[Archived] The Development and Socialization of Aggression During the First Five Years of Life

University of Chicago, USA

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We socialize children to unlearn their aggressive behaviour patterns during the first years of life. In fact, one could argue that the reason most children do not develop problems with aggression is because they are presented with opportunities to experience intense negative emotions as infants, engage in aggression as toddlers, and are discouraged in various ways from repeating unacceptable behaviour. Very early in life, social contexts allow children to develop strategies that increase their capacity for emotional regulation and serve as adaptive alternatives to aggression. When significant impediments prevent children from developing such strategies, they develop sub-optimal emotional and behavioural functioning, resulting in considerable deficits in their social relations with caregivers and peers. Preschoolers who fail to develop age‑appropriate strategies for regulating their aggressive behaviour are at high risk for subsequent chronic antisocial and aggressive behaviour.


There is no question that the first five years of life comprise developmental experiences that are significantly challenging for children and caregivers alike. Several major sociobehavioural and cognitive shifts occur in children during this period, including the development of self-control and the capacity to tolerate frustration. The emergence of increasingly sophisticated verbal skills, self-awareness, and goal-oriented behaviour contribute to a strong push for independence in children. At the same time, parents begin to impose rules and limits, both in response to their children’s newfound autonomy and as a natural part of the socialization process. Clashes between a child’s self-assertions and a parent’s limit-setting efforts lead to more frequent episodes of frustration and upset. Thus, some degree of aggressive behaviour is fairly common in early life. How we differentiate normative from non-normative manifestations of aggression is therefore a clinically relevant and scientifically necessary goal for etiologic research and the prevention of violence.


Defining problematic development of aggression during the preschool years has been a controversial undertaking.1 To be precise, there is a fear of using developmentally inappropriate labels or concepts. Indeed, literature in the field of developmental and abnormal psychology defines aggression in very broad terms,2 describing a set of behaviours that range from typical and adaptive to atypical and maladaptive. But science and policy professionals require more concise, consistent definitions of atypicality. At a scientific level, comparability across studies is critical and requires clear definitions of severe problem behaviour. At a policy level, many professionals are concerned about pathologizing behaviour that is developmentally normal. Despite these issues of controversy, preschool children who manifest severe problem behaviour are at high risk for continued problem behaviour and are in need of services.

Research Context

We now have empirical data on the early emergence and the high rate of aggression in normative samples. Landy and Peters3 have reported manifestations of aggression in response to intense emotions (eg, the pulling of hair) in infants at 5 months of age. According to Tremblay and colleagues,4 at 17 months, close to half of the children they studied reportedly pushed others and 25% kicked others.

Recently, efforts to understand the etiology of serious aggression and antisocial behaviour in school-age children and adolescents have generated studies of atypical aggression in young children. These studies point to early childhood as a period during which deficits, which may be critical to establishing a foundation for aggressive behaviour, first emerge.5

Recent Research Results

A number of recent studies have established fairly consistent definitions of atypical aggression in early childhood. For example,Keenan and Wakschlag6 assessed the frequency, severity, and pervasiveness of conduct symptoms in clinic‑referred preschoolers. The most common symptoms they found were starting fights, bullying, and using objects to hurt others. These studies established age‑atypical levels and forms of aggressive behaviour.

Early behavioural problems have also been shown to be relatively stable over time, thus establishing that atypical behaviours are not necessarily transient and do not merely reflect normal developmental perturbations. Campbell and associates7 reported that preschoolers identified as “hard to manage” had significantly more behavioural problems, including aggression, than matched controls by the time they reached school age. Keenan et al8 demonstrated that aggression observed at 18 months was significantly correlated with DSM-III-R externalizing disorders at age 5. Indeed, young children who manifest severe and pervasive forms of aggression demonstrate significant levels of social impairment and are therefore significantly more likely to develop subsequent mental health problems.

The socialization of aggression comprises a broad spectrum of processes. Ideally, it begins with caregiver responsiveness early in life and expands to include the socialization of behavioural control, empathic responses, and problem-solving skills. Inappropriate responsiveness from caregivers to emotional and behavioural dysregulation in young children appears to increase the risk of subsequent problems with aggression. Inappropriate responsiveness includes under-responsiveness (passive or detached reactions) and over-responsiveness (harsh reactions). For example, Shaw, Keenan, and Vondra9 reported that the absence of maternal responsiveness to a demanding infant was predictive of disruptive behavioural problems at age 3. Bates et al10 assessed outcomes of difficult and non-difficult preschoolers in the context of authoritative and passive parents. By late childhood, the difficult preschoolers with passive parents had the worst outcomes in terms of subsequent parent- and teacher-rated externalizing problems. Campbell and colleagues7 reported that observations of negative maternal control and maternal self‑reports of negative discipline techniques at age 4 predicted externalizing problems by age 9, even after controlling for earlier behavioural problems.

The study of the effect of socialization practices on young children has also revealed interesting sex differences. Indeed, at the end of the preschool period, rates of aggression are typically lower in girls than they are in boys.11 Smetana12 observed that mothers responded to their daughters' transgressions by pointing out the consequences that the transgression would have on their peers, whereas mothers of boys responded with punishment. By age 3, boys engaged in twice as many transgressions as girls. Ross and colleagues13 reported that the mothers of boys supported their own children in the context of peer conflicts three times as often as did the mothers of girls. Furthermore, mothers tended not to support their daughters when their rights of ownership had been violated.

Overall, current data on parenting indicates that a child is at greater risk of developing aggressive behaviour when his or her caregiver responds in developmentally inappropriate ways, especially when the child already presents a difficult temperament. Moreover, the same data indicates that there may be a mechanism that causes rates of aggression in boys and girls to diverge during the first five years of life.


Aggression develops early in life.  Thus, the socialization of aggressive behaviour also begins early. Although most children learn to inhibit aggressive behaviours, some engage in aggression that is pervasive, frequent, and severe. The debate continues as to how early disruptive behavioural problems, including aggression, might best be conceptualized. When aggressive behaviours interfere with a child’s developmental functioning to the degree that he or she is asked to leave a preschool, is being aggressive towards caregivers, or is not able to maintain a prosocial relationship with a peer, there appears to be a growing consensus that such behaviours should be deemed atypical. However, it is important to develop methods for adequately and reliably assessing early emotional and behavioral dysregulation so that a child does not have to wait to experience a significant developmental failure to receive services.

Implications for Policy and Services

Scientists in the field of developmental psychopathology have been presented with a vital opportunity to advance policy regarding the mental health of children. Further research should be conducted regarding factors that may emerge as early as infancy, factors that may place children at risk for subsequent behavioural and emotional problems. This type of research can only help build political momentum for future applications in developmental psychopathology. Current data indicate that most children desist from behavioural problems. Therefore, the preschool period may be viewed as the best time to encourage prosocial behaviour in children and inculcate optimal patterns of response for healthy social development. However, developmental studies of child and parent behaviour should start during pregnancy so that environmental factors may be examined individually and interactively over time. This approach to research acknowledges the tremendous potential for change in early childhood. It may also yield an improved approach to guiding children’s developmental pathways in more positive directions.


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How to cite this article:

Keenan K. [Archived] The Development and Socialization of Aggression During the First Five Years of Life. In: Tremblay RE, Boivin M, Peters RDeV, eds. Tremblay RE, topic ed. Encyclopedia on Early Childhood Development [online]. https://www.child-encyclopedia.com/aggression/according-experts/development-and-socialization-aggression-during-first-five-years-life. Published: June 2002. Accessed May 27, 2024.

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