Reactive and proactive aggression: evidence of a two-factor model

This article examines the construct validity of reactive and proactive aggression, as assessed by the teacher-rating scale developed by K. A. Dodge and J. D. Coie (1987). In Study 1 (n = 149 boys), confirmatory factor analyses revealed that a 2-factor model, in which a substantial correlation was observed between the 2 latent factors, presented a better fit than a single-factor model. Study 2 (n = 193 boys) examined the relations presented by the 2 forms of aggression with peer status, leadership, social withdrawal, and victimization by peer. Reactive and proactive aggressive behaviors presented distinct patterns of relations consistent with the theoretical definitions. The results of these studies suggest that the questionnaire measures 2 forms of aggressive behavior that, although being substantially related, have a unique discriminant dimension.     

Physical aggression and expressive vocabulary in 19-month-old twins

In the prevention of physical aggression, possible etiological links with language development are rarely taken into account. Indeed, little is known about when language and aggressive behavior become linked during development and which mechanisms are responsible for this association. This study investigated the association between physical aggression and language in late infancy with a genetic design that involved 562 19-month-old twins. A modest but significant correlation (r = -.20) was found between physical aggression and expressive vocabulary. Substantial heritability was found for physical aggression. Quantitative genetic modeling suggests that the correlation between expressive vocabulary and physical aggression cannot be explained by shared etiologies. However, phenotype-to-phenotype models indicate that the covariation can be entirely accounted for by a significant phenotypic path from expressive vocabulary to physical aggression. The implications of these results for early prevention of chronic physical aggression are discussed.     

The evolution of problem and social competence behaviors during toddlerhood: A prospective population‐based cohort survey

Research in developmental psychopathology has long been preoccupied with rather broad categories of behavior, but we know little about the specific behaviors that comprise these categories. The objective of this study was to: (a) estimate the prevalence of problem and social competence behaviors in the general population of children at 17 months of age, and (b) describe the continuity and discontinuity in the degree to which children exhibit these behaviors between 17 and 29 months of age. The results show that frequent problem behaviors are not typical of children under two years of age. Further, the results suggest that it is possible to distinguish between different types of problem behaviors before two years of age. In addition, the results show that gender differences in some problem behaviors are already present before two years of age, and increase in magnitude during toddlerhood. Finally, the results show that interindividual differences in problem behaviors observed before two years of age are stable. The predictive accuracy of frequent problem behaviors in children at 17 months of age was limited, however, with often a majority of toddlers not behaving this way a year later. Overall, our results suggest that toddlerhood represents a critical period when behavioral and emotional problems of potentially clinical significance emerge. Pediatricians should routinely ask parents to report the frequency of their young children's problem behaviors during child health supervision visits so that children whose frequent problem behaviors persist over time can be identified and possibly referred for treatment.     

Do Friends’ Characteristics Moderate the Prospective Links between Peer Victimization and Reactive and Proactive Aggression?

This study examined (a) the predictive link between peer victimization and children’s reactive and proactive aggression, and (b) the potential moderating effect of reciprocal friends’ reactive and proactive aggression in this context. The study also examined whether these potential moderating effects of friends’ characteristics were stronger with respect to more recent friends compared to previous friends. Based on a convenience sample of 658 twin children (326 boys and 332 girls) assessed in kindergarten and first grade, the results showed that peer victimization uniquely predicted an increase in children’s teacher-rated reactive aggression, but not teacher-rated proactive aggression. The relation of peer victimization to increased reactive aggression was, however, moderated by recent ˉ not previous ˉ reciprocal friends’ similarly aggressive characteristics. These findings, however, tended to be mostly true for boys, but not for girls. The findings are discussed in terms of their theoretical and practical implications for victimized children’s risk of displaying reactive and proactive aggressive behaviors. This research was made possible by grants from the Social Sciences and Humanities Research Council of Canada, the Fonds Concerté pour l’Aide à la Recherche, the Fonds Québécois de la Recherche sur la Société et la Culture, the Canadian Institutes of Health Research, and the Fonds de Recherche en Santé du Québec.     

Gender differences in physical aggression: A prospective population-based survey of children before and after 2 years of age

There has been much controversy over the past decades on the origins of gender differences in children's aggressive behavior. A widely held view is that gender differences emerge sometime after 2 years of age and increase in magnitude thereafter because of gender-differentiated socialization practices. The objective of this study was to test for (a) gender differences in the prevalence of physical aggression in the general population of 17-month-old children and (b) change in the magnitude of these differences between 17 and 29 months of age. Contrary to the differential socialization hypothesis, the results showed substantial gender differences in the prevalence of physical aggression at 17 months of age, with 5% of boys but only 1% of girls manifesting physically aggressive behaviors on a frequent basis. The results suggest that there is no change in the magnitude of these differences between 17 and 29 months of age.     

分离遗传与环境对儿童发展的影响：介绍一个新颖的研究方法

本文介绍一个可以用于研究遗传与环境互动的新颖方法。此研究收集了上千个4~10岁儿童的数据。这些儿童的出生都借助于不同的辅助受孕技术（Assisted Reproductive Technologies）,包括试管婴儿、精子捐赠、卵子捐赠、胚胎捐赠及代孕技术。本项目通过妇科（助孕）医院收集被试的行为数据,包括家庭互动、养育方式、父母婚姻质量、家庭成员的心理健康及经济状况等。本文选择性地介绍一些分析的结果,以彰显这种设计在分离遗传和产前产后环境对儿童发展的贡献。首先,我们比较了“助孕”儿童与“自然孕”儿童在父母冲突、父母对子女敌意以及儿童抑郁症状之间关系的异同。其次,我们比较了这两组儿童在父母抑郁症状、家庭关系质量以及儿童抑郁症状之间关系的异同。再次,本文介绍了这一可分离遗传与环境因素的研究设计。最后,我们讨论了这一设计对发展心理病干预及预防的意义