Some Things Psychologists Think They Know about Aggression and Violence
Clark McCauley
Professor of Psychology, Bryn Mawr College; Co-Director, Solomon Asch Center for the Study of Ethnopolitical Conflict, University of Pennsylvania; HFG grantee
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There are two distinctions that are crucial in the psychology of aggression and violence. The first is impulsive vs. instrumental aggression, and the second is individual vs. group aggression. Conveying these fundamental concepts to students is essential for teaching the psychology of intergroup conflict and genocide, where the costs of human aggression are highest.

Impulsive Aggression Is Different from Instrumental Aggression

Psychologists understand aggression to be behavior aimed at harming another member of the same species, and most psychologists distinguish between impulsive and instrumental aggression. Impulsive aggression (also known as irritable, angry, or expressive aggression) is marked by strong emotion, especially anger, and is aimed at hurting another. Instrumental aggression is cooler and the hurt delivered to another is not an end in itself but only the means to some other end. Aggression in a mugging, for instance, is aimed at getting the victim's money; aggression against Saddam Hussein's Iraq is aimed at repelling an aggressor.

Of course a particular instance of aggression may involve both impulsive and instrumental aggression, as when a parent spanks a child for going into the street. The spanking may be aimed at keeping the child out of the street in the future (instrumental aggression), but it may at the same time express the parent's fear and anger in reaction to the child's danger and disobedience (impulsive aggression). Although pure cases of impulsive or instrumental aggression may be rare, it is often useful to ask about a particular case of aggression whether it is predominantly impulsive or instrumental. Studies of aggression in children, for instance, have found it useful to distinguish reactive (impulsive) from proactive (instrumental) aggression.

Sociologists and criminologists studying violent crime are also beginning to use this distinction. Psychopaths are individuals with defective emotions; they do not experience normal levels of shame, guilt, or fear. Possibly as a result of this defect, they also have weak and transitory social attachments; they treat other people as objects. Psychopaths show predominantly instrumental aggression, as they use aggression coldly, as a means of controlling others. They are likely to continue aggressive acts despite conviction and punishment, and they are over-represented in prison populations.

Compared with instrumental aggression, impulsive aggression may be more easily deterred, or at least recidivism is less for crimes involving anger. A man who kills in anger in a bar brawl is less likely to kill again than a man who kills in the conduct of a robbery. Similarly, it appears that men who assault their female partners or their children in anger are more likely to quit than those who use aggression coldly, as a means of controlling those around them. There is also evidence that impulsive aggression, but not instrumental aggression, is related to low levels of serotonin in the brain.

If impulsive aggression looks like the lesser of two evils, it may be because anger, like shame and guilt, is a moral emotion. Aristotle said that anger is a reaction to insult—a specific form of moral violation. Modern frustration-aggression theory says that anger is a reaction to any noxious experience, including frustration. However, frustration-aggression theory recognizes the importance of moral violation as justifying the expression of anger and aggression. Further indication of the importance of moral violation in anger and aggression is provided by survey data indicating that the most common occasions of anger are perceived infringements of authority or independence, or other threats to positive self-image. Aristotle and modern psychology are agreed in seeing moral violation at the center of anger and impulsive aggression.

Group Violence Is Different from Individual Violence

The psychology of individual aggression is importantly different from the psychology of intergroup conflict. In general terms, it is the least socialized who are disproportionately involved in individual violence, whereas it is often the best socialized who are involved in intergroup violence.

Individual violence is represented in the statistics of violent crime: murder, robbery, assault, and rape. Although violence associated with organized crime groups and youth gangs makes some contribution to these statistics, the overwhelming majority of violent crime offences are individual offences. Violent crimes are committed disproportionately by individuals of lower socioeconomic status—individuals poorer and less educated than average. These are often individuals who do not accept the larger societal norms that give to the state a monopoly of the use of violence. Their weak socialization may be more cultural than personal, that is, the individual may be part of a deviant subculture in which violence is more acceptable than it is in the dominant culture. Still, from the point of view of the state and its norms, violent crime is predominantly a problem of undersocialized individuals.

In contrast, intergroup violence depends upon the leadership and example of well-socialized individuals. The prototype of intergroup violence is the violence of interstate war, and studies of U.S. and Israeli soldiers show consistently that the best soldiers are above average in civilian qualifications. Despite the many films based on a "dirty dozen" of career criminals forged into an effective combat team, the reality is that success in modern war depends on soldiers with middle-class levels of intelligence and education, multiplied by entrepreneurial virtues of initiative and cooperation. As war becomes more complex, success depends more on having good people up front.

The crucial role of well-socialized individuals is evident particularly in the extent to which good people do bad things in the name of the state. It was not the worst but some of the best of American boys who dropped firebombs on Dresden, Hamburg, and Tokyo and atom bombs on Hiroshima and Nagasaki. It was no less obvious then than now that, in time of war, city bombing is killing mostly noncombatants—old people, women, and children. Similarly, studies of police and military torturers reveal these individuals to be unremarkable except perhaps for a stronger-than-ordinary sense of duty and respect for authority.

Thus it is the least socialized who are disproportionately involved in individual violence, whereas the best socialized are the foundation of intergroup violence. The distinction is important because the origins of individual violence are mostly to be found in individual differences that tell us little about group conflict. Rather the origins of group conflict are in the power of group dynamics, and the origins of genocide are in the power of the state.

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