AGGRESSIVE BEHAVIOR DISORDERS
The very title of this chapter raises concerns. At issue is whether it is appropriate to use the term "disorder" to describe children with significant levels of aggression between the ages of 1-3.
Those who have doubts about establishing an aggressive disorder of infancy, point to the following concerns.
Alternatively, the following points support establishing a disorder of aggressive behavior during infancy.
This chapter will explore issues surrounding aggressive behavior problems during infancy. To understand fully the complexities of this topic, we will review how the term "aggression" has been defined, its development and stability during early childhood, factors that influence its onset and maintenance, and current treatment approaches. Finally, a clinical case will be presented to demonstrate the techniques and challenges involved in implementing treatment.
Intentionality lies at the heart of more recent definitions of aggression. It is perhaps the primary reason for not using the term aggression to describe aggressive-like behavior during infancy. Early definitions of aggression varied. Some investigators focused solely on outcome (Buss, 1961), while others established intent to injure another person as the primary criterion (Dollard et al., 1939). More recent interpretations assume an intent to at least threaten another and a consensus that the behavior be viewed as aggressive by the aggressor, the victim, and society (Bandura, 1979). For purposes of the present discussion, aggressive behavior will be defined as an act directed towards a specific other person or object with the intent to hurt or frighten, for which there is a consensus about the aggressive intent of the act (Grusec & Lytton, 1988; Maccoby, 1980).
Aggressive acts toward others are typically sub-divided into two categories: hostile and instrumental aggression. Hostile aggression refers to instances in which the major goal is inflicting injury, whereas instrumental aggression involves using force or threat of force to achieve a nonaggressive end (e.g., obtaining an object or gaining territory) (Grusec & Lytton, 1988). Note that in both kinds of aggression, intentionality is considered to be salient in determining if a behavior is aggressive. This presents a challenge in judging whether an infant has acted aggressively because of his/her limited cognitive ability and an observer's inability to interpret the meaning of the behavior.
At issue in inferring aggressive intent is the child's developmental status. According to Maccoby (1980), a child must understand the following principles to carry out an intentionally hurtful act:
1. that the intended victim can help or hinder the child's goals, knows what the child wants the victim to do, and knows that the victim can experience distress;
2. that the child's actions can generate distress;
3. that specific actions can cause distress in specific individuals;
4. that the child can execute distress-producing actions;
5. that distress can cause the victim to act in ways the child desires;
6. that the victim's actions can serve the child's needs.
Maccoby stresses that the child need not be conscious of these principles to act aggressively, but must have some rudimentary understanding of each to act in a fully aggressive manner. At a broader cognitive level, the young child must be able to understand the nature of the other, including the other's goals and plans (Bowlby, 1969). Typically, a child develops the capacities to understand fully the point of view of another person at the beginning of the preschool years (Piaget, 1952); however, Dunn and Kendrick (1982) have found that some children under the age of 3 are capable demonstrating these capacities when interacting with younger siblings. Given that it would be unusual for a two year-old to understand the theoretical underpinnings of aggressive behavior, conservatism is warranted in interpreting the meaning of aggressive-like behavior, particularly from ages one-two. Just as 10-11 year olds who commit murder with firearms are treated as children because of their limited ability to understand the long-term consequences of their actions, infants who cause injury to siblings, parents, or pets need to be viewed in light of their own cognitive limitations.
Despite and because of these cognitive limitations, the age span between one and two represents a watershed period in the development of aggressive-like behavior. For infants less than a year, physical immobility limits the frequency of aggressive-like behavior. Although children less than 8 months old are clearly capable of using physical force to obtain an object (see Piaget, 1952), their accessibility is constrained by their inability to walk and in most cases, crawl. With the onset of walking at 12 months and gradual increase in coordination during the second year, the accessibility issue becomes moot. The increase in physical mobility is of great concern to parents, as the infant now has the capacity to explore unchartered territory without the requisite knowledge base. In some ways, it is comparable to parent's predicament in handling the behavior of adolescents. In both instances, the child has the necessary "equipment" to engage in behavior that may cause harm to self or others without sufficient decision-making skills.
Two examples discussed by Maccoby (1980) capture the developmental transition children and parents undergo between age one and two. The first is from a study of one-two year-olds by Bronson (1975), who observed groups of three-four children in a free play activity. Both one and two year-olds showed a comparable number of disagreements over toys; however, children's emotional intensity surrounding reactions to conflicts increased with age. Two year-olds were more distressed and angry when a toy was taken from them. The loss of the toy affected the quality of the child's play after the incident, but also appeared to offend the child's very sense of self. This study points out how the child comes to understand the term "mine." As Maccoby writes, "... between the ages of one and two years, is an increase in the intensity of involvement with objects, a staking out of claims, and an increasingly intense emotional reaction to encounters over possession" ( p. 119). As Goodenough (1931) documented over 50 years ago, angry outbursts peak in the middle of the second year for both boys and girls. Tremblay (1998) has recently corroborated these findings with respect to aggressive behavior, reporting that by 17 months of age, 70% of children take toys away from other children, 46% push others to obtain what they want, and 21-27% engage in one or more of the following behaviors with peers: biting, kicking, fighting, or physically attacking. Tremblay also reports that aggression occurs more frequently for infants with siblings, especially for girls (e.g., hitting, kicking, biting), providing daily opportunities for conflicts over possessions.
A second example points to the challenge parents must face in responding to a more physically mobile and potentially destructive child beginning in the second year. Ausubel (1958) characterizes the process by which parents set rules as an ego devaluation crisis for infants. This type of parenting differs markedly from the first year, when most parents serve the infant's wishes unconditionally. In the second year, parents are also more likely to interpret the infant's misbehavior as more intentional, and as such, meriting discipline. Ego devaluation is the shock an infant must contend with in responding to a formerly servant-like parent. Children begin to realize that parents are satisfying their needs because the parents want to, not because they have to. The implication is that children come to accept their role in the family as relatively powerless beings who ultimately must yield to parental authority. Thus, it is not surprising that the 2nd and 3rd years are marked by increasing negativity on the part of the infant as s/he tests the limits of adult authority in response to parents' attempts to expedite socialization. Of course, the infant's day of reckoning is not a foregone conclusion. It is quite possible that in cases in which children develop early conduct problems, a very different lesson is learned; namely, if I persist long and hard enough, I can continue to get my way. Empirical support for such a coercive process is discussed later in the chapter.
