aggression. It is also likely that a greater awareness of the whole situation has engaged subjects in a variety of cognitive processes in perceiving, attributing, and evaluating the inequities of the self-esteem provocation and, by consequence, their decision on the appropriateness of the response which was available to them. In this regard our findings suggest that, whether or not in the presence of self-esteem provocation, the personal inclination of subjects to resort to aggression plays a prominent role when explicit noxious stimulation is the available response. In contrast, self-esteem provocation shows its ability to elicit aggression, since the subject does not need to experience any feeling of blame or guilt in expressing his/her hostility in withdrawing rewards or in giving less positive evaluations. Previous research has called for attention to the various antecedents of aggression and hostility stressing the importance of situational variables. On the other hand, the study of individual differences or stable personality characteristics has been shown to be crucial to the understanding of the processes and mechanisms underlying the various forms of aggressive behavior. The present results suggest that, in addition to situation and person variables, the meanings, feelings and expectations associated with the different forms of aggressive behaviors should deserve an increasing
amount
of our attention
in the future.
Acknowledgements-The present research was supported by Minister0 Pubblica Istruzione, Grant (40%~60%) 198441985. We acknowledge the valuable contribution of D. Fromme in the writing of the manuscript.
a.a.
REFERENCES AA.VV. (1983) SPSSx. User’s Guide. McGraw-Hill, New York. Averill J. R. (1982) Anger and Aggression: An Essay on Emotion. Springer, New York. Berkowitz L. (1974) External determinants of impulsive aggression. In Determinants and Origins of Aggressive Behauior (Edited by Wit J. and Hartup W.), pp. 147-165. Mouton, Paris. Berkowitz L. (1974) Some determinants of impulsive aggression: Role of mediated associations with reinforcement for aggression. Psychol. Rm. 81, 1655176.
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Berkowitz L. (1983) The experience of anger as a parallel process in the display of impulsive, “angry” aggression. In Aggression: Theoretical and Empirical Review (Edited by Geen R. G. and Donnerstein E.), Vol. 1, pp. 103-134. Academic Press, New York. Berkowitz L. and Donnerstein E. (1983) External validity is more than skin deep: some answers to criticism of laboratory experiments (with special reference to research on aggression). Am. Psychol. 37, 245-257. Buss A. (1961) The Psychology of Aggression. Wiley, New York. Caprara G. V. (1986) Indicators of aggression: The Dissipation-Rumination Scale. Person. individ. Diff: 7, 763-769. Caprara G. V., Cinanni V., Passerini S, Renzi P. and Zelli A. (1983a) Caratteristiche e sviluppi di due scale per la misura dell’irritabilita e della suscettibilita emotiva: indicazioni di ricerca in ambito clinico. Psicol. clin. 3, 3233334. Caprara G. V., Conte M., Gennaro A. and Renzi P. (1983b) Attivazione psicodinamica subliminale e Irritabilita: contribute sperimentale. Comun. sci. Psicol. gen. 11, 147-158. Caprara G. V., Renzi P., Alcini P., D’Imperio G. and Travaglia G. (1983~) The instigation and the escalation of aggression reconsidered in a personological perspective: The role of irritability and of emotional susceptibility. Aggress. Behau. 9, 345-351. Caprara G. V., Renzi P., Alcini P., D’Imperio G. and Travaglia G. (1984a) Istigatori e mediatori della condotta aggressiva. G. ital. Psicol. 10, 113-128. Caprara G. V., Renzi P., Amolini P., D’Imperio G. and Travaglia G. (1984b) The eliciting cue value of aggressive slides, reconsidered in a personological perspective: The weapon effect and irritability. Eur. J. sot. Psychol. 14, 313-322. Caprara G. V., Coluzzi M., Mazzotti E., Renzi P. and Zelli A. (1985a) Effect of insult and dissipation-rumination on delayed aggression and hostility. Arch. Psicol. Neurol. Psichiat. 