Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 93
From Neurons to Neighborhoods: The Science of Early Childhood Development 5 Acquiring Self-Regulation Human infants start life as remarkably helpless individuals who elicit powerful protective responses from their caregivers. On their own, they would die. In relationships with protective, nurturing adults, they thrive. Supporting their development, however, requires sustained patience and adaptation as infants move gradually and unevenly from needing help in order to do anything, to doing—and even insisting on doing—many things for themselves. Scientists have found it useful to capture this transition from helplessness to competence in terms of the child's growing regulatory capacity. What does this mean? Initially, it refers to the mastery of tasks that were accomplished by the mother's body or in concert with the mother's body when the child was in the womb, but now must be accomplished by the child's body and through signaling needs to responsive adults. These tasks include everything from maintaining a normal body temperature to orchestrating physiology and behavior to conform to the day-night rhythm of human existence, to learning to soothe and settle once basic needs are met. Later, it means developing the capacity to manage powerful emotions constructively and keep one's attention focused. This chapter addresses these regulatory tasks. Regulation cuts across all aspects of human adapatation. Living and learning require people to react to changing events and then to regulate their reaction. The capacity to react and the toll that reaction takes depend on the capacity to recover from the reactions. For example, getting upset by things that are upsetting can be very useful. It motivates people to act to make life better. But staying upset, ruminating, or carrying negative emo-
OCR for page 94
From Neurons to Neighborhoods: The Science of Early Childhood Development tions around like a talisman can be very destructive to oneself and others. Mobilizing efforts to explore a new problem or situation is very important and useful; staying mobilized while working on a problem to the point of exhaustion and collapse is unhealthy. Adequate adaptation and development require reaction and regulation. Infants and young children are often good at the reaction part, but need help with regulation. Children increasingly develop the ability to regulate their reactions, particularly in supportive environments. To reiterate one of our core concepts, development may be viewed as an increasing capacity for self-regulation, seen particularly in the child's ability to function more independently in a personal and social context. Reaction and regulation can be seen in all aspects of life, from the capacity to work harder when one is rested better to the capacity to fight diseases better when one is able to both turn on and turn off the immune system more efficiently. Regulation in early development is deeply embedded in the child's relations with others. In caring for infants, parents are acting as extensions of their internal regulatory systems. Establishing the connection between parent and child can be seen as the basic task of the early months of life. Making that connection is not always easy, however. It requires the ability to read and understand the baby's needs and the knowledge, energy, and resources to respond in ways that are helpful. Providing the experiences that allow children to take over and self-regulate in one aspect of their lives after another is a very general description of the job of parents, teachers, and protectors of children that extends throughout early childhood and into the adolescent years. The first step in the earliest days of children's lives is to establish regulatory connections with them and then gradually shift the responsibility of regulation over to them in the day-to-day domains of sleeping, waking, and soothing. In this chapter, the development of self-regulation is profiled with respect to managing physiological arousal, emotions, and attention. These are fundamental tasks for the early years, but they entail very different influences and developmental processes. The reason for considering each a component of developing self-regulation is that these are the earliest ways that infants and toddlers learn to manage themselves and begin to acquire the behavioral, emotional, and cognitive self-control that is essential to competent functioning throughout life (Bronson, 2000; Kopp, 2000). Each is important also because it reflects the growing maturity and integration of several brain areas (particularly in the frontal regions) that enable increased self-monitoring and deliberate inhibition of undesired behavior (Diamond, 1996; Diamond and Taylor, 1996; Diamond et al., 1994). These neurobiological changes are consistent with the common observation that, between birth and age 6, children become increasingly proficient at exercising self-control and applying rules consistently to their own
OCR for page 95
From Neurons to Neighborhoods: The Science of Early Childhood Development behavior, whether this is manifested in their success at “Simon Says,” their ability to wait for a cookie, their capacity to remain quiet and still during religious services, or their capacity to ignore distractions while concentrating on a task. Further advances in the same brain regions are thought to be related, at older ages, to the growth of higher-level reasoning, problem solving (Case, 1992), and planning and executing complex actions, sometimes called “executive control” (Stuss, 1992), which we profile in the final section of this chapter. EARLY REGULATORY TASKS Some cultures celebrate a child's first birthday at about 3 months after birth. This recognizes the fact that the child's life history began at conception. But interestingly, it also corresponds to what has been called the first biobehavioral shift in development (Emde et al., 1976). Between 3 and 4 months after birth, there are marked changes in almost every aspect of infant functioning, from the electrical patterns of brain activity (EEG) (Emde et al., 1976) to the regulation of visual attention (Rothbart et al., 1994a). Sharper focus on the first 3 months of life suggests that the entire period is one of transition, as the baby's behavior and physiology shift from intrauterine to extrauterine regulation (Mirmiran and Lunshof, 1996). The full-term newborn of normal weight comes into the world well-prepared to negotiate this transition. As with all developmental tasks, however, cultural variations in caregiving practices and individual family differences within cultures affect how this early transition is worked