THE STABILITY OF EARLY AGGRESSION
Children's limited ability to understand the impact of their aggressive behavior, coupled with the developmental transitions taking place during the 2nd and 3rd years, make it important to examine its stability. As children are trained to desist from using aggressive conflict resolution strategies, rates of aggressive behavior gradually decrease from age two to five. The decrease in aggression is supported by data from our longitudinal study of 300 low-income boys. Using the same five items of aggressive behavior common to the age 2-3 and 4-16 versions of the Achenbach CBCL, maternal reports of boy's aggressive behavior (means) decrease from 2.6, 2.5, 1.6, and 1.3 at 24, 42, 60, and 72 months, respectively. Statistically significant differences in rates of aggression were found between 24 and 42 months and 60 and 72 months (for all four comparisons, p-values < .001).
Unfortunately, there are relatively few studies of the stability of aggressive and other types of disruptive behavior beginning in infancy. Studies of slightly older children suggest that continuity is moderate from the preschool to school-age period. In one of the first studies of the latter type, Jersild and Markey (1935) found that among 2-4 year-olds, peer aggression showed a stability of .7 over a 9-month period. More recently, Richman et al. (1982) identified the top 14% of 3-year-olds from a parental questionnaire of behavior problems, and followed them in comparison to a control group of children from similar backgrounds. Problems persisted in 63% of these children at age 4 compared to 11% of the control group, and 62% at age 8 compared to 22% of the controls. Similarly, Campbell and colleagues have followed two cohorts of hard-to-manage children from preschool through school-age (Campbell, 1990). In the first cohort, children identified at age 3 showed moderate continuity of behavior problems at ages 6, 9, and 13. Fifty and 48% of those with problems at age 3 showed clinically-significant problems at ages 6 and 9, respectively. Campbell (1994) followed a second cohort of overactive and inattentive boys and found comparable rates of continuity from preschool to school-age.
The few longitudinal studies initiated prior to age 3 largely corroborate these results. Rose and colleagues (1989) found a correlation of .73 on the Achenbach Externalizing factor between the ages two and five. In a study specifically focused on aggressive behavior conducted by Cummings and colleagues (1989), the stability of physical aggression from age two to five was as high as r = .76 for males among a sample of 43 subjects (22 boys). This study is notable because it is one of the few in which observational data were obtained at both assessment points to evaluate aggression, and because the stability was obtained while having children interact with same-age peers. In our own work which relied on both observational measures and parental report, Keenan and Shaw (1994) found correlations ranging from .23 to .45 between 1.5 and 2 years for object- and person-related aggressions among 89 toddlers. For boys only, observed aggression was also related to maternal report of CBCL Externalizing at age 3, r = .34) (Shaw et al., 1994) and symptoms of DSM disruptive behavior disorders at age 5 using the K-SADS, r = .30) (Keenan et al., in press).
Finally, in analyzing data from our more recent cohort of low-income boys, we found among boys identified at or above the 90th percentile on the CBCL Externalizing factor at age 2, 63% remained above the 90th percentile at age 5, and 97% remained above the median. At age 6, 62% remained in the clinical range and 100% (all 18) remained above the median. False negative rates are relatively low for the same factors. Only 13 and 16% of boys below the 50th percentile on Externalizing at age two moved into the clinical range at ages five and six, respectively. When clinically-elevated groups were formed at age two based solely on CBCL items involving aggressive behavior, and the outcome variable was the narrow-band CBCL Aggression factor (comprised of aggressive, destructive, and oppositional symptoms) at age 5, prediction to clinical outcome was further improved. Approximately 88% of boys identified as aggressive at age two continued to show clinically-elevated symptomatology at age 5 (false negative rate 22%). At age six, 58% remained in the clinical range on Aggression and 92% remained above the median (false negative rate 27%). These data are comparable to those reported by Patterson (1982) concerning the stability of antisocial behavior from school-age to late adolescence. Of those identified in the top 5%, Patterson found 38.5% stayed at or above the 95th percentile and 100% stayed above the sample mean ten years later. Similar to Patterson's data with older children, the stability findings of early childhood also suggest that there are relatively few "late-starters" who begin to show clinically-elevated rates of disruptive behavior after infancy.
Taken together, the results suggest that aggression shows moderate to strong continuity beginning in early childhood. The data from our own sample indicate comparable stability of clinically-elevated scores as reported for older children. That 63-88% of those identified with clinically-elevated scores at age two continued to maintain clinical status three-four years later is a strong endorsement of the need for early intervention programs. It should be noted that these stability levels may be limited to other high-risk samples. Still, the results suggest that aggressive behavior is relatively stable for the most aggressive children during a period of great developmental transition. Finally, as Rutter (1997) notes, despite the high stability of aggressive behavior problems from infancy, it remains to be established whether these very early starters will go on to demonstrate severe antisocial behavior during school-age and adolescence.
CORRELATES OF AGGRESSION DURING INFANCY
Several factors have been theorized to influence the course of aggression in young children. Unfortunately, relatively few studies have been undertaken to validate these hypotheses with infants. Below we review areas that have been postulated to affect early disruptive behavior and research studies that have addressed these issues. The domains include infant temperament, parental attributes and support, parenting, and cumulative family adversity.
Several investigators have examined the relation between early temperamental attributes and conduct problems. Most studies have focused on infant negative emotionality (Bates et al., 1985), although recent research has begun to explore individual differences in attention-seeking behavior and the expression of anger (Rothbart et al., 1994; Shaw et al., 1994). Negative emotionality is thought to be directly related to later oppositional and aggressive behavior, and indirectly through its effects on parenting (Bates, 1985). Studies examining the former pathway have shown modest to moderate predictive validity (Maziade et al., 1989; Sanson et al., 1991). However, interpretation of these findings must be tempered by the use of maternal report to assess infant difficulty and later behavior problems. In the few studies using multiple informants, relations between maternal report of infant difficulty and later externalizing problems have been modest or nonsignificant (Bates et al., 1985; Belsky et al., 1998). This indicates that the direct association between infant temperament and later externalizing problems may be at least partially due to the parent's stable perception of the child rather than the child's behavior. However, such a bias may still have a significant, albeit indirect, effect on child antisocial outcome. Mothers who perceive their infants as high on negative emotionality may be less responsive to their requests for attention and use more harsh discipline strategies in response to their behavior.
In our own work, we have sought to understand the relation between infant attention-seeking, maternal unresponsiveness, and early conduct problems using an interactive measure of attention seeking. Employing an observational measure developed by Martin (1981), infants are placed in a high-chair with nothing to do, while mothers are instructed to complete a questionnaire and attend to the infant's needs. Persistent attention-seeking is assessed by coding infant bids for behavior following initial bids that are unresponded to by the caregiver. Viewed from an interactional context, persistent attention-seeking is likely to be aversive to the caregiver who is initially unresponsive to the infant. Thus, attention-seeking may be a direct precursor of disruptive problems, but also indirectly lead to disruptive behavior by influencing caregiver's perception and parenting of the child. Attention-seeking assessed observationally between 10 and 12 months has been directly related to conduct problems in between the ages of 2 and 3.5 in three studies, including observed and maternal report of aggression at age two (Martin, 1981; Shaw et al., 1994, 1998a).