130-139. Caprara G. V., Renzi P., Mazzotti E., Pastorelli C. and Zelli A. (1985b) Temperamental and personality variables related to delayed aggression and hostility. In Multidisciplinary Approaches IO Conflict and Appeasement in Animals and Men: Proceedings of the 3rd ISRA European Conference (Edited by Le Moli F.). Instituto di Zoologia, Universita di Parma. Caprara G. V., Cinanni V., D’Imperio G., Passerini S., Renzi P. and Travaglia G. (1985~) Indicators of impulsive aggression: Present status of research on irritability and emotional susceptibility scales. Person. indiuid. 01% 6, 665674. Caprara G. V., Borgogni L., Cinanni V., Di Giandomenico F. and Passerini S. (1985d) Indicatori della condotta aggressiva. G. ital. Psicol. 12, 515-539. Caprara G. V., Renzi P., D’Augello D., D’Imperio G., Rielli I. and Travaglia G. (1986a) Interpolating physical exercise between provocation and aggression: the role of irritability and emotional susceptibility. Aggress. Behav. 12, 83-91. Caprara G. V., Passerini S., Pastorelli C., Renzi P. and Zelli A. (1986b) Instigating and measuring interpersonal aggression and hostility. Aggress. Behao. In press. Dollard J., Doob L., Miller N., Mower 0. and Sears R. (1939) Frustration and Aggression. Yale University Press, New Haven. Frodi A., Macauley J. and Thome P. (1977) Are women always less aggressive than men? A review of experimental literature. Psychol. Bull. 84, 634660. Konecni V. (1975) Annoyance type and duration of postannoyance activity and aggression: The cathartic effect. J. exp. Psychol. 104, 76102. Konecni V. (1984) Methodological issues in human aggression research. In Aggression in Children and Youth (Edited by Kaplan K., Konecni V. and Novaco K.), Vol. 11, pp. 143. Nijhoff, The Hague. Renzi P., Caprara G. V., Crudele C., Galante A. and Giannone R. (1984) The role of acoustic stimulation on aggression. Rass. Psicol. 3, 27737. Zillmann D. (1979) Hostility and Aggression. Earlbaum, Hillsdale, N.J. Zillmann D. (1983) Arousal and aggression. In Aggression: Theoretical and Empirical Review (Edited by Geen R. G. and Donnerstein E.), Vol. 1, pp. 755134. Academic Press, New York. Weygandt-White J. (1983) Sex and gender issues in aggression research. In Aggression: Theoretical and Empirical Review (Edited by Geen R. G. and Donnerstein E.), Vol. 2, pp. l-26. Academic Press, New York.
1987 Copyright
0
0191s8869/87 1987 Pergamon
INDIVIDUAL DIFFERENCES AND MEASURES AGGRESSION IN LABORATORY STUDIES G.
$3.00 + 0.00
JournalsLtd
OF
V. CAPRARA, T. GARGARO, C. PASTORELLI, M. PREZZA, P. RENZI and A. ZELLI
Dipartimento di Psicologia, Universith degh Studi di Roma “La Sapienza”, 00185 Italy (Received
19 December
Via degli Apuli S-Rome,
1986)
Summary-After inducing hostility toward a confederate by threatening subjects’ self-esteem, subjects were then given the opportunity either to deliver shocks (Experiment I) or to withhold rewards (Experiment 2) from their confederate. Physiological measures were taken prior to the hostility induction, shortly after the induction and, finally, after the opportunity to aggress. Measures of individual differences relating to aggressive behavior were also considered. While the experimental manipulation was the best predictor in the ‘withholding rewards’ condition, measures of dissipation-rumination tendencies and emotional vulnerability were the best predictors in the ‘shock administration’ condition. In both conditions, systolic blood pressure seemed to reflect differences in arousal as a function of the hostility induction procedures, while subjects in the withhold rewards procedure also showed a decrease in systolic pressure after having an opportunity to aggress toward the confederate. It was concluded that not only is the withholding of rewards a more ethically acceptable procedure than shock administration, but it is also more likely to reflect experimental rather than individual difference affects.