through. The full range of childrearing practices around the world appears to confront newborns with markedly different contexts in which to manage the transition from intra- to extrauterine regulation (Barr et al., 1987). Nevertheless, babies adapt, and indeed thrive, in a wide variety of culturally normative caregiving niches. This theme of developmental adaptation within cultural variation applies to virtually all developmental tasks for which we have pertinent data. Take the !Kung San—a hunter-gatherer culture from the Kalahari Desert—as an example. The young infant is in constant skin-to-skin contact with her mother, sleeping with her at night and being carried continually during the day. She is fed breast milk in small amounts approximately every 15 minutes. Fusses are responded to immediately before they build to cries. Little or no emphasis is placed on getting the baby to sleep through the night. At arguably the other extreme, in North America and Europe, early care typically separates the baby from the caregiver for varying periods of the day and night. Feedings are larger but more widely spaced. Not all cries, and certainly not all fusses, are responded to immediately. And
OCR for page 96
From Neurons to Neighborhoods: The Science of Early Childhood Development there is a strong emphasis on encouraging day-night behavioral organization and sleeping through the night. Although intriguing, there are few data on whether or how these different practices influence children's development in the long term. In the short term, it seems likely that both cultural and individual differences in caregiving influence what caregivers view as regulatory problems in this early period. Unfortunately, most of what is known about this has been based on studies in North America and Europe, where two regulatory concerns permeate the pediatric and child development literature: (1) concerns about establishing day-night rhythms, typically labeled “sleep problems” (Anders, 1979) and (2) concerns about excessive crying (Barr, 1993; Keefe, 1988; St. James-Roberts and Halil, 1991). These concerns, however, take different forms even within European-American cultures, as illustrated by comparisons between Dutch and U.S. (white) mothers (Super et al., 1996). While concerns about their child's sleep patterns were much more evident among the Dutch mothers, who focused on their own role in imposing regularity on sleep times, the U.S. mothers were much more likely to use the terminology of “problems” when discussing their child's sleep and to ascribe the problems to innate tendencies of the child rather than to their own parenting practices. While parents raise issues about sleep and crying throughout infancy, they are particularly evident during this early birth-to-3-month transition period. Much of the research on these concerns has focused on identifying the underlying pathology in the child (Lehtonen et al., in press), yet there is very little evidence that early sleep and crying problems strongly predict later physiological or behavioral problems for otherwise healthy, full-term babies (Elliot et al., 1997; Rautava et al., 1995; Stifter and Braungart, 1992). This has led to a more recent, albeit still controversial, approach that views these problems not as expressions of infant pathology, but as reflections of how normal individual differences are expressed when infants attempt to accomplish early regulatory tasks in the context of the dominant North American/European style of caregiving (Barr, 1990). This perspective shifts the unit of interest from the baby to the family, and from the behavior (i.e., crying per se) to what the behavior sets in motion within the family (Papoušek and von Hofacker, 1998; St. James-Roberts et al., 1995a; Stifter and Bono, 1998). There is, in fact, some evidence in support of this more dynamic perspective. These early sleep and crying problems can pose serious challenges to parents, which create tension among family members, fuel negative perceptions of the infant, and undermine the parents' confidence in their caregiving abilities. These detrimental repercussions remain measurable, at least in some families, later in infancy after the precipitating behavior has largely passed (Papou šek and von Hofacker, 1998; Raiha et al., 1995; Rautava et al., 1995).
OCR for page 97
From Neurons to Neighborhoods: The Science of Early Childhood Development The regulatory challenges of this period are heightened for premature or medically fragile infants (see Chapter 8 for a fuller discussion). There is a general consensus that the lower the birthweight, the more difficult the adjustment to extrauterine life, especially for the babies who are small for their gestational age and for those born to mothers with low educational attainment (Georgieff et al., 1989; Ment, 2000; Saigal et al., 1991). Among very-low-birthweight infants, there are the added risks of serious medical conditions and long stays in neonatal intensive care nurseries. Thus, each partner contributes vulnerabilities to the establishment of the mother-infant dyadic relationship. It is easy to understand that the mother would be stressed and anxious. The infant, in addition, tends to be much less adept than the normal newborn in organizing and stabilizing biological rhythms of sleep, waking, and feeding. He is likely to be more unpredictable, to be fussier during social interactions, to make less eye contact, to smile less, to vocalize less, and to show less positive affect—in other words, to be more difficult and harder for the parent to read (Beckwith and Rodning, 1992; Barnard and Kelly, 1990). Under these circumstances, the caregiver 's ability to respond sensitively and to cooperate with the infant 's ongoing behavior can be seriously compromised. But even here, a shift in emphasis from focusing on what is wrong with the baby to identifying caregiving strategies that provide support for the child 's emerging regulatory competencies can be most helpful. Because early intervention efforts, such as home visiting, often begin during this period, accurate information about early regulatory challenges may help service providers short-circuit potential corollary problems. Looking in more depth at what is now known about day-night rhythms and crying can expand the focus from the problem of getting the infant to sleep or stopping the infant from crying, to a better appreciation of the magnitude of the task that the infant is attempting to accomplish, individual differences in how infants respond during this time of transition, and the contribution of caregivers' responses to the success with which these transitions will be made. Accomplishing early regulation is an example of how the outcomes of developmental processes depend on the relationship between children and their caregivers. Acquiring Day-Night Wake-Sleep Rhythms Humans are diurnal beings who are typically active during the day and quiet at night. Through eons of evolution, human physiology has come to reflect this day-night rhythm (Moore-Ede, 1986). Day-night rhythms are due to both endogenous factors (clocks inside the body) and exogenous influences (the day-night rhythms in the physical and social world) (Ikonomov et al., 1998). The internal clock lies deep in the brain in a part