A related interest has grown in exploring individual differences in infant's expression of anger, stemming from work on the affective bases of aggression. It has been hypothesized that infants who respond to goal frustration with intense and prolonged anger may be at elevated risk for aggressive behavior problems (Calkins, 1994; Cole et al., 1994).
Longitudinal studies from infancy to early childhood provide preliminary support for this premise. Zahn-Waxler and colleagues (1990) examined relations between aggression at age two and subsequent behavior problems in the offspring of well and depressed mothers. Both normative (object struggles, rough play) and dysregulated (hostility toward adults, out-of-control behavior) forms of infant aggression were identified. Only dysregulated aggression predicted externalizing problems reported by mothers at age 5 and children's reports of problem behavior at age 6. Similarly, Kuczynski and Kochanska (1990) identified several noncompliance strategies used by two year-olds, including passive noncompliance, simple refusal, direct defiance, and negotiation. Of these subtypes, only direct defiance, that is, noncompliance accompanied by poorly controlled anger, predicted externalizing problems at age 5. These studies indicate that the long-term consequences of aggressive, noncompliant behavior may depend on concomitant patterns of emotion regulation.
Parental Attributes and Support
Parental characteristics and support have been hypothesized to influence infant aggressivity in multiple ways. At an environmental level, parental maladjustment and low social support may compromise parenting. Parents who are impaired by psychopathology are also more likely to model maladaptive problem-resolution strategies for children to observe, including higher rates of interparental conflict and the use of physical force to resolve disagreements. From a genetic perspective, maladaptive characteristics may be passed on to children, including such traits as impulsivity and low frustration tolerance (Raine, 1997). Among older children, conduct disorder and delinquency are associated with antisocial personality characteristics in both mothers and fathers (Robins et al., 1975). This relationship has since been corroborated in three samples of infants. Keenan and Shaw (1994) found that familial criminality was related to boys' aggression at age 2, after controlling for aggression at 18 months and maternal age - a result we have replicated in a our larger cohort of low-income boys (Shaw et al., 1998b). In a large sample of 17-month olds, Tremblay (1998) also found father's report of antisocial behavior before the birth of the child to be related to infant aggression. The relations between criminality and infant aggression tend to be modest (r's range from .15 to .25) but statistically significant.
Parental mood disorders have also been examined as risk factors for early conduct problems. However, the majority of these studies have ascertained child disruptive behavior during preschool age or thereafter. When young children with disruptive behavior problems are compared to normal controls, mothers of children with externalizing problems report more depressive symptomatology (Mash & Johnston, 1983), and these differences persist at follow-up (Campbell, 1994; Webster-Stratton, 1990). In our own work, depressive symptoms at 18, 24, and 42 months have been related to both concurrent and subsequent conduct problem from 18 to 72 months of age according to both parent and teacher report (Owens, 1998).
In addition to examining parental personality and adjustment, investigators have identified sources of stress and support within and outside the family system that are related to the occurrence of child behavior problems. Again, the majority of these studies begin at preschool age. Among preschoolers and school-age children, marital conflict has been found to be associated consistently with externalizing problems, particularly when conflicts involve disagreements over childrearing practices (Dadds & Powell, 1991; Jouriles et al., 1989). This finding has been corroborated repeatedly with infants (Gable et al., 1992; Shaw et al.,1998b) beginning with assessments of marital satisfaction/conflict at ages 1-2. In addition, quality of maternal social support outside the family has been positively related to responsive parenting, and negatively related to maternal depressive symptoms and child disruptive behavior in the first two years (Burchinal et al., 1996; Shaw et al., 1998b).
During infancy, maternal responsiveness has been the focus of research on parenting factors associated with externalizing behavior problems. According to attachment theory, contingent responsiveness is critical to the development of self-regulation skills, the resultant bond between parent and infant, and later patterns of the child's behavior (Bowlby, 1969; Sroufe, 1983). An infant who receives less contingent caregiving may engage in disruptive behavior to obtain parental attention (Greenberg & Speltz, 1988), and also have less at stake to lose by being noncompliant and aggressive (i.e., loss of love) (Shaw & Bell, 1993). Thus, maternal unresponsiveness could trigger the initiation of coercive interaction patterns and the development of more serious conduct problems at school-age.
Research examining infant attachment security and direct observations of maternal responsiveness during infancy have found support for their relation with later externalizing problems (Erickson et al., 1985; Renken et al., 1989). Regarding infant attachment security, a consistent association has emerged between the insecure disorganized (type "D") category and later externalizing problems, particularly problems of aggression for boys (Lyons-Ruth et al., 1996; Shaw et al., 1996). The D category is yet to be associated with constitutional or genetic attributes (e.g., negative emotionality), but has been related to specific behavioral and psychological problems in caregivers. These include the caregiver's own maltreatment, unresolved loss or trauma, depression, and interparental conflict, all of which may impair the quality of parenting (van Ijzendoorn et al., in press). A recent meta-analysis found a combined effect size of r = .29 in 12 studies (total n = 734) examining the relation between disorganized attachment status and conduct problems. It should be noted that the meta-analysis included studies of attachment security that occurred at preschool-age; however, effect sizes are similar across age periods (van Ijzendoorn et al., in press).
Direct observations of maternal responsiveness have also been related to concurrent and later externalizing problems, particularly for boys (Gardner, 1987). Using the same high-chair task described above, three studies have found low maternal responsiveness between 10-12 months to be associated with boys' disruptive behavior at ages 2-3.5 (Martin, 1981; Shaw et al., 1994, 1998a). In all three studies, the interaction of low maternal responsiveness and infant attention-seeking behavior added unique variance to the prediction of later disruptive behavior above and beyond the individual parent and child factors.
As it follows from developmental theory that maternal responsiveness should be studied as a correlate of early disruptive behavior in the first year, discipline practices should play a more salient role in the development of disruptive behavior in the second and third years. While maintaining a positive relationship, parents also begin exerting their will to protect the infant and other family members' physical well-being. In addition, parents begin to expect greater self-regulatory control in so the child can perform developmentally appropriate tasks that require greater social and cognitive competence. Parents, in fact, do report the second year to be a time of increased stress, during which patience and coping mechanisms are tested (Fagot & Kavanaugh, 1993). From a social learning perspective, rejecting parents might unintentionally reinforce children's disruptive behavior by attending only to negative behavior. The child may learn that the most successful way to terminate a parent's noncontingent rejecting behavior is to act in a highly aversive manner. The parent, in response, may withdraw from the confrontation, thereby increasing the likelihood of future coercive interaction (Patterson, 1982). In addition, rejected children may fail to internalize moral values pertaining to concern for the rights and well-being of others (Shaw et al., 1998a). Parental warmth has been considered an important component of children's willingness to accept messages from parents regarding moral behavior (Grusec & Goodnow, 1994). Yet there is a dearth of studies on the effects of parental rejection on child behavior prior to preschool-age despite consistent associations between rejection and antisocial behavior among older children (Loeber & Stouthamer-Loeber, 1986). We recently found observed parental rejection at age two to be moderately related to parental report of externalizing problems at age 3.5 (Shaw et al., 1998a). Interestingly, maternal rejection added unique variance after accounting for concurrent child problem behavior and earlier maternal unresponsiveness. Maternal rejection was also one of the few predictors of conduct problems for both boys and girls.