INTRODUCTION
The present study addressed three main issues of experimental research on human aggression related, respectively, to the role of individual differences in personality characteristics, to the use of physiological indices and to the methods used to instigate and to measure aggression in laboratory studies. The influence of personality on aggression: Irritability, emotional susceptibility and dissipationrumination
As noted elsewhere (Caprara, Renzi, D’Augello, D’Imperio, Rielli and Travaglia, 1985a), there has been increased attention in recent years to the role of stable personality characteristics in mediating cognitive and emotional aspects of aggressive behavior. In particular, where temperament or personality constructs and observable behaviors can be related in a meaningful theoretical network, the use of both individual differences and experimental approaches may provide the means to develop a more comprehensive theory, encompassing both person and situation variables. Accordingly, a program of research has been initiated which has identified irritability and emotional susceptibility as personality constructs particularly suited to the study of reactive or impulsive aggression (Berkowitz, 1974; Caprara, Cinanni, D’Imperio, Passerini, Renzi and Travaglia, 198%). Irritability is defined as the tendency to react impulsively, controversially, or rudely to the slightest provocation or disagreement. Emotional susceptibility is defined as the tendency to experience feelings of discomfort, helplessness, inadequacy and vulnerability. While irritability manifests itself as the tendency to behave offensively, emotional susceptibility is reflected in the tendency to be defensive. Both constructs are related to one’s capacity or incapacity to dominate and maintain full emotional control when frustrated, to dominate one’s own reactions when exposed to various sources of stress, failure and provocation, and to overcome excitement and react adequately in imagined or real situations of danger, threat or attack. Both constructs are assumed to reflect a tendency to overreact emotionally to events that are perceived as frustrating, as well as to perceive events as frustrating. PA.10
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These constructs derive from the literature on the links between frustration, emotion, and aggression (Zillmann, 1979; Averill, 1982) and were developed by an empirical analysis which has led to the construction of two scales showing common latent structure, despite efforts in creating unifactorial solutions and despite obvious differences in the items and related behaviors. For example, the 30-item Irritability scale contains items such as: “I think I am rather touchy”; “Sometimes I shout, hit, kick and let off steam”; while the 40-item Emotional Susceptibility scale has items such as: “Fear of failure worries me more than necessary”; “Sometimes I feel on edge”. As indicators of tolerance to frustration, both constructs appear particularly suited to explore the frustration-aggression hypothesis (Dollard, Doob, Miller, Mowrer and Sears, 1939) and its derived hypotheses concerning forms of aggression in which excitatory and involuntary components are likely to play a major role (Berkowitz, 1983; Zillmann, 1979, 1983). In a number of studies using a slightly modified version of the tradition Buss (1961) aggression machine paradigm, highly irritable subjects and highly emotionally susceptible subjects selected, as was expected, higher levels of shock respectively than low irritable subjects and low emotionally susceptible subjects, particularly when previously provoked (Caprara, Renzi, Alcini, D’Imperio and Travaglia, 1983~). Similar findings have been replicated in studies aimed at exploring effects on subsequent aggression of interpolating between a self-esteem provocation and the opportunity to aggress either exposure to aggression eliciting cues such as slides portraying weapons (Caprara, Renzi, Alcini, D’Imperio and Travaglia, 1984a; Caprara, Renzi, Amolini, D’Imperio and Travaglia, 1984b) or physical exercise which increases sympathetic arousal (Caprara et al., 1986a). In all these experiments either irritability or emotional susceptibility, as well as their interaction with self-esteem provocation, were found to account for a substantial portion of the non-random variance with respect to the intensity of subsequent aggression. In contrast, a rather different picture resulted in experiments where the opportunity to aggress did not immediately follow the self-esteem provocation or where other activities able to elicit, maintain, or increase subsequent aggression were not interpolated between the self-esteem provocation and the opportunity to aggress. The passing of time by itself practically eliminated the effect elicited in prior experiments due to the self-esteem provocation and considerably decreased the role of individual differences (Caprara, Conte, Gennaro and Renzi, 1983b; Renzi, Caprara, Crudele, Galante and Giannone, 1984). Consequently, the importance of processes occurring during the time between instigation and expression, such as the cognitive processes which store the experience of provocation and the desire for retaliation, become questions for more serious investigation. In this regard Konecni (1975) has reported on the effects of dissipation and rumination in altering aggressive conduct as a function of the lapse of time separating the instigation to aggress and the moment in which aggression occurs. Since dissipation and rumination might be considered as opposite ends of a single dimension of behavior, they might be also considered as opposite manifestations along a similar continuum of a personality construct characterized, at one end, by an inclination toward rapid dissipation and minimal rumination and, at the other end, by an inclination toward slow dissipation and prolonged rumination. Thus, with the passage of time, ‘dissipators’ would be expected to get over quickly any ill feelings or desire to retaliate, while ‘ruminators’ would be expected to maintain or even increase their desire for vengeance. Accordingly, a new scale has been generated whose psychometric characteristics appear very satisfactory for both the Italian and English version. Sample items of the 20-item dissipationrumination scale are: “It takes many years for me to get rid of a grudge”; “I do not forgive easily once I am offended” (Caprara, 1986). This new scale has proved to be a valid indicator of hostility in experiments in which subjects, after having been threatened in their self-esteem by a confederate, had the opportunity to retaliate against their provoker immediately, 24 hours after provocation, and a week after provocation (Caprara, Coluzzi, Mazzotti, Renzi and Zelli, 1985a; Caprara, Renzi, Mazzotti, Pastorelli and Zelli, 1985b). In these experiments the various personality measures accounted for a substantial part of the non-random variance in levels of administered shocks and contributed to the elaboration of better articulated hypotheses.
