Page 1Page 2Page 3Page 4Page 5Page 6Page 7Page 8Page 9Page 10Page 11Page 12Page 13Page 14Page 15Page 16Page 17Page 18Page 19Page 20Page 21Page 22Page 23Page 24Page 25Page 26Page 27Page 28Page 29Page 301The Development of Aggression in Early ChildhoodDaniel S. ShawAll correspondence should be directed to the first author using the following contactinformation:Mailing address: Department of Psychology, 210 South Bouquet Street, 4101 Sennott Square,University of Pittsburgh, Pittsburgh, PA, 15260-0001Telephone number: 412 624-1836E-mail: [email protected]: 412 624-8827AcknowledgmentsMuch of the research reported in this paper was supported by grants to the author from theNational Institute of Mental Health, grants MH 50907, MH 01666, and MH 03876. I am gratefulto the work of the staff of the Pitt Mother & Child Project and the Pitt Early Steps Project fortheir years of service, and to our study families for making the research possible. This work wasalso greatly influenced by my colleagues Thomas Dishion, Frances, Gardner, and the lateRichard Bell. Finally, much of the material for this chapter originally appeared in the followingvolume: Shaw, D.S., Gilliom, M., & Giovannelli, J. (2000). Aggressive behavior disorders. InC.H. Zeanah (Ed.), Handbook of Infant Mental Health, 2nd Edition (pp. 397-411). New York:Guilford. Chapter to appear in H. E. Fitzgerald, B. M. Lester & B. M Zuckerman (Eds). (Inpress). The Crisis in Youth Mental Health, vol. 1. The organization and prevention of children’smental health problems. Greenwood Publishing Group, Inc.2IntroductionRecent consideration of developmental trends in the onset of antisocial behavior has beenfocused on children who show a persistent course of conduct problems beginning in earlychildhood. Termed ‘early starters,’ such individuals have been found to show a persistent andchronic trajectory of antisocial behavior extending from early childhood to adulthood. Earlystarters represent approximately 6% of the population, yet are responsible for almost half ofadolescent crime and three-fourths of violent crimes (Offord, Boyle, & Racine, 1991). During the past two decades, researchers have become increasingly interested in thepossibility that early-starting children can be identified at younger and younger ages. In the1980's, studies were initiated during the preschool and school-age periods (Campbell, Pierce,Moore, Marakovitz, & Newby, 1996), while during the past decade predictors of early-startingpathways have been established beginning in the toddler period (NICHD Early Child CareResearch Network, 2004). Longitudinal studies initiated during the toddler and early preschoolperiods have identified a group of early-starter children who go on to show the most chronic andsevere forms of antisocial behavior. Despite the potential advantages of identifying early-startingchildren before reach school-age, there are potential pitfalls to this approach. These include:! Intentionality, an important component of aggression and other forms of disruptivebehavior, is difficult to infer among infants and young toddlers.! Most children do not have the cognitive capacity to comprehend aggression fully untiltheir 3rd or 4th year.! For most children who show aggressive behavior prior to age 3, it is likely to betransient.! Age 2 represents the peak incidence rate of aggressive behavior during the life course3(Tremblay, 1998), which means that the probability for predicting those children whowill likely desist from showing high rates of aggression in the future is likely to be high(i.e., false positives). ! Many children who are aggressive at age 2 will find alternative conflict resolutionstrategies to replace its use by age 4 or 5. Alternatively, the following points support the identification and use of preventiveinterventions with such children.! Children who are not aggressive during the toddler period are unlikely to developclinically-elevated levels of aggressive behavior in later childhood or adulthood. ! Very few children begin showing high rates of physically aggressive behavior after age 5.! Toddlers have the capacity to inflict serious harm on siblings, parents, pets, and objects.! Predictors of aggression and other forms of disruptive behavior are similar throughoutearly and later childhood.! Interventions targeted at younger children have been shown to be more efficacious thanthose used with older school-age children and adolescents.Despite caution being warranted, it is believed that work identifying factors associatedwith early-starting pathways of aggression and its prevention is merited, particularly given thegreater malleability of children’s behavior and parent-child relationships in early childhood.Thus, the present chapter reviews factors associated with early-starting pathways, and preventiveinterventions initiated during early childhood that have been associated with the prevention ofsuch trajectories, including basic and applied studies from the author’s own laboratory. From asocietal perspective, as the greatest concern is associated with the prevention of physicallyaggressive behavior, much of the emphasis is on the development and prevention of aggressive4behavior versus other types of disruptive problem behavior, including oppositionality andhyperactivity. However, as these behaviors tend to co-occur throughout childhood, mostresearch on the identification and treatment of antisocial behavior has aggregated togetherreported on multiple forms of disruptive behavior.Defining AggressionIntentionality lies at the heart of more recent definitions of aggression. It is perhaps theprimary reason for some researcher’s dismay at using the term ‘aggression’ to describeaggressive-like behavior during infancy and the early toddler period (i.e., ages 1 to 3). Earlydefinitions of aggression varied. Some investigators focused solely on outcome, while othersestablished intent to injure another person as the primary criterion. More recent interpretationsassume an intent to at least threaten another and a consensus that the behavior be viewed asaggressive by the aggressor, the victim, and society. For purposes of the present discussion,aggressive behavior will be defined as an act directed towards a specific other person or objectwith the intent to hurt or frighten, for which there is a consensus about the aggressive intent ofthe act. Aggressive acts toward others are typically sub-divided into two