A comparison of human aggression committed by groups and individuals: An interindividual–intergroup discontinuity

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Abstract

Experimental research comparing aggressive behavior committed by groups and individuals is important but sparse. This experiment compared aggressive behavior (i.e., amount of hot sauce allocated for others to consume) in four types of interactions: intergroup, interindividual, group-to-individual, and individual-to-group. The results revealed that intergroup interactions were significantly more aggressive than interindividual interactions. In addition, groups allocated and received significantly more hot sauce than individuals. These effects were not explained by diffusion of responsibility or trait aggressiveness. The experiment reveals two noteworthy conclusions: (1) the interindividual–intergroup discontinuity effect extends to aggressive behavior and (2) interactions in which a group is either the source or target of aggression are situational influences that can increase it.

Introduction

In the Robber’s Cave study (Sherif, Harvey, White, Hood, & Sherif, 1961), researchers posed as counselors to investigate interactions among 11- and 12-year-old boys who believed they were attending an ordinary camp. The boys were divided into two groups and arrived at the camp separately from each other so members of each group could form ties. This separation continued for 8 days at which point researchers allowed the groups to discover each other. At the boys’ request, researchers allowed the groups to compete in a number of games (e.g., baseball or football). As the competition grew, the favorable attitude for one’s group and dislike for the opposing group increased. Individuals called members of the opposing group “sneaks” and “cheaters.” The interactions between the groups eventually became aggressive (e.g., stealing, throwing food, or fist-fights).

Although the Robber’s Cave study provided a basis for the investigation of aggression by groups, laboratory research in this area is almost nonexistent. However, the nature of aggression committed by groups makes it important. One does not have to ponder long to recall extreme acts of aggression committed by a group. Recent examples include the sexual assaults of several women during the 2000 Puerto Rican day parade in New York City (Claffey, 2000) and the fatal beating of a 36-year old Wisconsin male by 20 children (Thorsen, 2002). In the context of this paper, we rely upon Baron and Richardson’s (1994) definition of aggression, which states that aggression is a behavior meant to harm another living being that intends to avoid such harm.

In contrast to our lack of knowledge related to the factors that predict group aggression, we know much about the factors that predict individual aggression (e.g., trait aggressiveness, affect, or aggressive thoughts; Anderson & Bushman, 2002). Because of the potentially extreme nature of aggression by groups (e.g., gangs or soccer hooligans), it is important to uncover variables that relate to it. Such an analysis will extend and provide a more complete picture of aggression in general, not just as it relates to the individual.

Although experimental research on aggression committed by groups is scarce, at least two studies compared aggression committed by groups and individuals (Jaffe & Yinon, 1979; Jaffe, Shapir, & Yinon, 1981). Both studies used the teacher and learner paradigm based on Milgram’s (1965) obedience research. The independent variable in these studies was the teacher (individual or group), and the dependent variable was the level of electrical shock participants purportedly gave to others. Jaffe and colleagues found that, when a confederate failed a task, groups acting as teachers delivered significantly more severe shocks as compared to individuals acting as teachers.

Jaffe et al. (1981) also had participants rate how personally responsible they felt for the shock administration. Individuals in the groups rated themselves as significantly less responsible than individuals acting alone. Because of this result, Jaffe et al. suggested that diffused responsibility was associated with increased aggression by groups. However, they did not offer statistical support (i.e., correlational or mediational) for the relationship between aggression and perceived responsibility. It is possible that the group or individual manipulation increased aggressive behavior and decreased personal responsibility independently of one another.

Although the research by Jaffe and colleagues provides formative steps toward understanding aggression by groups and individuals, important questions remain. The teachers were instructed to teach the learner using the shock machine. This measure of aggression (i.e., shock level) may not be a true indication of aggressive action because participants may have wanted to teach the learner (per experimenter instructions) rather than be aggressive. Would this same difference between groups and individuals be found in research that does not use the teacher and learner paradigm? In addition, does diffusion of responsibility explain why groups aggress more than individuals, or does it simply co-occur as a result of a grouping manipulation?

Another basis for considering aggression by groups is to consider the evidence regarding competition and cooperation. Research concerning competition and cooperation may provide some hints to the importance not only of the group or individual source of aggression (cf., Jaffe and colleagues), but also the victim (i.e., target of aggression). Relevant research on competition and cooperation among groups uses the prisoner’s dilemma. In the prisoner’s dilemma, one party interacts with another party in which each party can make one of two choices (cooperation or competition). The outcome of these choices usually involves a monetary reward. If both choose the cooperative alternative, both receive a moderate reward. If both choose the competitive alternative, both receive a nominal reward. However, if one party chooses to cooperate and the other party chooses to compete, the competitive party receives a high reward, and the cooperative party receives a small reward. This situation involves a conflict for the parties because the option with the greatest reward also has the greatest risk.

Research examining the prisoner’s dilemma when both parties are groups (intergroup) found that groups are consistently and substantially more competitive and less cooperative than when both parties are individuals (interindividual). This difference is known as the interindividual–intergroup discontinuity effect (e.g., Insko et al., 1987, Insko et al., 1988, Insko et al., 1992, Insko et al., 1993, Insko et al., 1994, Insko et al., 1998, Insko et al., 2001; McCallum et al., 1985; Schopler et al., 1993, Schopler et al., 1994, Schopler et al., 2001; Schopler, Insko, Drigotas, Pemberton, & Cox, 1995). It is interesting to note that Insko et al. (2001) suggest that this greater intergroup competition may also be reflected in conflict and aggression (e.g., ethnic conflicts).