OCR for page 98
From Neurons to Neighborhoods: The Science of Early Childhood Development of the hypothalamus called the suprachiasmatic nucleus (Dickstein et al., 1998a). It receives information about what time it is outside the body, generates signals that set the timers or pacemakers of different systems, and coordinates or synchronizes those various systems. Newborns don't seem to know day from night (Anders, 1975). Is this because their internal clocks aren't fully mature? Is it because these clocks, although fully mature, still need to be set to the light-dark, activity-rest periods of family life? Does the fact that the newborn's energy needs require her to eat in the middle of the night keep her clocks from generating robust day-night rhythms (Wright et al., 1983)? Is she working on pulling together and orchestrating the rhythms of multiple systems—temperature, blood pressure, hormone, kidney, liver—that are themselves still maturing (Price et al., 1983)? We do not know the full answers to any of these questions yet. However, this list, which could be much longer, gives some of the flavor of the complexity of the task that faces both the newborn and the family in sorting out how to differentiate day from night. Something is known about the facet that affects parents the most: infant sleep-wakefulness (Coons and Guilleminault, 1982; Elligson and Peters, 1980; Schectman et al., 1994). Both the structure and temporal organization of sleep evolves rapidly in the first 3 to 4 months after birth (Anders, 1975; Elligson and Peters, 1980; Gehart and Maccoby, 1980). Newborns sleep a lot, typically 16-17 hours per day (Coons and Guilleminault, 1982; Hoppenbrouwers et al., 1982), and the structure of sleep-wakefulness more strongly reflects a basic 90-minute rest-activity cycle than it does a day-night rhythm (Anders, 1982; Coons and Guilleminault, 1982). Total sleep time decreases to about 14-15 hours by 3 months, and sleeping and waking bouts begin to lengthen and consolidate (Anders et al., 1992; Bernal, 1973; Coons and Guilleminault, 1982). At birth, the longest sleeps last about 4 hours, while by 3 months they can be as long as 8 to 10 hours and, for most babies, they occur during the night (Anders et al., 1992; Bernal, 1973). Like adults, during long periods of sleep, babies drift up to brief periods of waking or near waking. Videotaped studies of infant sleep suggest that one big difference between babies who sleep through the night and those who don't is what happens during these brief waking periods (Anders et al., 1992). Babies who sleep through rouse briefly and then settle themselves back into sleep, while those who don't then cry out and waken their parents. There is some evidence that babies who fall asleep in their cribs establish patterns of self-settling, while those who fall asleep in contact with a parent signal when they wake to circumstances that are different from those when they fell asleep. Patterns of feeding also influence nighttime signaling (and thus parental sleeping through the night) (Wright et al.,
OCR for page 99
From Neurons to Neighborhoods: The Science of Early Childhood Development 1983). Bottle-fed babies lengthen the duration of their longest bout of sleep a bit faster than do breast-fed babies. While this can sound attractive to the sleep-disrupted parent, bottle-fed babies also get sick more than do breastfed babies (Beaudry et al., 1995). Because the rhythms of other systems, like growth hormone, cortisol, body temperature, and so on, are orchestrated in relation to sleep, many suspect that the development and organization of sleep helps orchestrate the day-night rhythms in these other systems (Finkelstein, 1971; Koob, 1992; Weitzman et al., 1979). Poets and philosophers have long been intrigued by the similarities between sleep and death. Parents find these similarities more terrifying than intriguing. Many a parent has probably poked or nudged his or her soundly sleeping infant to bring about reassuring signs of life. Although controversial, some suspect that the shorter bouts of sleep characteristic of early infancy may be protective for babies whose neural systems regulating breathing, swallowing, and airway clearing are still maturing (McKenna, 1990; Trevathan and McKenna, 1994). Concerns that very young babies will sleep so deeply that they will fail to react when air is blocked and oxygen levels get too low have led to the recent pediatric advice to avoid placing babies on their stomachs during sleep (American Academy of Pediatrics Task Force on Infant Positioning and SIDS, 1992). Similar concerns have led researchers to reexamine what happens when babies sleep alone and when they sleep with others (i.e., cosleeping) (McKenna et al., 1993, 1994). Mothers and their 3-month or older infants have been brought into sleep laboratories, where brain waves, heart rate, and respiration for both mother and infant can be monitored throughout the night. Perhaps not surprisingly, mothers and babies don't sleep as soundly when they sleep together. Because both breast-feeding and cosleeping induce shorter bouts and less sound nighttime sleep, several researchers have speculated that they protect the very young baby from such things as sudden infant death syndrome (SIDS) (McKenna, 1990; McKenna and Mosko, 1990). This is virtually impossible to prove. Nevertheless, differences in cultural practices surrounding cosleeping and breast-feeding abound. In this context, it may be useful to think broadly about how culturally normative variations mesh with the infant's developing capacities. On one hand, it is instructive to recognize that human infants have remarkable capacities to adapt to a wide range of caregiving practices. On the other hand, understanding practices that have evolved and been sustained around the world, but are less common in the United States, can be extremely valuable. Cultural differences are not arbitrary, nor do they reflect any simple translation from beliefs into practices; rather they reflect different trade-offs among several goals that can, in turn, have differing consequences for the infant.
