Temperament describes the stable, early-appearing individual variations in behavioral dimensions including emotionality (crying, laughing, sulking), activity level, attention, sociability, and persistence. The classic theory of Thomas and Chess proposes 9 dimensions of temperament (Table 6-1). These characteristics lead to 3 common constellations: (1) the easy, highly adaptable child, who has regular biologic cycles; (2) the difficult child, who withdraws from new stimuli and is easily frustrated; and (3) the slow-to-warm-up child, who needs extra time to adapt to new circumstances. Various combinations of these clusters also occur. Temperament has long been described as biologic or “inherited,” largely based on parent reports (although confirmed by some independent observational studies) of twins. Monozygotic twins are rated by their parents as temperamentally similar more often than are dizygotic twins. Estimates of heritability suggest that genetic differences account for approximately 20-60% of the variability of temperament within a population. It had been presumed that the remaining 80-40% of the variance was environmentally influenced because genetic influences tended to be viewed as static. We now know that genes are dynamic, changing in the quantity and quality of their effects as a child ages and thus, like environment, may continue to change. Longitudinal twin studies of adult personality indicate that personality changes largely result from non-shared environmental influences, whereas stability of temperament appears to result from genetic factors. Although associations between specific genes and temperament have been noted (a 48-base pair repeat in exon 3 of DRD4 has been associated with novelty seeking), such associations require replication studies before they can be viewed as causative.

Table 6-1 TEMPERAMENTAL CHARACTERISTICS: DESCRIPTIONS AND EXAMPLES *

CHARACTERISTIC	DESCRIPTION	EXAMPLES^†
Activity level	Amount of gross motor movement	“She’s constantly on the move.” “He would rather sit still than run around.”
Rhythmicity	Regularity of biologic cycles	“He’s never hungry at the same time each day.” “You could set a watch by her nap.”
Approach and withdrawal	Initial response to new stimuli	“She rejects every new food at first.” “He sleeps well in any place.”
Adaptability	Ease of adaptation to novel stimulus	“Changes upset him.” “She adjusts to new people quickly.”
Threshold of responsiveness	Intensity of stimuli needed to evoke a response (e.g., touch, sound, light)	“He notices all the lumps in his food and objects to them.” “She will eat anything, wear anything, do anything.”
Intensity of reaction	Energy level of response	“She shouts when she is happy and wails when she is sad.” “He never cries much.”
Quality of mood	Usual disposition (e.g., pleasant, glum)	“He does not laugh much.” “It seems like she is always happy.”
Distractibility	How easily diverted from ongoing activity	“She is distracted at mealtime when other children are nearby.” “He doesn’t even hear me when he is playing.”
Attention span and persistence	How long a child pays attention and sticks with difficult tasks	“He goes from toy to toy every minute.” “She will keep at a puzzle until she has mastered it.”

* Based on Chess S, Thomas A: Temperament in clinical practice, New York, 1986, Guilford.

^† Typical statements of parents, reflecting the range for each characteristic from very little to very much.

The concept of temperament can help parents understand and accept the characteristics of their children without feeling responsible for having caused them. Children who have difficulty adjusting to change may have behavior problems when a new baby arrives or at the time of school entry. In addition, pointing out the child’s temperament may allow for adjustment in parenting styles. Behavioral and emotional problems may develop when the temperamental characteristics of children and parents are in conflict.

Psychologic Influences: Attachment and Contingency

The influence of the child-rearing environment dominates most current models of development. Infants in hospitals and orphanages, devoid of opportunities for attachment, have severe developmental deficits. Attachment refers to a biologically determined tendency of a young child to seek proximity to the parent during times of stress and also to the relationship that allows securely attached children to use their parents to re-establish a sense of well-being after a stressful experience. Insecure attachment may be predictive of later behavioral and learning problems.

At all stages of development, children progress optimally when they have adult caregivers who pay attention to their verbal and nonverbal cues and respond accordingly. In early infancy, such contingent responsiveness to signs of overarousal or underarousal helps maintain infants in a state of quiet alertness and fosters autonomic self-regulation. Contingent responses (reinforcement depending on the behavior of the other) to nonverbal gestures create the groundwork for the shared attention and reciprocity that are critical for later language and social development. Children learn best when new challenges are just slightly harder than what they have already mastered; a degree of difficulty dubbed the “zone of proximal development.” Psychologic forces, such as attention problems or mood disorders, will have profound effects on many aspects of an older child’s life.

Social Factors: Family Systems and the Ecologic Model

Contemporary models of child development recognize the critical importance of influences outside of the mother-child dyad. Fathers play critical roles, both in their direct relationships with their children and in supporting mothers. As traditional nuclear families become less dominant, the influence of other family members (grandparents, foster and adoptive parents, same-sex partners) becomes increasingly important. In addition, children are increasingly raised by unrelated caregivers while parents work or while they are in foster care.

Families function as systems, with internal and external boundaries, subsystems, roles, and rules for interaction. In families with rigidly defined parental subsystems, children may be denied any decision-making, exacerbating rebelliousness. In families with poorly defined parent-child boundaries, children may be required to take on responsibilities beyond their years, or may be recruited to play a spousal role.

Individuals within systems adopt implicit roles. For example, one child may be the troublemaker, whereas another is the negotiator and another is quiet. Birth order may have profound effects on personality development, through its influence on family roles and patterns of interaction. Families are also dynamic. Changes in one person’s behavior affect every other member of the system; roles shift until a new equilibrium is found. The birth of a new child, attainment of developmental milestones such as independent walking, the onset of nighttime fears, and the death of a grandparent are all changes that require renegotiation of roles within the family and have the potential for healthy adaptation or dysfunction.

The family system, in turn, functions within the larger systems of extended family, subculture, culture, and society. Bronfenbrenner’s ecologic model depicts these relationships as concentric circles, with the parent-child dyad at the center (with associated risks and protective factors) and the larger society at the periphery. Changes at any level are reflected in the levels above and below. The shift from an industrial economy to one based on service and information is an obvious example of societal change with profound effects on families and children.

Unifying Concepts: The Transactional Model, Risk, and Resilience

The transactional model proposes that a child’s status at any point in time is a function of the interaction between biologic and social influences. The influences are bidirectional: Biologic factors, such as temperament and health status, both affect the child-rearing environment and are affected by it. A premature infant may cry little and sleep for long periods; the infant’s depressed parent may welcome this good behavior, setting up a cycle that leads to poor nutrition and inadequate growth. The child’s failure to thrive may reinforce the parent’s sense of failure as a parent. At a later stage, impulsivity and inattention associated with early, prolonged undernutrition may lead to aggressive behavior. The cause of the aggression in this case is not the prematurity, the undernutrition, or the maternal depression, but the interaction of all these factors (Fig. 6-2). Conversely, children with biologic risk factors may nevertheless do well developmentally if the child-rearing environment is supportive. Premature infants with electroencephalographic evidence of neurologic immaturity may be at increased risk for cognitive delay. This risk may only be realized when the quality of parent-child interaction is poor. When parent-child interactions are optimal, prematurity carries a reduced risk of developmental disability.

Figure 6-2 Theoretical model of mutual influences on maternal depression and child adjustment.

(From Elgar FJ, McGrath PJ, Waschbusch DA, et al: Mutual influences on maternal depression and child adjustment problems, Clin Psychol Rev 24:441–459, 2004.)

Buy Membership for Pediatrics Category to continue reading. Learn more here