One explanation that Insko et al. (2001) use to explain the interindividual–intergroup discontinuity effect relates to identifiability. This explanation is based on the belief that non-normative behavior (i.e., competition) is more identifiable by opponents in interindividual interactions (versus intergroup interactions). This explanation is similar to the concept of diffusion of responsibility. A diffusion of responsibility explanation suggests that, because individuals are part of a group and less identifiable, perceived responsibility for acting counter to a social norm (competing) is diffused among the group members. This explanation would suggest that identifiability relates to increased competition when a group versus an individual is the source of competition. Another explanation for the interindividual–intergroup discontinuity effect is based on distrust. Insko and colleagues’ research finds that participants believe groups are less trustworthy than individuals, which results in increased competition. This explanation would suggest that distrust relates to increased competition when a group versus an individual is the target of competition.

The interindividual–intergroup discontinuity research (Insko & colleagues) and the group aggression studies (Jaffe & colleagues) provide a basis for speculating what might occur when investigating group and individual aggression. Because interindividual–intergroup discontinuity research finds that intergroup interactions are more competitive and less cooperative than interindividual interactions, it seems likely that both the source and target of aggressive behavior would be important. If groups are viewed as less trustworthy than individuals, it is likely that groups would receive more aggression than lone individuals (i.e., target of the aggression). In addition, if groups are more likely to compete than individuals because members are less identifiable, it is likely that groups would commit more aggression than lone individuals (i.e., source of aggression). Therefore, to understand the effect the source (i.e., groups or individuals) and target (i.e., groups or individuals) have on aggression, an experimental manipulation of both is desirable. This type of design would answer two questions: (1) how would responses of groups and individuals vary when they are the source of aggression? and (2) would responses vary when the target of aggression is a group versus an individual?

The purpose of the current experiment was to compare group and individual aggressive actions toward other groups and individuals. Four types of interactions were investigated: intergroup, interindividual, group-to-individual, and individual-to-group. Aggressive behavior was measured by the amount of hot sauce a group or individual allocated for another group or individual to consume.

Although hot sauce allocation is a somewhat novel measure of aggressive behavior, it has been used in several studies (e.g., Harmon-Jones & Sigelman, 2001; Kirkpatrick, Waugh, Valencia, & Webster, 2002; Lieberman, Solomon, Greenberg, & McGregor, 1999; McGregor et al., 1998). McGregor et al. (1998) first used hot sauce allocation to assess aggression and found that individuals who had their worldview threatened gave significantly more hot sauce to the target (individual believed to have threatened them) compared to individuals who were not threatened. In another study by McGregor et al. (1998), individuals participated in a bogus personality and taste study. These participants received either a noxious or neutral tasting juice which they believed was given to them by another participant, but was really given by a confederate. Participants who received the noxious juice reciprocated with significantly more hot sauce than those who received the neutral juice.

McGregor et al. (1998) defend their hot sauce paradigm by noting a case in which a cook laced the food of two policemen with Tabasco sauce. The policemen complained of pain, and the cook was subsequently arrested for assault. In other cases, parents and guardians have been charged with child abuse for force feeding hot sauce to their children (39-Year-Old Charged, 1992; Castanded, 1998; Formal arraignment, 1997), and a man was charged with torture for force-feeding his children cooked cockroaches with hot sauce (Father Indicted, 1996). These “real world” cases and prior studies suggest that hot sauce allocation and consumption can be thought of as inflicting harm upon an individual who would rather avoid this harm (i.e., the definition of aggression used in this paper; Baron & Richardson, 1994).

Three hypotheses were tested: (1) more hot sauce would be allocated in intergroup interactions as compared to interindividual interactions; (2) overall, groups would allocate more hot sauce than individuals; and (3) overall, more hot sauce would be allocated to groups as compared to individuals. If hypothesis one is supported, either hypothesis two or three may be supported to produce the effect for hypothesis one. However, it is possible that an interaction alone could produce results supporting hypothesis one. Therefore, hypotheses two and three will add to the completeness of our understanding of the results. In addition to these hypotheses, the influence of diffusion of responsibility and trait aggressiveness as potential mechanisms was investigated.

Section snippets

Participants

One hundred and seventeen undergraduate male students (mean age=20.00, SD=3.37 years) participated in this experiment in exchange for extra course credit or $5.

Hot sauce allocation

Hot sauce allocations were weighed in grams (.01 increments) using a Mettler Toledo digital scale (model number B502). The interindividual–intergroup discontinuity comparison indicated that the amount of hot sauce allocated in the intergroup condition (M=92.87, SD=38.11) was significantly greater (60%) than the amount allocated in the interindividual condition (M=58.17, SD=28.40), F(1,24)=6.93, one-tailed p=.008, d=1.03.

To determine if hot sauce allocations differed by the source and target, a 2

Discussion

This experiment compared aggression committed by groups and individuals in four types of interactions: intergroup, interindividual, group-to-individual, and individual-to-group. There was clear support for the first hypothesis that more hot sauce would be allocated in intergroup interactions compared to interindividual interactions. This result suggests that aggression follows a pattern similar to that of competition in the interindividual–intergroup discontinuity research. Results related to

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    This report is based upon a master’s thesis (first author) submitted in partial fulfillment of the requirements for the degree of Master of Science in Psychology at North Dakota State University. We thank Michael Robinson, Kevin McCaul, Jim Council, and Kevin Thompson for their comments as part of the thesis committee. We also thank anonymous reviewers for their insightful comments and Warren Honkola for acquiring the hot sauce. A portion of this research was presented at the 15th Annual Convention of the American Psychological Society, Atlanta, GA. Preparation of this manuscript was supported by a dissertation fellowship from North Dakota EPSCoR (Experimental Program to Stimulate Competitive Research) to the first author and grants from the National Institute of Mental Health (1 R15-MH63734) and the National Science Foundation (BCS-9905397) to the second author.

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