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Physiological measures in aggression research
Physiological indices such as systolic and diastolic blood pressure, heart rate, skin conductance and finger temperature have been commonly used-as dependent measures in aggression research. As recently reviewed by Konecni (1984), the main tendency “has been to use them as auxiliary measures, in conjunction with the behavioral ones or, more importantly, as a means of scaling the impact and/or the time course of certain (especially arousal related) experimental variables” (p. 20). Findings are often contradictory and difficult to interpret due to a number of methodological problems related to physiological measures and their statistical analysis, as well as because of a number of theoretical problems related to the meaning and value of physiologial measures in research on aggression. While blood pressure and heart rate changes have frequently been associated with various aggression eliciting cues and aggressive reactions, there is no common pattern or trend among the different indices and a great intraindividual variability is noticed. We are not aware of any study in which physiological indices used as moderator variables or predictors have resulted in a significant role with respect to aggressive behavior. It is likely that most of the methodological problems indicated above would occur also in any case where individual differences in physiological reactions to various aggression eliciting cues or various forms of expression of aggression were examined as antecedent processes rather than as mere correlates of aggressive behavior. Yet, we believe that this direction of research should deserve more attention than it has received so far. Methods used to instigate and measure aggression
As noted elsewhere (Caprara, Passerini, Pastorelli, Renzi and Zelli, 1986b) laboratory studies of aggression are faced with a number of serious methodological problems. Besides the obvious question of the degree to which the measures employed are subject to such experimental artifacts as demand cues and evaluation apprehension, there is uncertainty regarding the external validity of the aggression measures and the unstandardized nature of many of the experimental manipulations. In particular, most of the criticism regarding the Buss aggression machine paradigm has consisted of two types: first, real life aggressors rarely, if ever, attack by giving electric shocks or blasts of unpleasant noise; second, it is an ethically suspect procedure which encourages experimental subjects to inflict physical harm and/or to believe they are to inflict physical harm on another person. While Berkowitz and Donnerstein (1983) have answered the first objection by pointing out that it is the meaning the subjects give their actions that determines whether this behavior is aggressive or not, their answer paradoxically reinforces the validity of the concern expressed through the second objection. In particular, the concern over long-lasting and negative effects of inducing someone to hurt another person is reinforced by the occurrence of guilt and/or aggressive anxiety which is often found in association with the delivery of noxious stimulation. To answer both objections, a new laboratory procedure was developed to operationalize aggression in a different manner than in the original Buss procedure. In Buss’s original procedure, subjects selected levels of noxious stimulation to deliver to a confederate in order to communicate mistakes in a learning or extrasensory perception task. Responses greater than the lowest level noxious stimulation were regarded as aggressive. In the current revised procedure, using the same response machine, subjects select rewards to communicate the correct responses to a confederate and selections other than the maximum possible reward are regarded as aggressive. The injury in the revised method is relatively subtle and consists of depriving the other individual of the maximum amount of rewards, with no personal advantage, rather than apparently harming the subjects physically, as in Buss’s procedure. The first study in which the two procedures have been compared confirms the validity of the new procedure and recommends it as a more convenient procedure to minimize subjects’ distorting reactions due to aggression anxiety or evaluation apprehension and to minimize ethical concerns (Caprara et al., 1986b). AIM
OF THE
CONTRIBUTION
Two experiments were conceived in which the self-esteem threat manipulation used in previous experiments (Caprara et al., 1985a, 1986b) was used to instigate aggression. Measures of irritability,
