Many aggressive children and adolescents have grown up in violent homes and neighborhoods (environmental factors), but some became violent for other reasons, such as the student shootings at Columbine High School and other schools. Studies on the causes of aggression in children and adolescents have reported that in general there is no one single cause of aggression.
When this study was started, the focus in the aggression literature was on the environmental causes/risk factors of aggression, with little emphasis on psychological and personality traits. This study attempts to delve into some of these issues while also revisiting the environmental factors as a cause of aggression and violence.
The seven-year study showed that two characteristics strongly predicted the development of aggression: 1) physical punishment/ aggression by parents against the children, and 2) inhibited temperament of the child (child withdraws from unfamiliar situations, people, or environments).
The most powerful factor was parents’ physical punishment and violence in the home. Inhibited temperament was the only personality characteristic that predicted aggression, which suggests possible connections with the isolated, alienated children and adolescents who have committed school attacks. The important factors for predicting aggression seemed to be fearfulness in general and apprehension/lack of confidence about school, not simple shyness. Inhibited children in this study were characterized as socially withdrawn, uncomfortable or distressed in new situations, and anxious about making new friends or trying new activities. Inhibited children may react to problems with peers and schools by making negative attributions against others, which makes acting aggressively towards others more likely.
Examples of aggressive behavior included fighting and lashing out at their peers both physically and verbally, insulting them, hitting and pushing them, attacking them with weapons, and, in extreme cases, criminal aggression, including murder.
In summary, the following factors did predict aggression:
1. Harsh physical punishment in the family
3. Peer victimization predicted aggressive fantasy, and aggressive fantasy predicted amount of aggression
4. Low self-esteem predicted amount of aggression, but not as strongly as the other factors
Although aggression increased with age as expected, the effect of socioeconomic status, race, ethnicity, or gender had little effect on predicting violence.
In summary, the following factors did not predict aggression:
2. racial and ethnic group
3. socioeconomic status sensation seeking—boys and older children were higher sensation seekers, but sensation seeking did not predict aggression
Findings indicate that most of the study children were not very aggressive, fitting national norms. Specifically, 25 out of the 440 children in the original sample were above the clinical line on the CBCL. So far, two children have been jailed for severe criminal aggression, including murder.
Representative sampling was conducted to include 440 children between the ages of 7 and 13 in Springfield, Massachusetts, a small city which has a population similar to national norms and represents a microcosm of the diversity and problems found in the U.S. Certain zip codes were oversampled to obtain equal numbers of Caucasians, African Americans and Hispanic/Latinos. An approximately equal number of male and female and Hispanic/Latino, Caucasian and African-American children were included from all socioeconomic levels. Assessment began at 7 to 13 years and has continued in four waves to 12 to 18 years of age.