Journal Issue: Children and Electronic Media Volume 18 Number 1 Spring 2008
Aggressive and Violent Behavior
Aggression is usually defined by behavioral scientists as behavior that is intended to harm another person. Common forms of aggression are physical (for example, punching), verbal (for example, saying or writing hurtful things to another person), and relational (for example, intentionally and publicly not inviting someone to a party to harm his social relationships). Violence usually is conceived as more extreme forms of physical aggression that are likely to result in physical injury. The most extreme form of violence is homicide, but any form of aggressive behavior that is likely to result in an injury serious enough to warrant medical attention is considered violence. Thus, fights involving weapons as well as fistfights by adolescents old enough to be able to inflict serious injuries are considered acts of violence.
The relation of these terms to violent “crime” requires some comment. The vast majority of media violence research focuses on aggressive and violent behavior as defined earlier. Violent crime is a much more restrictive category and is applied only in cases where someone has been arrested for a crime classified by police as a major crime against persons, such as murder, rape, and assault. There are at least two reasons for the discrepancy between the behavioral scientists' focus and the criminologists' focus. First, the criminological focus is based more heavily on the consequences of a specific action, whereas the behavioral science focus is almost exclusively based on the intention behind the action. Understanding the causes of violent behavior requires this focus on intentions rather than on whether the person succeeded in harming the individual and was subsequently caught. Second, not only is it much more difficult and expensive to do research on violent crime because it is relatively rare (thereby requiring huge sample sizes), but also certain types of research, such as experimental studies, would be unethical. For these reasons, we focus on aggressive and violent behavior, though we cite violent crime data where useful.
Violent Behavior: The Scope of the Problem
Youth violence resulting in deaths and injuries has direct and indirect costs in excess of $158 billion each year. Only accidental injury (frequently auto accidents) consistently leads homicide as the cause of death of U.S. youths between one and twenty-four years of age.113 For youths between the ages of ten and twenty-four, homicide is the leading cause of death for African Americans, the second leading cause for Hispanics.114
Young people not only suffer but also commit a disproportionate share of violence. Although twelve- to twenty-year-olds made up about 13 percent of the U.S. population in 2005, they were responsible for some 28 percent of the single-offender and 41 percent of multiple-offender violent crimes.115 Figure 5 displays the overall U.S. assault rates and six twelfth-grade violence prevalence rates between 1982 and 2003. U.S. assault rates rose dramatically from the early 1980s to the early 1990s and then, just as dramatically, fell. Other overall rates for violent crime, such as homicide, show the same pattern. One factor that likely contributed to this rise and fall was changes in the share of the U.S. population in the high-violence age range.
Although rates of youth violence also increased during the late 1980s and early 1990s, they have not fallen in recent years. In fact, the youth violence indicators in figure 5 show considerable stability over time; several appear to be increasing.116
Media Exposure and Aggressive and Violent Behavior
The extent to which media violence causes youth aggression and violence has been hotly debated for more than fifty years. Despite many reports that exposure to violent media is a causal risk factor, the U.S. public remains largely unaware of these risks, and youth exposure to violent media remains extremely high. Among the public advisories that have been generally ignored are congressional hearings in 1954, U.S. surgeon general reports in 1972 and 2001, a National Institute of Mental Health report in 1982, and a Federal Trade Commission report in 2000. In addition to government studies, reports have been issued by scientific organizations such as the American Psychological Association (in 1994, 2000, and 2005), the American Academy of Pediatrics, the American Academy of Child and Adolescent Psychiatry, the American Medical Association, the American Academy of Family Physicians, and the American Psychiatric Association.
The most recent thorough review of the research on media violence, by an expert panel convened by the U.S. surgeon general, concluded, “Research on violent television and films, video games, and music reveals unequivocal evidence that media violence increases the likelihood of aggressive and violent behavior in both immediate and long-term contexts.”117 Hundreds of original empirical studies of the link between media violence and aggression have been conducted, and numerous reviews of those studies—both narrative and statistical—have come to the same conclusion. Indeed, one analysis found clear evidence that exposure to media violence increases aggressive behavior as early as 1975.118
The newest form of media violence—violent video games played on computers, video game consoles, handheld systems, the Internet, and even cell phones—also is the fastest growing. Although most youth still spend more time each week watching TV, including movies, than playing video games, the time they spend with video games is increasing rapidly, and a growing share of youth is spending many hours playing video games. For example, about 90 percent of U.S. youth aged eight to eighteen play video games, with boys averaging about nineteen hours a week.119 Annual surveys of college freshmen over time reveal that as twelfth graders they spend ever-increasing amounts of time playing video games. The finding is especially true for boys, as shown in figure 6.120
We review evidence on the link between youth violence and violence on television and film and on video games. We could find no studies on the effects of violence in advertising on aggressive or violent behavior, but the effects of such violent content are likely to be similar.
Television and Movie Violence and Violent Behavior
Television and movie violence are the most extensively researched forms of media violence. Studies using all three major research designs have all reached the same conclusion—exposure to television and movie violence increases aggression and violence.