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emotional instability, emotional vulnerability and dissipation-rumination were obtained for all subjects prior to the experiment. Emotional instability and emotional vulnerability scales resulted from a revision of the original emotional susceptibility scale (Caprara, Borgogni, Cinanni, Di Giandomenico and Passerini, 1985d). Systolic and diastolic blood pressure and heart rate were also taken, the first prior to the experiment, next after the self-esteem threat manipulation and finally just after the subject operated the Buss machine. In both experiments, after being exposed to differing levels of threat to their self-esteem in the form of a confederate’s supposed negative or positive (control) evaluation of them, subjects were given an opportunity to judge their evaluator, first for his/her performance on an extrasensory perception (ESP) task, and then as to his/her suitability for a permanent position on the experimental staff. While the self-esteem threat manipulation and the request for a hiring recommendation were the same in the two experiments, two different ways of operationalizing aggression were examined in the intermediate phase of the session. In the first experiment, subjects were given an opportunity to deliver shocks to their evaluator for mistakes on the ESP task. In the second experiment, by contrast, subjects were allowed to provide rewards to their evaluator for correct responses to this task. In the first experiment, the magnitude of aggression was operationalized as the level of shock delivered. However, in the second experiment, aggression was operationalized as the difference between the maximum possible reward and the amount of reward actually given. In this study, as in the previous experiments described above, it was deemed of interest to examine any variability ascribable to sex differences because of the role sex seems to play with respect to aggressive behavior (Frodi, McCauley and Thome, 1977; Weygandt-White, 1983). There were three aims for the experiments: (1) A major purpose was to explore whether or not the shock administration, reward deprivation and confederate evaluation procedures would show similar effects in response to the self-esteem provocation. In addition to the comparison of the three dependent measures, another purpose of the current study was the examination of individual differences in influencing the various measures of aggression. (2) Following previous research (Caprara et al., 1985a-d) it was expected that dissipationrumination would be predictive of subsequent aggression, regardless of mode of aggression. No predictions were made concerning the other scales, which were included for exploratory purposes. (3) It was expected that the self-esteem manipulation would produce significant differences in the various physiological measures taken immediately after the provocation. Second, in an exploratory vein, the question was examined as to whether physiological measures taken at different time points could serve as predictors of aggression following the presence or absence of provocation.
EXPERIMENT
1
Method Subjects. Subjects were undergraduate students at the University of Rome, between 20 and 30 yr of age, who volunteered to participate in experiments on learning and communication processes. Fifty males and 50 females were randomly assigned in equal number to the self-esteem threatening and to the self-esteem non-threatening condition (experimental/control) according to a 2 x 2 design with 25 subjects per cell. Before being introduced to the experimental setting, all subjects were asked to complete in a randomized order questionnaires measuring irritability, emotional instability, emotional vulnerability and dissipation-rumination. Experiment and procedure. Upon entering the laboratory subjects were met by the experimenter and interviewed for approx. 5 min. Immediately following, their ‘time one’ (tl) blood pressure and heart rate measurements were taken. The subjects were then asked to take a seat at a desk and, shortly after, a confederate (accomplice of the experimenter) was introduced. Both ‘subjects’ were asked not to talk or communicate with each other directly but to follow the experimenter’s instructions carefully. Then, to allow them an opportunity to observe each other, they were instructed to read carefully a long passage containing many names and places and to write the
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889