Chronic Family Adversity
A number of investigators have noted that the accumulation of risk factors is related to several types of child problem behavior, including disruptive behavior problems (Sameroff et al., 1987; Zeanah et al., 1997). Rutter and colleagues (1975) were perhaps the first to suggest that the presence of multiple familial stressors may be a better predictor of child behavior problems than any specific factor alone. Consistent with this hypothesis, several investigators have found that the likelihood of behavior problems increases with the number of stressors present (Sameroff et al., 1987). In the past decade this hypothesis has been corroborated with infants (Sanson et al., 1991; Shaw et al., 1998b). In two studies of chronic family adversity assessed when infants were between one-two years of age, consistent relations were found with later disruptive behavior problems between ages 2 to 3.5. Relations were more robust for externalizing verus internalizing problems. In addition, when groups were dichotomized based on clinical symptomatology, families with stressors present from 4 different domains had a 15 times greater probability of having clinically-elevated scores than those with 0 stressors present. Stressor domains included maternal adjustment, family climate, parental aggressivity, and sociodemographic risk. The findings on chronic family adversity raise issues about the need to intervene with families at levels beyond the door of the therapist's office. It is also a reason the stability data are likely to be "inflated" in samples from impoverished backgrounds because of the number and type of stressors facing such families. Preventionists and interventionists need to consider these nonpsychological factors that affect parenting ability, including social support within and outside the family, overcrowding in the home, neighborhood dangerousness, and family income.
While knowledge of the course and correlates of infant aggression is growing, psychosocial interventions that target this problem have yet to be evaluated empirically. In the absence of such data, the treatment recommendations provided here are guided by two principles that emerge from the preceding review.
First, early aggressive behavior must be considered within the interpersonal context in which it occurs. The research discussed above suggests that infant aggression originates in and is maintained by multiple, interacting factors in the caregiving milieu, including characteristics of the infant and his or her parents, as well as environmental pressures that impinge on the parent-infant relationship. We assume that the reduction of infant aggression requires identifying and addressing major etiological influences that are co-operating in a particular case. Hence, the focus of treatment must be broadened beyond the infant to include factors such as the emotional quality of parent-infant interactions, the ways in which parents respond to their infant's misbehavior, and stressors that impair parents' ability to provide adequate care.
Second, aggression should be viewed from a developmental perspective. A developmental framework dictates that clinicians approach aggressive behavior in light of the salient issues of a given age period (Sroufe & Rutter, 1984). For example, the establishment of an effective attachment relationship is a central goal of the first year of life. Aggressive behavior may be a result of an attachment relationship that is characterized by anger and frustration (Boris chapter, this volume). Similarly, the development of autonomy is a primary task in year two, while the establishment of flexible self-regulation is a critical issue in the third year and beyond. Aggression may occur when factors within the child or family prevent the realization of these age-specific goals. It is critical that the timing and content of treatment be attuned to the developmental status of the child.
This section describes clinical approaches to aggression in the first three years of life. In keeping with relevant research findings and theoretical models, the strategies presented here are oriented toward relational and developmental processes that are thought to contribute to aggressive behavior in infancy. Each approach is covered in greater detail elsewhere, but usually in reference to other problems or to older children. Our goal is to illustrate how these interventions may be applied to infant aggression in an integrated fashion.
According to attachment theory, the emotional bond formed between an infant and his or her parents has far-reaching consequences for adjustment (Bowlby, 1969). Parental responsiveness is thought to be a primary determinant of the quality of the attachment relationship and, therefore, the behavioral tendencies of the developing child. Infants with unresponsive parents may resort to aggression to gain attention and are less likely to fear losing their parents' love by acting out. As an initial intervention, the clinician must attempt to optimize parental responsiveness to an infant who may already pose considerable challenges to even the most patient caregiver.
Several approaches have been developed to modify the ways in which parents relate to their infant. Infant-parent psychotherapy (Lieberman et al., this volume) is based on the psychoanalytic hypothesis that parents reenact with their children unresolved conflicts from important relationships in their own childhood. For instance, conflicts of parents with an aggressive infant may involve themes of aggression (e.g., abuse or domestic violence), resulting in feelings of anger or rejection toward their child. From this perspective, behavioral disturbance is co-determined by the mother's projections and the infant's reactions to them (Robert-Tissot et al., 1996). Treatment involves helping parents to understand the relationship between childhood experiences and current behavior as caregivers. Additionally, the unconditional support of the therapeutic relationship affords a corrective attachment experience for the parent. These changes permit parents to respond more effectively to the needs and emotions of their infant.
Interaction guidance (McDonough et al., this volume) also focuses on parents' perceptions of and responses to their infants; however, the emphasis is on observed interactional sequences rather than unconscious representations arising from past experience. The clinician assists parents in interpreting accurately the infant's signals (e.g., differentiating between anger and distress) and determining appropriate reactions to these cues. By providing an environment that is optimal for the formation of secure attachment, the parents and clinician maximize the child's ability to form a harmonious, reciprocal emotional bond, not only with the parent but with siblings, peers, and other adults.
Approaches that target parental responsiveness provide a cornerstone for the treatment of aggression in the first year. However, the clinician should remain sensitive to attachment issues beyond the first birthday and may choose to implement the foregoing strategies in combination with treatments that are appropriate for older infants. The work of Greenberg and Speltz (1988) illustrates how learning theory and attachment conceptualizations may be integrated in the treatment of early conduct problems.
Discipline practices become increasingly important in shaping infants' behavior in the second and third years. Support is accumulating for a hypothesis that states that the manner in which parents impose and enforce limits has important implications for the development of aggression (Patterson, 1982; Webster-Stratton & Herbert, 1994). Parent management training seeks to change discipline practices that may inadvertently foster and maintain young children's use of aggression (Webster-Stratton & Herbert, 1994). Because treatment targets specific patterns of reinforcement that occur within a family, it is important to make a detailed assessment of parent-child interactions, preferably in the home environment. A central focus in parent management training is helping caregivers to avoid the development of coercive interactions, wherein parent and child each employ increasingly aversive behaviors in an attempt to control the outcome of discipline encounters. In service of this goal, parents learn to observe their infant's behavior in an objective, unemotional manner and to implement appropriate consequences in response to aggression.