OCR for page 100
From Neurons to Neighborhoods: The Science of Early Childhood Development Learning to Regulate Crying Crying serves to signal caregivers. Infants of many species produce calls that serve similar functions. However, only humans cry for no reason at all (paroxysmal crying) and keep crying after being picked up, fed, and otherwise apparently made comfortable (Barr, 1990). Folk wisdom says that there are hunger cries, pain cries, irritable cries, and so on. In fact, when one hears cries out of context, the likelihood of identifying the cause of the cry is very poor (Green et al., 1995). Beyond what is causing crying, caregivers usually want to know how to stop the cries and soothe the infant. Although there are marked cultural variations in beliefs about responding to all fusses and cries, once people do respond, they follow remarkably similar soothing patterns (Barr, 1990). They say something, touch, pick up, search for sources of discomfort, and then feed. Parents run through this repertoire so often in those early weeks and months of a baby's life that they could do it in their sleep—and often do, or so it seems. Infants cry in all of the cultures that have been studied, and interestingly, crying follows a similar developmental course (Barr, 1990; Barr et al., 1987, 1996). In caregiving settings as different as the !Kung and North America, crying makes up more and more of the baby's (and caregiver's) day until it peaks, often around 6 to 8 weeks, and then begins to decline (with the timing of the peak and decline varying for different babies). But cultural variations in caregiving practices may influence the amount of crying that characterizes infants. Comparing the !Kung and North American and Northern European babies, although crying peaks at about the same time, !Kung babies cry less, even at their peak. Furthermore, it is not that !Kung babies cry less often, rather that they are soothed more quickly. Researchers in Canada tested whether they could help North American babies settle more readily by providing them with more of a !Kung-like caregiving experience (Hunziker and Barr, 1986). They randomly assigned families to a condition in which caregivers increased by 2 hours how much they carried the baby each day. Compared with babies in the control condition (in which caregivers kept on with their regular practices), babies who were carried around more shifted their crying toward the !Kung level of the curve. They did not cry less often, but began to be soothed more quickly. Unfortunately, the rather dramatic results of this study were not replicated when something similar was tried in England (St. James-Roberts et al., 1995b). The Canadian and English studies weren't identical, and researchers are still puzzling over whether the differences (in baby slings/packs, instructions to families, control group rates of carrying, or something else) might explain the lack of replication. This failure to replicate, however, probably suggests what parents have long suspected—there is no magic bullet, except perhaps time. By 12 to 16 weeks, most babies have
OCR for page 101
From Neurons to Neighborhoods: The Science of Early Childhood Development settled down, spend less of their days crying, seem easier to read, and much easier to soothe. There is also some evidence that individual differences in caregiving can affect crying in the earliest months of life. Babies whose caregivers have been responsive to their distress and sensitive in reading the meaning of their somewhat ambiguous cry communications shift more smoothly into patterns of noncrying communication and spend more time in happier, less distressed states as the first year proceeds (Crockenberg, 1981). This may sound like babies have never heard of the laws of learning (i.e., reward the behavior and it should increase). However, babies who are never responded to, such as those who grow up in institutions, often cease crying almost completely by about the time they are 3 months old. Babies evidently do learn to stop crying if it is never “rewarded.” The laws of learning actually say that the most powerful way to keep a behavior going is to reward it sometimes and not others, termed “intermittent reinforcement.” The laws of learning would argue that less, but intermittently, responsive parenting should create a baby who is more fussy and whiny. This, indeed, appears to be the case. The evidence that responding consistently and readily to the infant's cries reduces crying in the long run is not as strange as it first seems. Not all crying is the same. Some parents live in dread of having an infant with colic. Colic is a syndrome that has perplexed parents and physicians for ages. It describes a syndrome of excessive, uncontrollable crying that, following the normal crying curve, also peaks around 6 to 8 weeks and resolves between 12 and 16 weeks (with lots of variation among babies in timing and duration) (Barr et al., 1992; Karofsky, 1984; Miller and Barr, 1991). Like other crying, it also clusters in the late afternoon and evening hours. It differs from noncolic crying primarily in being difficult if not impossible to soothe. Somewhat arbitrarily, colic is often defined for research purposes by Wessel's rule of three: fussing or crying for more than 3 hrs/day, for 3 days/week, for 3 weeks (Wessel et al., 1954). How much a baby with colic cries varies from one day to the next, and from one baby to the next. Using diaries kept by parents in which they record each crying bout of 5 minutes duration or more, the crying of infants with colic has been documented to vary from 3 hrs/day to as much as 6 or more hrs/day. This compares to the 1 to 2 hrs/day of crying that parents report for babies without colic. At its worst, a baby with colic may cry most of the time she's awake, and, adding insult to injury, she seems to sleep less than babies without colic (Lehtonen et al., 1994). The word colic refers to what has seemed to be the obvious source of this crying: something to do with the digestive system. However, despite many attempts to identify what is wrong with the baby (i.e., sensitivity to cow's milk protein, incomplete lactose absorption, gastroesophageal reflux, gastrointestinal immaturity, including allergic reactions) thoughtful reviews