answers to five questions regarding the passage on a sheet of paper. As previously instructed, the confederate handed in his written answers immediately after the experimental subject. When receiving the subjects’ answers, regardless of their actual performance, the comments of the experimenter were fairly positive (“your performance is really an average good performance”) for subjects in both self-esteem threat manipulation groups. Self-esteem threat manipulation. Before being introduced to the next task, subjects were told that it explored the influence of interpersonal impressions on extrasensory perception and communication. For this purpose, they were first invited to report their first impressions of each other using a list of 9 bipolar adjectives presented in the form of a semantic differential inventory, and shortly after to exchange and examine adjective lists of each other. The experimental and control profiles were developed in preliminary studies in which other and more extreme profiles were eliminated because they did not seem credible. The ‘time two’ (t2) blood pressure and heart rate measurement were taken immediately after this manipulation. Thefirst aggression measurement (shock administration). After completing the above procedures, experimental subjects were seated at the ‘aggression machine’ console and given an ‘extrasensory perception task’ with the confederate sitting in an adjoining room. In this task the experimental subject was first asked to concentrate on the color of a card, then by sounding a buzzer to solicit a guess as to the color from the confederate and, finally, to indicate to the latter whether the response was correct. Subjects were informed that a correct response would be indicated by a luminous signal, and an incorrect response by an electric shock. There were 30 identical trials in a standard sequence including 21 incorrect responses (i) and 9 correct responses (c) in this order: (i, i, c, i, i, i, i, c, i, c, i, i, c, i, i, i, i, c, i, c, i, i, c, i, i, i, i, c, i, c). In the case of incorrect responses, the subject could choose from among 24 levels of shock. During pre-experimental instructions the subjects were exposed to a mild shock in order to convince them that actual shocks would be delivered. They were informed that the shocks could vary between very mild (1) and rather strong (24). Subjects were told that their assignment to the transmitter position and of the other subject (confederate) to the receiver position to have no particular importance and was motivated by a practical decision to place in the role of the transmitter that subject who first handed in the learning task. The confederate did not actually receive any shock, but simply recorded the shock level selected by the experimental subject. The experimenter was unaware of the group (experimental or control) to which the subject belonged. As noted above, in this experiment the intensity of selected shock was used as the first measure of aggression. The ‘time three’ (t3) blood pressure and heart rate measurement were then taken at the conclusion of the final ‘communication’ trial. The second aggression measurement (confederate rating). After completing the extrasensory perception task, the experimental subject was invited to evaluate the confederate’s suitability for a permanent position on the laboratory staff. Using a series of 10 step Likert scales, the experimental subject evaluated, respectively, the confederate’s interpersonal abilities (i.e. cooperation, tolerance), his reliability in following instructions (accuracy, attention), and then his suitability for regular employment in conducting psychological experiments. The cumulative evaluations of the confederate’s fitness for the position on the experimental staff served as a second aggression measure in addition to the levels of delivered shocks. At the completion of the experiment subjects were invited to fill in a checklist as to their feelings about the experiment and were then thoroughly acquainted with the real goal of the experiment and of the fact that they had not actually delivered any shock. Each session lasted approximately 40 min. Statistical analysis. Stepwise multiple regression analysis was selected as the main statistical method to analyze the various results (SPSSx; AA.VV.; 1983). First, stepwise multiple regression analyses were performed respectively on the levels of delivered shock and on the confederate evaluations having as predictors, sex, self-esteem threat and the individual differences measures of, respectively, irritability, emotional instability, emotional vulnerability and dissipation-rumination, and (t2-tl) and (t3-t2) differences in both blood pressure and heart rate measurements. Second, stepwise multiple regression analyses were performed with (t2-t 1) and (t3-t2) differences in systolic blood pressure, diastolic blood pressure and heart rate as criteria and using as predictors,
G. V. CAPRARAet al.
890
Table
I.
Criterion
Stepwise multiple
variables
Shock levels
regression of selected variables on levels of shocks and on confederate’s evaluations as criterion variables Beta coefficient
Alpha level
Dissipation-rumination Emotional vulnerability
0.081 -0.081
0.000 0.034
Treatment
- 2.413
0.000
Selected variables
% Variance 10.31 4.71 Total
Confederate
sex, self-esteem threat emotional vulnerability
evaluations
and individual differences and dissipation-rumination.