Time Out is a useful discipline technique because it curtails negative parent-child interchanges while ensuring that aggressive behavior goes unrewarded. Time Out may be used with infants as young as 18 months and can be implemented in the same fashion as with older children, but for shorter durations (a minute per year of the child). Parents should warn infants in advance about the unacceptability and consequences of aggressive behavior. When aggression occurs, the infant is removed immediately to an area where alternative stimulation is not available. Time Out should be used judiciously. Less extreme misbehavior may desist in the absence of parental attention. The clinician can discuss with parents which behaviors merit Time Out and which may be ignored and should emphasize the importance of applying these criteria consistently. Finally, parents should learn to identify behaviors that indicate that the infant may soon become aggressive (e.g., physical signs of anger or frustration) and events that serve as triggers. It may be possible to intervene before aggression occurs.
Just as parent management training shows caregivers how to make aggressive behavior less worthwhile for their infant, parents also learn to increase the frequency of prosocial behavior through the use of positive reinforcement (Webster-Stratton & Herbert, 1994). The clinician can aid parents in identifying and monitoring desired behaviors, choosing appropriate reinforcers (e.g., praise, treats), and providing rewards in a consistent fashion. Social modeling affords a second method for increasing prosocial behavior. Parents and siblings should be encouraged to use appropriate problem-solving strategies in dealing with one another.
The clinician may find that parents are unable to comply with treatment recommendations. If this occurs, it is possible that the family's social resources are too overwhelmed by the challenges of daily life to permit significant change. For instance, there may be too many family members and too little privacy for parents to provide one-on-one attention for the infant. A parent's depression may prevent him or her from instituting time out procedures in a consistent manner.
Or the neighborhood may be so dangerous that parents are unwilling to become less restrictive with their children. Factors that may interfere with treatment should be examined carefully during the assessment period. Home visits are particularly useful in making an accurate evaluation family adversity and offer the clinician a chance to observe the circumstances in which aggression occurs.
Multisystemic therapy (MST), a treatment approach developed by Henggeler and Bourdin (1990), provides a useful framework for addressing contextual processes that adversely affect parent and child functioning. Originally used with conduct disordered adolescents, efforts are underway to use MST with infants and their families (Pickrell, 199?). Rather than applying a single therapeutic technique, MST draws from a variety of treatment modalities. For example, a multisystemic treatment plan may include family-based interventions (e.g., structural family therapy) to increase family cohesion and decrease hostility, as well as more concrete assistance with problems of living, such as helping the family find adequate housing, in addition to the parent-infant approaches described above.
Depending on the type and severity of challenges the family faces, the clinician can provide needed services and/or put the family in contact with appropriate agencies. The clinician should evaluate the effects of the services on parental functioning throughout the course of treatment and introduce appropriate adjustments as needed.
Interventions Outside Therapy
Infants in their second or third year may be aggressive in a variety of settings, such as day care or play groups. Individuals in contact with an aggressive infant in these contexts can augment the efforts of the clinician and the child's family by becoming active participants in the ongoing treatment of aggression. The clinician should consult with and instruct these individuals on how to develop and maintain appropriate interventions to reduce the infant's aggressive behavior. The clinician can also provide those involved with the support to continue during difficult times.
As noted in the section on parent management training, the young child may have learned to use aggression to gain control over the environment. Thus, one way adults in the infant's life can help to reduce aggressive behavior is by being consistent in when and how they afford the control the infant seeks. Praise and rewards should be given for periods in which no aggression occurs. Equally important are others' responses to aggression by the infant. Adults should carefully avoid giving in to demands accompanied by aggression or threats of force and should be prepared to respond to aggressive behavior using consequences agreed upon in advance by members of the treatment group. The clinician and members of the treatment network should review periodically the consequences of both prosocial and aggressive behavior so that they are understood by all parties and can be modified according to the infant's progress.
The following example is based on a composite of several clinical cases. It is presented to illustrate the challenges inherent in meeting the needs of aggressive infants and their families.
Mrs. Amy Williams called the mental health clinic complaining about the destructive behavior of her two year-old son, Tommy. Mr. and Mrs. Williams lived in a two-bedroom apartment with their three children: Melissa age 6, Tommy, and Joan, 7 months old. Mrs. Williams sounded very worried over the phone about Tommy's interactions with herself, Melissa, and Joan. She reported that Tommy had always been a child who became angry easily and took out his frustrations on others physically. This had not been a problem until the past year when he became more physically mobile. Tommy's aggressive behavior reportedly increased following the arrival of Joan, which resulted in less attention from both parents. In the past few months, Tommy had broken several family valuables, toys, and scratched the dining room table and wood floor. On several occasions he had been found pulling forcefully on Joan's legs and arms. Mrs. Williams no longer felt safe leaving Tommy with Joan in the same room unattended. In addition, Tommy responded to his parents' requests to stop destructive or noncompliant behavior with verbal obstinance and physical force. Mrs. Williams reported that her "patience had been growing thin" with Tommy, and believed it had adversely affected her caregiving with the other children and the quality of her marriage. According to Mrs. Williams, Mr. Williams had been helpful when he was home, but often arrived from work after dinner around the children's bedtime. When asked about other sources of support, Mrs. Williams' stated that she "used to" have two or three close friends, but had had relatively little contact with them since the births of Tommy and Joan. Mr. Williams' parents lived in the area, but Mrs. Williams expressed reluctance about using them for emotional support or childcare. Mrs. Williams worked part-time until the arrival of Tommy. Since then, she had been a full-time mother.
An intake session was arranged to gain a better sense of Tommy's problematic behavior, the quality of relationships Tommy had with family members, and the family's coping resources. Mr. Williams was able to attend an early evening session, but expressed concern about being able to attend meetings on a regular basis. With encouragement from the therapist, Mrs. Williams was able to recruit Mr. Williams' mother to babysit Joan during the visit. Note that even setting up the initial appointment had tested the family's coping resources (e.g., flexibility from Mr. Williams' employer and making use of extended family for childcare).
During the initial part of the interview, Tommy and Melissa were allowed to play with a set of toys in the same room to observe Tommy's behavior with his elder sibling. In addition to evaluating the quality of the sibling relationship, the free-play procedure provided an opportunity to observe how the parents responded to the children's conflict, should it arise. Based on Mrs. Williams' report, the therapist was confident that Tommy would act aggressively towards Melissa during the session. After 10 minutes, during which time the children had become involved in pretend play with action figures, Tommy became upset about a statement made by Melissa acting as "Batgirl." In response, Tommy forcefully removed Batgirl from Melissa's hand, threw the toy against the wall, and hit Melissa on the arm. Both parents simultaneously looked at each other, then at the therapist for assistance, following which Mr. Williams forcefully picked up Tommy while yelling and moved him to the couch beside his parents. Tommy responded by calling Mr. Williams several unflattering names, and only allowed his father to pick him up after continued physical and verbal resistance. After a few minutes, Tommy was allowed to return to play with the action figures. However, after this sequence of events repeated itself two more times during the next 20 minutes, he was instructed to play in a different part of the room than his sister.