OCR for page 102
From Neurons to Neighborhoods: The Science of Early Childhood Development of the data suggest that no more than 5 percent of colic can be attributed to identifiable pathologies (Gormally and Barr, 1997). That's not much, especially considering that the rate of colic may be as high as 10 to 20 percent in Western cultures. Even if convinced that babies with colic are not suffering from a physical disorder, scientists, like the parents, wonder about its implications for who the baby is and who she will become. By definition, infants with colic are difficult. But does this mean that they are biologically or constitutionally predisposed to have difficult, irritable temperaments once the colic has passed? The weight of the evidence suggests that this is not true (Elliot et al., 1997; Rautava et al., 1995; Stifter and Braungart, 1992), but there is still argument over this conclusion primarily because of the difficulty of measuring both crying and temperament. It must be a relief to parents of babies with colic to find that, by about 3 to 4 months, they have an emotionally quite different baby on their hands. No longer irritable or hard to soothe, the baby 's true temperament begins to be more apparent. This is true not only of infants with colic. In general, it is difficult to predict later temperament from behavior in the first 3 to 4 months of life, as infants are going through so many transitions. Stability in infant temperament appears to increase by 4 months of age. Recently, developmental psychologists have become quite interested in identifying the roots of a temperamental pattern that is known as behavioral inhibition. Inhibited toddlers and preschoolers are very shy in social encounters (Calkins et al., 1996; Rubin et al., 1997), wary of and upset by novel stimuli, and are thought of by parents and peers as anxious and fearful (García Coll et al., 1984). The impetus for this interest is twofold. First, there is growing concern with understanding the developmental pathways that lead to later anxiety and depressive disorders. Second, neuroscience research is revealing the specific neural pathways and neurochemical processes that underlie fear responses. This work is suggesting hypotheses about why some children may be extremely anxious and fearful from an early age. This has led to several programs of research (see Fox et al., in press; Kagan and Snidman, 1991; Kagan et al., 1998) on young children who display fearful, shy, inhibited temperaments to identify both the antecedents and consequences of these characteristic patterns of responding to people and events. Kagan and his colleagues developed a set of challenges for 4-month-olds that included highly stimulating sounds, sights, and smells that are presented to the baby in a set order. Some babies think these stimuli are great. They smile, coo, and wave their arms around as if to say, “Give me more!” At the other end of the spectrum, some babies find the stimulation to be too much. They fuss, arch their backs, cry, and struggle, as if to say, “Take them away! ” When babies are tested at 2 months, how they react to these challenges doesn't predict later temperament. However,
OCR for page 103
From Neurons to Neighborhoods: The Science of Early Childhood Development by 4 months, reliable differences emerge. Babies who react positively are more likely to become busy, active, boisterous toddlers—some would say a handful, others refer to them as exuberant. In contrast, those who find the stimulation to be too much are more likely to be fearful and shy as toddlers and preschoolers. This evidence suggests that, for some children, negative reactivity to novel stimuli as infants evolves into a shy, inhibited, anxious temperamental pattern by toddlerhood. This is not a trivial phenomenon. About 20 percent of healthy, European-American samples display negative reactivity to novel stimuli as young infants (Kagan et al., 1998). About one-third of the reactive infants studied by Kagan and his colleagues remained highly fearful of unfamiliar events at 14 and 21 months, and 13 percent of these infants continued to show subdued and shy behavior with unfamiliar adults and peers at 4 ½ years of age (Kagan et al., 1998). At age 6, the inhibited children continued to be socially wary and reticent during their interactions with peers and an adult experimenter, and they exhibited signs of physiological stress (Kagan et al., 1987). Researchers who have focused on the socially reticent behavior of these children have found contemporaneous associations with maternal reports of both shyness and internalizing behavior problems (Coplan et al., 1994). Recently, inhibited temperamental patterns have been associated with a physiological pattern of resting right frontal EEG activation (Calkins et al., 1996; Fox et al., 1995, 1996; Schmidt and Fox, 1994), which appears to be associated with a tendency to respond to stressful events with negative affect or depressive symptomatology (Davidson, 1992). Fox and his colleagues (in press) have recently linked this physiological pattern at 9 months of age to continuity in behavioral inhibition up to age 4. We refer to the same physiological pattern when we discuss the developmental consequences of maternal depression in Chapter 9. Once caregivers and babies have ridden the roller-coaster of rapid developmental change through the first 3 months of life and the baby 's behavioral style or temperament seems to be easier to discern, the next task is to support the baby's developing abilities to regulate his or her emotions and behavior. Although learning to sleep through the night might seem far afield from controlling outbursts of emotion, learning to wait before acting, self-monitoring, and acquiring the ability to organize segments of behavior sequentially—all of which are embraced by the term “self-regulation”—they all involve various forms of self-monitoring and response inhibition that, in turn, reflect the growing maturity of the brain, as we discussed at the beginning of this chapter. The infant's emerging ability to replace crying with other forms of communication is just the first step along a developmental progression that recruits the child's increasing competencies into more and more mature self-regulatory functioning.