measures
of irritability,
14.38 34.00
emotional
instability,
Results and discussion As shown in Table 1 while dissipation-rumination and emotional vulnerability were significant predictors of the level of selected shocks, self-esteem threat was the only significant predictor of the confederate evaluation. In the first case, the level of selected shock increased with higher rumination tendencies (r = 0.32, P < O.OOl), while it decreased with higher emotional vulnerability (r = -0.18, P < 0.05). In the second case, self-esteem threatened subjects gave less positive evaluations to the confederate than did subjects who received no self-esteem threat. Systolic blood pressure (t2-tl) measurement was the only physiological index in which a significant amount of variance was accounted for by any of the variables under consideration. As shown in Table 2, sex and self-esteem threat played a significant role; in particular, males showed higher increases in systolic blood pressure after being provoked than females did. These findings confirmed our expectations based on previous findings (Caprara, Cinanni, Passerini, Renzi and Zelli, 1983; Caprara et al., 1986b) in the case of the confederate evaluations, as well as in the case of the systolic variations due to the self-esteem threat manipulation. On the other hand, a rather different picture, with respect to previous findings, was found in the case of the selected levels of shock where no significant effect due to self-esteem threat manipulation was found and where individual differences played a more prominent role. The two aggression measures were only slightly (non-significantly) related, as was noticed in previous works (Caprara et al., 1986b). They appear to measure different aspects of aggressive behavior in relation to personal and situational variables. In this regard, the results suggest that delivering shocks may be a rather anxiety-provoking situation which has a different impact on people who are more prone to experience anxiety as the emotionally vulnerable are, as well as in people who are more prone to resort to aggression as the ruminators are. Thus, while the role of the antecedent provoking condition is important when subjects are offered the opportunity to give more or less positive evaluations, individual differences are more important when subjects are offered the opportunity to deliver an explicit noxious stimulation. EXPERIMENT
2
Method The methods were the same as for Experiment 1 except that rewards were given for correct responses instead of delivering shocks for wrong responses. Sixty males and 60 females were randomly assigned in equal number according to the same design as in Experiment 1. The subject was introduced to the same extrasensory perception task and invited to indicate the incorrect responses by means of a luminous signal and to indicate the correct responses by a reward
Table 2. Stepwise multiple
regression of selected variables criterion variable (Experiment
Criterion
Selected variables
variables
Systolic pressure
(t2-tl)
Sex Treatment
on systolic pressure (t2-tl) I)
Beta coefficient
Alpha level
5.720 3.880
0.000 0.030
as
% Variance 9.29 4.27 Total
13.56
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Table 3. Stepwise multiple regression of selected variables on levels of rewards and on confederate’s evaluations as criterion variables Criterion
variables
Reward levels Confederate evaluation
Selected variables Treatment Treatment
Beta coefficient
Alpha level
% Variance
- 5.926 -2.750
0.000 0.000
27.80 44.20
that could vary between 1 and 24 points according to the 24 choices made available by the apparatus. Each point was equal to 100 lire (about 6 U.S. cents) that was to be given to the confederate by the experimenter at the end of the experiment. There were 30 identical trials in a standard sequence including 18 incorrect responses (i) and 12 correct responses (c) in the following order: (i, i, c, c, i, i, i, c, i, c, i, c, c, i, i, i, i, c, i, c, i, i, c, i, i, i, c, c, i, c). In the case of correct responses the subject could chose from among 12 levels of rewards. The confederate recorded the level of the rewards selected by the experimental subject on a sheet of paper. For participating in the experiment the experimental subject was promised a set fee, although the actual amount of money was not specified. As noted above, in this experiment the amount of withheld rewards was used as the first measure of aggression. Results and discussion
As shown in Table 3, self-esteem threat was the only significant predictor of both reward withdrawal and of confederate evaluation. As expected, provoked subjects were less generous in giving rewards and less positive in their evaluations. Also, as in Experiment 1, only systolic blood pressure was affected by the examined variables as shown in Table 4. While self-esteem threat and sex played a significant role with respect to systolic pressure (t2-tl) difference, self-esteem threat and emotional vulnerability were significant with respect to the (t3-t2) difference. As also expected, the increase of systolic blood pressure due to self-esteem threat tended to dissipate with the passing of time; however, the males’ increase was higher than the females’ increase and the more emotionally vulnerable subjects were slower in the dissipation of systolic affects than less emotionally vulnerable subjects were.