When not dealing with Tommy's disruptive behavior, the parents discussed their troubles in dealing with Tommy. A pattern was described in which Tommy "got inside" each parent emotionally, eliciting a punitive response. Mr. Williams confirmed having felt this way earlier in the session. The pattern was similar to Patterson's (1982) coercive cycle, in which parents and child reinforced the aversive behavior of the other, leading to an escalation of the problem behavior.
The therapist also examined the history of Tommy's attachment to the parents, particularly prior to the arrival of Joan. In comparison to Melissa, Mrs. Williams described Tommy as more difficult to "connect with" as a young infant, a pattern which persisted during his first year. Since he was approximately 15 months old, she had found herself spending most of her time reprimanding Tommy for dangerous or aggressive behavior. Mrs. Williams stated that she still had positive interactions with Tommy, but these had become more fleeting in the past six months. She also reported feeling guilty about not being able to provide Tommy with enough attention since the arrival of Joan. Mr. Williams also expressed remorse about his inability to assist more with childcare, but felt no other choice given his job demands. When the therapist inquired about working different hours or slightly shorter days, he expressed doubts about his employer's willingness to reduce his hours, and concern about the possible financial consequences for the family. However, he said he would consider the option given the situation. The Williams also agreed that dealing with Tommy had affected their own relationship adversely, particularly their ability to support one another.
The Williams family faced several issues typical of infants with aggressive behavior problems. These included an aggressive child who had previously shown a tendency to become angry easily, parenting discipline strategies that had unintentionally exacerbated the child's aggressive behavior and further compromised the quality of the relationship between parents and child, a marital relationship that was "on edge," and limited use of support from friends and relatives. In addition, the family was facing a normative developmental transition with the arrival of Joan. Older siblings often regressed to behavior typical of younger children in response to the depletion of parental attention necessitated by the newborn's birth.
A multifaceted treatment package was designed which incorporated elements from several modalities. Treatment included components from Webster-Stratton's and Patterson's Parent-Training approaches, Lieberman's infant-parent psychotherapy (1993), and Minuchin's (1974) structural family therapy. Before the therapist sought to implement change, a concerted effort was made to place the family's issues in a normative developmental context. Without minimizing the seriousness of Tommy's problems and the parents' distress, the family was informed of how typical behavior problem issues were for older siblings of newborns. Then, before addressing discipline techniques, an effort was made to improve the quality of the relationship between Tommy and his parents. Patterson (personal communication, January 15, 1993) has suggested that by encouraging parents to be more warm and reinforcing, it increases their "bank account" with the child. There are various reasons for parents to resist being warm with their infants. In some instances, parents may be inexperienced in reading and/or responding effectively to infant cues. In cases like the present one in which the child has come to be seen as unmanageable, parents may become "blocked" from interacting in a warm manner because of "battle scars" from their experience with the child. Thus, it was necessary for the therapist to play an active role in modeling warm and responsive behavior to show the parents that Tommy was still capable of reciprocating in a positive manner. Once over their initial hesitation, both parents approached Tommy in a friendly, engaging manner. The second session was facilitated by having Mr. Williams' mother watch both Melissa and Joan, providing an hour of undivided attention for Tommy with his parents.
Discipline issues also were addressed in the latter half of the second session. Following guidelines recommended by Webster-Stratton (1994), the parents were instructed to intervene with Tommy in a more objective, unemotional manner, and to use discipline techniques that decreased the emotional valence of their interactions. Consistency and firmness were emphasized, but given the Williams' admitted reactivity to Tommy, significance was placed on the emotional tenor of their delivery; the parents must simultaneously demonstrate that aggressive behavior would not be tolerated nor modeled in administering punishment. At the end of the session, Tommy was recruited to help the parents in practicing a 2-minute time out procedure, agreeing to engage in a pretend fight with the therapist to elicit a calm parental response. The therapist and parents also brainstormed about behaviors Tommy displayed when he was about to act aggressively so they might intervene prior to more explosive outbursts.
Both relational and discipline issues were revisited each week. At the same time, the therapist explored how intra- and extra-familial resources could be better used. These included interventions designed to improve the quality of relations between Mr. and Mrs. Williams, provide childcare assistance for Mrs. Williams, and use extra-familial sources of support for both Mrs. and Mr. Williams. To improve the Williams' relationship, couple sessions were held every fourth week to discuss parenting and marital issues. Mr. William's mother continued to provide childcare during therapy sessions and also during weekend evenings so the Williams could spend time alone. Mr. Williams arranged his schedule to make three out of four monthly sessions. Mr. Williams' mother also attended two sessions to improve consistency in the administration of discipline practices. After initial resistance, the elder Mrs. Williams agreed to use time outs with Tommy when she cared for him in her son's house (but not necessarily in her own house). Mr. Williams also negotiated more family-friendly work hours at a slight financial cost to the family. As a result, Mr. Williams arrived home at 5:00 PM two days a week, prior to the witching hours of parental care before bedtime. Finally, both Mr. and Mrs. Williams were encouraged to spend time with adult friends individually on occasion (once every three weeks) to provide external support.
Treatment progressed in a two-steps-forward-one-step-back manner. After responding initially to the increased positive attention and more consistent and less emotionally-laden discipline, Tommy's behavior improved. However, after two weeks, Tommy's behavior deteriorated. The parents were encouraged to stay with the regimen, particularly continuing to approach Tommy proactively in a warm manner and maintaining a calm demeanor when administering discipline. During subsequent weeks, Tommy's behavior showed gradual improvement with fewer and less extreme bouts of aggressive behavior. After 14 weeks of therapy, his behavior had improved sufficiently to reduce meetings to monthly checkups. Treatment was successfully concluded 6 months after the initial intake.
Summary This chapter has described the current state of knowledge on aggressive behavior problems during infancy. Despite cognitive limitations in fully understanding aggression and the high frequency of the behavior, aggression during infancy shows comparable stability and similar correlates to aggressive behavior at older age periods during childhood. The implications of these findings are that prevention and intervention efforts need to be directed at similar targets as they are for older children, with special attention to parent-child relationships. Given infant's greater dependence on relationships in the home, approaches that reinforce responsive caregiving and consistent, even-tempered discipline practices, and that address factors that affect parental functioning, appear the most logical. A case example was provided to illustrate how successful intervention might be implemented. It is recommended that an ecologically-based treatment package be employed to deal with the multiple challenges facing families with aggressive infants.