OCR for page 113
From Neurons to Neighborhoods: The Science of Early Childhood Development pier as a result—but they also have an easier time relating to others at home, in child care, and on the playground, as we discuss in more detail in Chapter 7. Indeed, the close correspondence between emotion regulation and relationships with peers has critical implications for efforts to foster positive social interactions and help young children who have problems in this area. Acquiring the capacity to regulate emotions also helps children believe that emotions are manageable, controllable, and can be appropriately mobilized and expressed—in short, that one 's feelings need not be overwhelming, undermining, or disorganizing —what Saarni (1990, 1999) calls “emotional self-efficacy.” Children who do not feel in control of their emotions are more prone to outbursts, inattention, and rapid retreats from stressful situations, thereby creating a self-fulfilling prophecy (Garber et al., 1991). Finally, the capacity for self-regulation is a prerequisite for the critical task of learning to comply with both external and internalized standards of conduct (Zahn-Waxler and Radke-Yarrow, 1990; Zahn-Waxler et al., 1992). Compliance is dependent on the child 's ability to control his reactions, as well as his motivation to do so. Parents contribute in multiple ways to children's developing capacity for emotion regulation. As with the infant's emerging ability to regulate states like crying, the parents' role in socializing emotion regulation is one of gradually handing over the reins to the child. At first, parents and other caregivers intervene directly to soothe or pacify the infant, organizing the child's experiences around routines that are manageable and predictable. These behaviors lend predictability to the infant's world, reduce the emotional demands of daily experiences, and “scaffold” the infant's own efforts at emotion regulation. Later, parents and others coach children in strategies for mobilizing their emotions to fit the needs of a given situation, whether it involves comforting a hurt friend, learning to take turns, or dealing with the frustration of attempting a task that is just beyond their capabilities (Thompson, 1990). This involves a subtle blend of give-and-take with the child (i.e., you hide and learn that you can handle the anxiety of doing without me momentarily, and then I'll find you and dispel your anxiety), the provision of supportive challenges (i.e., this puzzle may be a little frustrating, but I 'll help you do it), and respect for the child's unique ways of dealing with emotions (i.e., I'll let you blow off some steam before I try to calm you down). Equally important, however, are the more subtle ways in which the reassurance that young children derive from their attachments to caregivers constitute an important resource for emotion regulation (Cassidy, 1994, 1995; Cassidy and Berlin, 1994; Nachmias et al., 1996). Emotion regulation is fostered, in other words, not only by the parent's immediate interventions but also by the security and confidence that the relationship with the caregiver inspires in children as they grapple daily with feelings that, initially without even a vocabulary to describe them let
OCR for page 114
From Neurons to Neighborhoods: The Science of Early Childhood Development alone strategies for managing them, can be confusing and frightening (Case, 1992; Diamond, 1996; Diamond and Taylor, 1996; Diamond et al., 1994; Johnson, M.H., 1998; Rothbart et al., 1990, 1994; Stuss, 1992). Parents, however, do not operate in a vacuum. Research is revealing the large extent to which the task of learning how to manage one 's emotions and integrate them into daily life is a different challenge for children with different temperaments, as well as for their parents. The ability to inhibit a response one is all set to perform, sometimes called effortful control, has been of special interest to researchers who seek to understand how individual differences in children's tendencies to respond to stressful or exciting events affect the growth of emotion regulation. Effortful control is one component of a larger set of inhibitory competencies, termed “executive functions,” discussed later in this chapter. Effortful control is what enables the preschooler to take a response that is “primed” and inhibit it. Examples include acting only when it is appropriate to the rules (such as when the game leader says “Green light!”), constraining negative emotional outbursts, and planning a long-term strategy for a desired reward (such as saving an allowance to buy a Nintendo game). A game like Red Light, Green Light or Simon Says, for example, involves getting one type of behavior going (like walking quickly to the finish line or doing whatever Simon says as fast as you can) and then suddenly inhibiting or stopping those actions. Doing well at these games requires paying sharp attention for a long time, keeping track of the rules of the game, and interrupting actions that you are all set to perform. The more excited children get about playing these games, the harder it is for them to play them well. The faster they get going, the harder it is to stop. In the language used at the beginning of this chapter, the stronger the reaction, the greater the challenge for regulation. The ability to play these games (and to use these competencies in general) seems to involve the development of structures in the prefrontal areas of the brain (Rothbart et al., 1995). An area of the frontal lobe called the anterior cingulate gyrus becomes very active any time one effortfully attempts to inhibit a thought or action for which one is primed. This area of the brain, like many areas in the frontal lobe, develops slowly over the course of childhood. People get better at performing the cognitive tasks that involve the anterior cingulate as they get older, and they also get better at controlling their emotional expressions as they get older. What researchers are now trying to determine is whether these two phenomena go together. Children of the same age exhibit differences in behaviors that should reflect the development of the frontal lobe. Parents and teachers report that some children are better than others at inhibiting inappropriate behavior, playing games like Red Light, Green Light and so on. So far, for normally developing children, the most evidence that effortful control is