GENERAL
DISCUSSION
AND CONCLUSIONS
While substantially confirming the results of previous experiments where similar procedures to instigate and to measure aggression have been used, present findings provide further elements for new directions of research. Ruminationdissipation and emotional vulnerability were, more than any other variables, significant predictors of selected levels of shock. However, self-esteem threat accounted for a large part of the explained variance when rewards were withdrawn and confederate evaluation was considered. As far as physiological indices are concerned, their auxiliary role in reflecting the impact of self-esteem threat found confirmation in the case of systolic blood pressure only, while none of these variables accounted for any variability in measures of aggression. Sex does not seem to play any significant role on the examined forms of aggression, but is relevant where physiological variations result associated with self-esteem threat.
Table 4. Stepwise multiple
regression of selected variables on systolic pressure (t2-tl criterion variable (Experiment 2)
Criterion
Selected variables
variables
Systolic pressure
(t2-tl)
Beta coefficient
Alpha level
Treatment Sex
6.330 3.830
0.000 0.013
Treatment Emotional
-5.650 0.197
0.006 0.016
and t3-t2) as
% Variance II.00 4.15 Total
(t3-12)
vulnerability
IS.15 4.93 4.55
Total
9.48
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Dependent upon the particular way of operationalizing aggression, personal and situational variables seem to account for different portions of the explained variance in the two experiments. It would seem that individual differences play differing roles in mediating instigations to aggression dependent upon whether the opportunity to aggress involves withholding rewards or administering punishments. Our findings show that rumination-dissipation and emotional vulnerability account for effects due to self-esteem threat when the available aggression is the delivery of obvious noxious stimulation to the provoking agent. In contrast, the same individual characteristics do not play any significant role when the available vehicle to express hostility is the opportunity to be less appreciative or less rewarding. Apparently, rewards are not the opposite of punishments, just as it is likely that positive evaluations are not the opposite of negative evaluations. Withdrawing rewards does not seem to have the same meaning as giving punishments, just as it is likely that giving less positive evaluation does not have the same meaning that giving negative evaluation has. It is plausible that, in general, people show more restraint in being punitive or actively negative than they do in being less positive or less rewarding. It is also likely that hostility in daily life more frequently takes the form of ‘not doing for’ or ‘not giving to’ other than the form of explicit attack and injury. Hostility is more likely shown in acts of omission rather than commission. It is likely that the more a behavior is seen as explicitly noxious as in delivering a shock, the more relevant will be the role of individual differences which may incline the subject to perceive such a behavior as blamable, justifiable or anxiety producing. In contrast to earlier experiments in which subjects frustrated by the experimenter gave shocks to an innocent confederate, the present procedure allowed subjects to retaliate directly against their provoker. It seems likely that the nature of the instigation and the opportunity to retaliate against their provoker reduced significantly the role of impulsivity in the present results by eliciting from the beginning the subjects’ inhibitions against aggression. It is also likely that a greater awareness of the whole situation has engaged subjects in a variety of cognitive processes in perceiving, attributing, and evaluating the inequities of the self-esteem provocation and, by consequence, their decision on the appropriateness of the response which was available to them. In this regard our findings suggest that, whether or not in the presence of self-esteem provocation, the personal inclination of subjects to resort to aggression plays a prominent role when explicit noxious stimulation is the available response. In contrast, self-esteem provocation shows its ability to elicit aggression, since the subject does not need to experience any feeling of blame or guilt in expressing his/her hostility in withdrawing rewards or in giving less positive evaluations. Previous research has called for attention to the various antecedents of aggression and hostility stressing the importance of situational variables. On the other hand, the study of individual differences or stable personality characteristics has been shown to be crucial to the understanding of the processes and mechanisms underlying the various forms of aggressive behavior. The present results suggest that, in addition to situation and person variables, the meanings, feelings and expectations associated with the different forms of aggressive behaviors should deserve an increasing
amount
of our attention
in the future.
Acknowledgements-The present research was supported by Minister0 Pubblica Istruzione, Grant (40%~60%) 198441985. We acknowledge the valuable contribution of D. Fromme in the writing of the manuscript.
a.a.
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