Experimental studies have shown that even a single exposure increases aggression in the immediate situation. For example, Kaj Bjorkqvist randomly assigned one group of five- to six-year-old Finnish children to watch violent movies, another to watch nonviolent ones. Raters who did not know which type of movie the children had seen then observed them playing together in a room. Children who had just watched the violent movie were rated much higher on physical assault and other types of aggression.121 Other experiments have shown that exposure to media violence can increase aggressive thinking, aggressive emotions, and tolerance for aggression, all known risk factors for later aggressive and violent behavior.
Many cross-sectional studies have examined whether people who view many violent TV shows and movies also tend to behave more aggressively. Such studies generally find significant positive correlations. For example, one group of researchers studied the links between “aggressive behavioral delinquency,” such as fighting and hitting, and TV violence viewing in samples of Wisconsin and Maryland high school and junior high school students. They found significant positive links between TV violence exposure and aggression for both boys and girls.122 Another research team reported 49 percent more violent acts in the past six months by heavy viewers of TV violence than by light viewers.123
Researchers also have used longitudinal studies to investigate television violence effects, using time periods that range from less than one year to fifteen years. One research team studied a group of six- to ten-year-olds over fifteen years. They found that both boys and girls who viewed television violence committed more aggression (physical, verbal, and indirect) during young adulthood. The study found the same link when the outcome examined was outright physical violence, such as punching, beating, choking, threatening, or attacking with a knife or gun. This media violence study is one of the few to include measures of violent crime. Because it is a well-conducted longitudinal study, it lends considerable strength to the view of media violence as a causal risk factor for aggression, violence, and violent crime. Interestingly, although frequent exposure to TV violence during childhood was linked to high levels of adulthood aggression, high aggressiveness during childhood did not lead to frequent viewing of television violence in adulthood.124
Violent Video Games and Violent Behavior
The most popular video games played by youth contain violence. Even children's games (as designated by the industry-sponsored Entertainment Software Ratings Board) are likely to contain violence. More than 30 percent of games rated “E” (suitable for everyone) contain a violence descriptor; more than 90 percent of “E10+” games (suitable for those ten years and older) contain a violence descriptor.125 About 70 percent of fourth to twelfth graders report playing “Mature”-rated games (suitable for those seventeen and older), which contain the most graphic violence of all.126
Research on video game violence is less extensive than that on TV and film violence, but the findings are essentially the same. Experimental studies in field and laboratory settings generally find that brief exposure to violent video games increases aggressive thoughts, feelings, and behavior. For example, one laboratory study assigned children and college students randomly to play either a children's video game that involved shooting cartoon-like characters or a nonviolent children's video game. Later, all participants completed a standard laboratory task that measures physical aggression. Those who had played the violent children's game displayed a 40 percent higher aggression rate than those who had played a nonviolent game. The effect was the same for both elementary school children and college students.127 In a field experiment, children were randomly assigned to play either a violent or nonviolent video game and then were observed by trained coders during a free-play period. The children who had played the violent game displayed significantly more physical aggression than those who had played a nonviolent game.128
To date, the only published longitudinal study that clearly delineates the possible influence of violent video games used a relatively short time span of six months. The researchers conducting the study assessed the media habits and aggressive tendencies of elementary school children, as well as a host of control variables, twice within a school year. The children who were heavily exposed to video game violence early in the school year became relatively more physically aggressive by the end of the year, as measured by peers, teachers, and self-reports.129 Cross-sectional studies have also found positive correlations between exposure to violent video games and various forms of aggression, including violent behavior and violent crimes.130
All three types of studies have also linked violent video games to a host of additional aggression-related cognitive, emotional, and behavioral outcomes. Outcomes include more positive attitudes toward violence, increased use of aggressive words or solutions to hypothetical problems, quicker recognition of facial anger, increased self-perception as being aggressive, increased feelings of anger and revenge motives, decreased sensitivity to scenes and images of real violence, and changes in brain function associated with lower executive control and heightened emotion.131
Violent Behavior: Summary
The research evidence shows clearly that media violence is a causal risk factor for aggressive and violent behavior. There is considerably less evidence concerning violent crimes, but the few cross-sectional and longitudinal studies that included violent crime measures also found similar links with media violence. The size of the media violence effect is as large as or larger than that of many factors commonly accepted by public policymakers and the general public as valid risk factors for violent behavior. Figure 7 illustrates the current best estimates of several risk factors for youth violence. The figure does not include the longitudinal violent video game effect because the one relevant study did not include a specific measure of violence that is comparable to the other factors. However, several studies have directly compared video game and TV violence using the same participants and the same measures; they generally find a somewhat larger effect for video games. Thus, we expect that the effect of violent video games on long-term violence will be larger than that of TV violence and smaller than that of gang membership. Furthermore, it is likely that overall media violence exposure has a somewhat larger effect than any individual type of media violence. In any case, the figure makes clear that media violence exposure has a larger effect on later violent behavior than does substance use, abusive parents, poverty, living in a broken home, or having low IQ.132