Ausubel, D.P. Theory and problems of child development. New York: Grune & Stratton.
Bandura, A. (1979). Psychological mechanisms of aggression. In M. von Cranach, K. Foppa, W. Lepenies, & D. Ploog (Eds.), Human ethology: Claims and limits of a new discipline (pp. 316-356). Cambridge: Cambridge University Press.
Bates, J.E., Maslin, C.A., & Frankel, K.A. (1985). Attachment security, mother-child interaction, and temperament as predictors of behavior-problem ratings at age three years. In I. Bretherton & E. Waters (Eds.), Monographs of the Society for Research in Child Development, 50, Nos. 1-2, 167-193.
Belsky, J. Hsieh, K., & Crnic, K. (1998). Mothering, fathering, and infant negativity as antecedents of boys' externalizing problems and inhibition at age 3 years: Differential susceptibility to rearing experience? Development and Psychopathology, 10, 301-320.
Bronson, W.C. (1975). Developments in behavior with age mates during the second year of life. In M. Lewis & L.A. Rosenblum (Eds.), The origins of behavior: Friendship and peer relations. New York: Wiley.
Bowlby, J. (1969). Attachment and loss, Vol. 1. New York: Basic Books.
Burchinal, M.R., Follmer, A., & Bryant, D.M. (1996). The relations of maternal support and family structure with maternal responsiveness and child outcomes among African American families. Developmental Psychology, 32, 1073-1083.
Buss, A.H. (1961). The psychology of aggression. New York: Wiley.
Calkins, S. (1994). Origins and outcomes of individual differences in emotion regulation. In N. A. Fox (Ed.), The development of emotion regulation: Biological and behavioral considerations. Monographs of the Society for Research in Child Development (pp. 53-72). Chicago: University of Chicago Press.
Campbell, S.B. (1990). Behavior problems in preschool children: Clinical and developmental issues. New York: Guilford Press.
Campbell, S.B. (1994). Hard-to-manage preschool boys: Externalizing behavior, social competence, and family context at two-year-follow-up. Journal of Abnormal Child Psychology, 22, 147-166.
Cole, P. M., Michel, M. K., & Teti, L. (1994). The development of emotional regulation and dysregulation. In N. A. Fox (Ed.), The development of emotion regulation: Biological and behavioral considerations. Monographs of the Society for Research in Child Development (pp. 73-100). Chicago: University of Chicago Press.
Cummings, E.M., Iannotti, R. J., & Zahn-Waxler, C., (1989). Aggression between peers in early childhood: Individual continuity and developmental change. Child Development, 72, 887-895.
Dadds, M.R., & Powell, M.B. (1991). The relationship of interparental conflict and global marital adjustment to aggression and immaturity in aggressive and nonclinic children. Journal of Abnormal Child Psychology, 19, 553-567.
Dollard, J., Doob, L.W., Miller, N.E., Mowrer, O.H., & Sears, R.R. (1939). Frustration and aggression. New Haven: Yale University Press.
Dunn, J., & Kendrick,, C. (1982). Siblings: Love, envy, and understanding. Cambridge, MA: Harvard University Press.
Erickson, M.F., Sroufe, L.A., & Egeland, B. (1985). The relationship between quality of attachment and behavior problems in preschool in a high-risk sample. In I. Bretherton & E. Waters (Eds.), Growing points of attachment theory and research. Monographs of the Society for Research in Child Development, 50, Nos. 1-2, 147-167.
Fagot, B., & Leve, L.D. (1998). Teacher ratings of externalizing behaivor at school entry for boys and girls: Similar early predictors and different correlates. Journal of Child Psychology and Psychiatry, 39, 555-566.
Fagot, B., & Kavanaugh, K. (1993). Parenting during the second year: Effects of children's age, sex, and attachment classification. Child Development, 64, 258-271.
Forehand, R., & McMahon, R J. (1981). Helping the noncompliant child: A clinician's guide to parent training. New York: Guilford.
Gable, S., Belsky, J., & Crnic, K. (1992). Marriage, parenting, and child development: Progress and prospects. Journal of Family Psychology, 5, 276-294.
Garber, J., & Dodge, K. (Eds). (1991). The development of emotion regulation and dysregulation. Cambridge: Cambridge University Press.
Gardner, F.E. (1987). Positive interaction between mothers and conduct-problem children: Is there training for harmony as well as fighting? Journal of Abnormal Child Psychology, 15, 283-293.
Goodenough, F.L. (1931). Anger in young children. Minneapolis: University of Minnesota Press.
Greenberg, M.T., & Speltz, M.L. (1988). Contributions of attachment theory to the understanding of conduct problems during the preschool years. J. Belsky & T. Negworski (Eds.), Clinical implications of attachment (pp. 177-218). Hillsdale, New Jersey: Earlbaum.
Grusec, J., & Goodnow, J. (1994). Impact of parental discipline methods on the child's internalization of values: A reconceptualization of current points of view. Developmental Psychology, 30, 4-19.
Grusec, J.E., & Lytton, H. (1988). Social development. New York: Springer-Verlag.
Henggeler, S.W., & Bourdin, C.M. (1990). Family therapy and beyond: A multisystemic approach to treating the behavior problems of children and adolescents. Pacific Grove, CA: Brooks/Cole.
Jersild, A.T., & Markey, F.V. (1935). Conflicts between preschool children. Child Development, 21, 170 - 181.
Jouriles, E., Murphy, C., & O'Leary, K. D. (1989). Interspousal aggression, marital discord, and child problems. Journal of Consulting and Clinical Psychology, 57, 453-455.
Kazdin, A.E. (1995). Conduct disorders in childhood and adolescence. Thousand Oaks, CA: Sage Publications.
Keenan, K., & Shaw, D.S. (1994). The development of aggression in toddlers: A study of low-income families. Journal of Abnormal Child Psychology, 22, 53-77.
Keenan, K., Shaw, D.S., Delliquadri, E., Giovannelli, J., & Walsh, B. (in press). Evidence for the continuity of early problem behaviors: Application of a developmental model. Journal of Abnormal Child Psychology.
Kuczynski, L., & Kochanska, G. (1990). Development of children's noncompliance strategies from toddlerhood to age 5. Developmental Psychology, 26(3), 398-408.
Loeber, R., & Stouthamer-Loeber, M. (1986). Family factors as correlates and predictors of juvenile conduct problems and delinquency. In M. Tonry & N. Morris (Eds.), Crime and justice: An annual review of research (Vol 7), Chicago: University of Chicago Press.