OCR for page 115
From Neurons to Neighborhoods: The Science of Early Childhood Development involved in emotion regulation comes from studies using parent and teacher questionnaires and observational tasks (i.e., not peeking while an experimenter wraps a present for you) involving behaviors that should reflect these competencies. There is very little evidence as yet that relates data obtained from these methods to activity in the anterior cingulate or other areas in the frontal lobes. Thus, the link to brain development is still only a theoretical one. Children develop effortful control competencies gradually over the preschool years, and the full expression of these competencies requires development that extends into adolescence. From early in their development, some children seem to be better at effortful control than others, and there appears to be reasonable stability in this aspect of temperament and regulatory capacity (Kochanska et al., 2000). There is also growing evidence that individual differences in these capacities have meaningful implications for several aspects of early development that parents and others who work with young children care a great deal about. For example, young children who are higher on measures of effortful control tend to perform better on measures of early conscience and moral behavior (Kochanska et al., 1996, 1997). Conversely, infants and young children who have difficulties with inhibiting more compelling, negative impulses also tend to elicit aversive responses from others which, in turn, recreate precisely the kinds of experiences that lead to impulsive and negative behaviors (Rothbart and Bates, 1998). Not surprisingly, children who are not good at effortful control have a hard time with peer relations (see Chapter 7). In each of these examples, the response biases that come with a young child's unique temperamental profile provide the intrinsic context within which developing capacities for self-regulation emerge. In sum, self-regulatory skills have important implications for how well children negotiate many other tasks of early childhood. Identifying and intervening with children who need extra help in developing these competencies may be important. However, determining who really needs help, as opposed to just more time to grow up, may be difficult. Furthermore, it seems possible that children who have more to regulate (i.e., those who are more exuberant and more active, more anxious and inhibited) may appear to be delayed or deficient in self-regulatory abilities, when in fact they are not. They may simply need to reach more mature levels of these abilities to be able to adequately manage who they are. REGULATION OF ATTENTION AND EXECUTIVE FUNCTION Just as infants and young children must learn to control their emotions, they must also learn to control behavior and regulate mental processes. The ability to think, retrieve, and remember information, solve problems,
OCR for page 116
From Neurons to Neighborhoods: The Science of Early Childhood Development and engage in other complex symbolic activities involved in oral language, reading, writing, mathematics, and social behavior is dependent on the development of attention, memory, and executive function (Lyon, 1996). Difficulties with these more cognitive aspects of self-regulation can lead to problems in school, in relationships, and in life. Self-regulation of attention and cognitive abilities is often described as a form of executive function. Executive function is an umbrella term used to refer to a variety of interdependent skills that are necessary for purposeful, goal-directed activity, such as learning to hold a crayon and scribble on paper, string beads, or hand a cup of juice to a friend without spilling (e.g., Luria, 1966; Shallice, 1982). To engage in these sorts of behaviors, the child must be able to deploy a series of relatively complex skills. They include generating and maintaining an appropriate mental representation that guides goal attainment (“I need to hold up the string and put the end through the hole in the bead”), monitoring the flow of information about one's progress (“I've got one on, now I'll try another”), and modifying and flexibly adapting problem-solving strategies so that behavior is continually directed toward the goal (“Oops, that bead was too hard to string; maybe I need to find a bead with a bigger hole”). These skills are needed whether the task involves correctly sorting colored blocks, gaining entry to a peer group, or successfully riding a tricycle. The construct of executive function is difficult to define, in part, because executive function, attention, and memory are interdependent and have fuzzy boundaries (Lyon, 1996). Despite difficulty in establishing a clear definition, there is growing consensus among researchers as to what executive functions entail: self-regulation, sequencing of behavior, flexibility, response inhibition, planning, and organization of behavior (see Eslinger, 1996). Control and modulation of behavior are fostered by the abilities to initiate, shift, inhibit, sustain, plan, organize, and strategize (Denckla, 1989). Emerging Capacities for Executive Functioning Early researchers did not study executive functioning in young children, believing that executive skills were not functional until the brain reached maturity in adolescence (Golden, 1981). It is now generally recognized that early precursors of these skills are present in infancy (Welsh and Pennington, 1988), and there is a growing body of research that demonstrates that performance on executive tasks improves in a stage-like manner that coincides with growth spurts in frontal lobe development during infancy and through the early childhood years (Anderson, 1998; Bell and Fox, 1992, 1994; Levin et al., 1991; Posner et al., 1998; Thatcher, 1991; Welsh and Pennington, 1988). This evidence for the early emergence of executive skills is further supported by findings from the neuropsychologi-
