Development Of Aggression And Related Problem Behaviors In Childhood And Their Risk And Protective Factors In Family Context

Human aggression has been an important theme of research since the beginning of psychology and has been extensively studied by researchers with different theoretical perspectives. In the discipline of developmental psychology, research on children's aggression can be traced back to the early thirties of the 20th century. Ever since then, the development and control of agreesion have been among topics that received the most attentions of researchers for more than half a century [1-2]. Especially in recent years, with violence has been recognized as a primary and increasingly important public health priority [3], research on development and treatment of aggression and other forms of antisocial behaviors has been further promoted and kept constantly growing.Among other things, the study of the development of aggression in the last several decades has primarily involved the developmental patterns of aggressive behaviors, the relationship between aggression and children's social adjustments, and the intra-child and contextual factors of aggression. Although the large amount of research literature has shed much light on these themes, there are several important issues that need further clarifications and investigations, including the individual differences not only in the average level but also in the developmental pattern of aggression, the comorbidity of aggression and other problem behaviors, and the gender differences in the average level and the developmental courses of aggreesion. Besides, the existing conclusions of the related contextual risk factors and protective factors of children's aggressive behavior are in most part from cross-sectional studies and lacked clear conceptual framework. These finding should be solidified via longitudinal design within a clear theoretical framework.This doctoral thesis was designed to examine the development of aggression and related problem behaviors and their risk and protective familial factors using a longitudinal design and a retrospective design respectively. Analysis of data focused on: (1) the development of aggression from early childhood to preadolescence, including the age-related pattern of aggression in different ages, stability of individual differences, and the developmental trajectories or subgroups; (2) the development of externalizing and internalizing behaviors from early childhood to preadolescence, including the age-related pattern of problem behaviors in different ages, stability of individual differences, the developmental trajectories of subgroups, and the comorbidity of aggression and externalizing and internalizing behaviors; (3) gender differences in the development of aggression and problem behaviors as manifested in the average level of both sex and also in the developmental trajectories and stability; (4) the related risk factors and protective factors in children's family context, including the demographic characteristics, maternal parenting, and family environment.200 children from four kindergartens in Jinan City, Shandong Province were included in the longitudinal study. For the longitudinal sample, children's aggression was assessed in an interval of half a year using natural observation from age 3 to 6 and in an interval of a year using peer rating when children were 7 to 9 years old. Teachers rated children's externalizing and internalizing behaviors at age 4, 6, 7, and 8, and mothers reported the family demographic characteristics, parents'maternal parenting, and family environment at age 4, 5, 8, and 9. In the retrospective study, 700 children of grade 6 from four primary schools in Jinan City, Shandong Province were included. Children's aggression and problem behaviors were rated by the head teachers who had ever been in charge of the classes from grade 1 to 6. Data of children's family demographic characteristics, maternal parenting, and family environment were collected via mother report.The main findings of the study were as follows: 1. In the group level, children's physical aggression decreased dramatically from age 3 to 6, and increased slightly or kept relatively stable during the transition from kindergarten to primary school, and then decreased steadily in late childhood. Verbal and relational aggression increased consistently in the childhood.2. There were individual differences in the development of aggression. Compared to verbal and relational aggression, physical aggression showed much more obvious individual variations in developmental courses, and 3 theoretically significant developmental trajectories were identified from early childhood to preadolescence. The stability of individual differences in the level of physical aggression was evident from early childhood onward. The development of verbal and relational aggression also showed differential development for different individuals. From middle childhood on, the stability of individual differences in the levels of verbal aggression and relational aggression became significant.3. Remarkable gender differences emerged in both the level and developmental courses of physical aggression and verbal aggression. Boys showed higher level of aggression than girls. They were more likely than girls to be involved in the developmental trajectories of higher aggression, and the stability of individual differences of physical and verbal aggression among boys was more evident than among girls. Such gender differences in aggression existed from early childhood. In the case of relational aggression, the gender differences were not significant, neither in terms of the group level nor in the developmental course.4. The development of externalizing behaviors manifested similar developmental patterns as those of aggression, and its level decreased systematically from early childhood to preadolescence. The average development of internalizing behaviors showed first a decrease from early childhood to middle childhood, then an increase in the transition to late childhood, and thereafter a decrease in preadolescence.5. Significant individual differences of externalizing behaviors were found, with theoretically significant developmental trajectories (4 developmental subgroups in the longitudinal sample and 2 subgroups in the retrospective sample) being identified from early to late childhood. The individual differences in the level of externalizing behaviors kept quite stable in childhood. The development of internalizing behavior also showed certain individual differences, and compared to that in early childhood, the individual variations of internalizing behaviors were more evident in middle and late childhood.6. There were gender differences in the average level and developmental courses of externalizing behaviors, with boys showing higher level of externalizing behaviors and being more likely to be involved in high externalizing behavior trajectories. No significant gender difference in internalizing behaviors was found.7. There were obvious comordity of aggression and other externalizing behaviors, which were reflected in the significant correlations between aggression and externalizing behaviors and the higher likelihood of children in high aggression trajectories to get involved in high externalizing developmental trajectories. Children's aggression was found to be associated anxiety, but associations between aggression and other internalizing behaviors were not significant.8. Children from lower SES families were found to be more likely to show aggression and other externalizing behaviors than children from high SES families. Children whose parents were in the lower class of occupation were more likely to experience internalizing behaviors. From middle childhood on, children with parents of less education became more likely to experience internalizing behaviors. These results indicated that low SES as reflected in lower class of parents'occupation and less education was a consistent risk factor in the development of children's aggression and problem behaviors.9. The retrospective study revealed the effect of family income on the development of aggression and related externalizing behaviors, indicating that family economic press was a risk factor in the development of children's aggression and related externalizing behaviors.10. Positive parenting and the dimensions of family environment were associated negatively with children's aggression and problem behaviors, indicating that positive parenting and favorable family atmosphere can serve as protective factors for children. Negative parenting was positively correlated with aggression and externalizing behaviors, suggesting that mother's punishment and control were risk factors in the development of aggression and other externalizing behaviors.