Lyons-Ruth, K. (1996). Attachment relationships among children with aggressive behavior problems: The role of disorganized early attachment patterns. Journal of Consulting and Clinical Psychology, 64, 572-585.
Maccoby, E.E. (1980). Social development. New York: Harcourt Brace.
Martin, J. (1981). A longitudinal study of the consequences of early mother-infant interaction: A microanalytic approach. Monographs of the Society for Research in Child Development, 46.
Mash, E., & Johnston, C. (1983). Parental perceptions of child behavior problems, parenting self-esteem, and mothers' reported stress in younger and older hyperactive and normal children. Journal of Consulting and Clinical Psychology, 51, 86-99.
Maziade, M., Cote, R., Bernier, H., Boutin, P., Thivierge, J. (1989). Significance of extreme temperament in infancy for clinical status in pre-school years. British Journal of Psychiatry, 154, 544-551.
Minuchin, S. (1974). Families and family therapy. Cambridge, MA: Harvard University Press
Patterson, G. (1982). Coercive family processes (Vol. 3). Eugene, OR: Castalia.
Piaget, J. (1952). The origins of intelligence in children. New York: International Universities Press.
Pickrell, S. (199?). to be completed
Raine, A. (1997). Antisocial behavior and psychophysiology: A Biosocial perspective and a prefrontal dysfunctio hypothesis. In D. Stoff, J. Breiling, & J.D. Maser, (Eds.), Handbook of antisocial behavior (pp. 289-304). New York: John Wiley & Sons.
Reid, J.B. (1993). Prevention of conduct disorder before and after school entry: Relating interventions to developmental findings. Special Issue: Toward a developmental perspective on conduct disorder. Development & Psychopathology. 5, 243-262.
Renken, B., Egeland, B., Marvinney, D., Mangelsdorf, S., & Sroufe, A. (1989). Early childhood antecedents of aggression and passive-withdrawal in early elementary school. Journal of Personality. 57, 257-281.
Richman, M., Stevenson, J., & Graham, P.J. (1982). Preschool to school: A behavioral study. London: Academic Press.
Robert-Tissot, C., Cramer, B., Stern, D. N., Serpa, S. A., Bachmann, J., Palacio-Espasa, F., Knauer, D., De Muralt, M., Berney, C., & Mendiguren, G. (1996). Outcome evaluation in brief mother-infant psychotherapies: Report on 75 cases. Infant Mental Health Journal, 17, 97-114.
Robins, L. N. & Rutter, M. (Eds.) (1990). Straight and devious pathways from childhood to adulthood. Cambridge: Cambridge University Press.
Robins, L., West, P., & Herjanic, B., (1975). Arrests and delinquency in two generations: A study of black urban families and their children. Journal of Child Psychology and Psychiatry, 16, 125-140.
Rose, S.L., Rose, S.A., & Feldman, J.F. (1989). Stability of behavior problems in very young children. Development and Psychopathology, 1, 5-19.
Rothbart, M. K., Ahadi, S. A., & Hershey, K. L. (1994). Temperament and social behavior in childhood. Merrill-Palmer Quarterly, 40, 21-39.
Rutter, M. (1997). Antisocial behavior: Developmental psychopathology perspectives.
In D. Stoff, J. Breiling, & J.D. Maser, (Eds.), Handbook of antisocial behavior (pp. 115-124). New York: John Wiley & Sons.
Rutter, M., Cox, A., Tupling, C., Berger, M., & Yule, W. (1975). Attainment and adjustment in two geographical areas: 1. The prevalence of psychiatric disorder. British Journal of Psychiatry, 126, 493-509.
Sameroff, A.J., Seifer, R., Barocas, R., Zax, M., & Greenspan, S. (1987). IQ scores of 4-year-old children: Social-environmental risk factors. Pediatrics, 79, 343-350.
Sanders, M. R., & Dadds, M. R. (1983). Behavioral family intervention. Needham Heights, MA: Allyn & Bacon.
Sanson, A., Oberklaid, F., Pedlow, R., & Prior, M. (1991). Risk indicators: Assessment of infancy predictors of pre-school behavioural maladjustment. Journal of Child Psychology and Psychiatry, 32, 609-626.
Shaw, D.S., Keenan, K., & Vondra, J.I. (1994). Developmental precursors of externalizing behavior: Ages 1 to 3. Developmental Psychology, 30, 355-364.
Shaw, D.S., Owens, E.B., Vondra, J.I., Keenan, K. & Winslow, E.B. (1996). Early risk factors and pathways in the development of early disruptive behavior problems. Development and Psychopathology, 8, 679-699.
Shaw, D.S., Winslow, E.B., Owens, E.B., & Hood, N. (1998b). Young Children's Adjustment to Chronic Family Adversity: A Longitudinal Study of Low-Income Families. Journal of the American Academy of Child and Adolescent Psychiatry, 37, 545-553.
Shaw, D.S., Winslow, E.B., Owens, E. B., Vondra, J.I., Cohn, J.F., & Bell, R.Q. (1998a). The development of early externalizing problems among children from low-income families: A transformational perspective. Journal of Abnormal Child Psychology, 26, 95-107.
Sroufe, L.A. (1983). Infant-caregiver attachment and patterns of adaptation in preschool: The roots of maladaption and competence. In M. Perlmutter (Ed.), Minnesota symposium in child psychology (Vol. 16, pp., 41-81). Hillsdale, NJ: Erlbaum.
Sroufe, L. A., & Rutter, M. (1984). The domain of developmental psychopathology. Child Development, 55, 17-29.
Thompson, R. A. (1994). Emotion regulation: A theme in search of a definition. In N. A. Fox (Ed.), The development of emotion regulation: Biological and behavioral considerations. Monographs of the Society for Research in Child Development (pp. 25-52). Chicago: University of Chicago Press.
Tremblay, R. (1998). On the origins of physical aggression. Presented at the meeting of the Life History Society, Seattle, WA.
van Ijzendoorn, M.H., Schuengel, C., & Bakermans-Kranenburg, M.J. (in press). Disorganized attachment in early childhood: Meta-analysis of precursors, concomitant, and sequelae. Development and Psychopathology.
Webster-Stratton, C. (1990). Long-term follow-up of families with young conduct problem children: From preschool to grade school. Journal of Clinical Child Psychology, 19, 144-149.
Webster-Stratton, C. & Herbert, M. (1994). Troubled families, problem children: Working with parents: A collaborative process. Chichester, England: John Wiley & Sons.
Zahn-Waxler, C., Iannotti, R.J., Cummings, E. M., & Denham, S. (1990). Antecedents of problem behaviors in children of depressed mothers. Development and Psychopathology, 2, 271-292.
Zeanah, C.H., Boris, N.W., & Scheeringa, M.S. (1997). Psychopathology in infancy. Journal of Child and Adolescent Psychology, 38, 81-99.