OCR for page 117
From Neurons to Neighborhoods: The Science of Early Childhood Development cal literature that link deficits in executive function to early frontal lobe dysfunction (Benton, 1991; Eslinger and Grattan, 1991; Tranel et al., 1994). What are the first signs of emerging executive skills, and when do they develop? At a very basic level, executive functions cannot emerge before the child is able to orient to relevant and important features in the environment, anticipate events, and represent the world symbolically (Barkley, 1996; Borkowski and Burke, 1996; Denckla, 1996; Pennington et al., 1996). Recent methodological advances have made it possible to study some elements of these abilities in infants. For example, Haith and his colleagues have demonstrated that infants as young as 6 weeks are capable of anticipating a sequence of events (Dougherty and Haith, 1997; Haith and McCarty, 1990; Haith et al., 1988). When they are shown pictures that appear and disappear in predictable locations at predictable times, 6-week-old infants quickly form expectations and demonstrate they can anticipate the location of the next picture by shifting their eyes to the predicted location before the picture appears (Haith et al., 1988). The ability to make anticipatory eye movements using these simple sequences improves with age, becoming consistent by 3 1/2 to 4 months (Haith et al., 1988; Johnson et al., 1991), but then it reaches a plateau in which there is no improvement between 4 and 10 months (Posner et al., 1997). It is not until age 18 months that infants can anticipate ambiguous, context-dependent sequences (e.g., learning to look at a target that moved from location 1 to location 2 and then back to locatoin 1 before moving to location 3) that would require focused attention in adults (Posner et al., 1997). These emerging abilities to control attention underlie the development of executive functions that entail, for example, planning and executing sequences of behavior. Means-ends behavior, another precursor to executive functioning, commonly emerges around ages 8 to 12 months, when the infant will, for example, remove an obstacle to retrieve a toy (Piaget, 1952). Research aimed at linking the emergence of goal-directed behavior to early brain development has provided evidence that frontally mediated, goal-directed, planful behavior is present as early as 12 months in infants (Diamond, 1988; Diamond and Goldman-Rakic, 1989; Goldman-Rakic, 1987). At about the same time, children learn to use language and to represent the world through symbols. Symbolic representation and language are the means through which a child can link the present with past knowledge and a future goal (e.g., Baron and Gioia, 1998; Kopp, 1997). They are believed to be the cornerstone for working memory and a necessary component for executive problem solving (Goldman-Rakic, 1987). A third skill that emerges in infancy and continues to develop through childhood is self-control (Kopp, 1982). Research on self-control examines the child's emerging ability to comply with a request, to inhibit or delay an activity, and to monitor behavior according to the situational demands
OCR for page 118
From Neurons to Neighborhoods: The Science of Early Childhood Development (Kopp, 1982). The ability to exercise self-control increases from 18 to 30 months and becomes more stable across time and across situations (Vaughn et al., 1984). The capacity to use developing executive function to regulate behavior and emotions in the service of social goals and situational demands is sometimes referred to as inhibitory or effortful control, as discussed above. Because many skills, competencies, and experiences affect whether a child can regulate his or her emotions and behavior, researchers have used a wide variety of tasks to assess individual differences in effortful control. These tasks include being able to shift with ease from doing something as “fast as you can” to “as slow as you can” to being able to “not peek” when waiting for a surprise gift, to being able to play games like Simons Says. When individual differences on such tasks are assessed and averaged, they provide one window into why some children comply more readily with adult requests not to touch interesting things even when the parent is not watching and more readily resist the temptation to cheat on games even when they think they will not be caught. Being good at effortful control tasks, including those that more directly assess executive functioning, doesn't mean that a child will behave in compliance with social rules that require self-control, however. Aspects of children's relations with others that motivate them to want to adopt the rules of their group also matter (Kochanska, 1990). A number of researchers have investigated the developmental trajectories of executive function by presenting children with a battery of tests purported to measure different aspects of this domain of regulatory behavior (e.g., Gnys and Willis, 1991; Levin et al., 1991; Welsh et al., 1991). The focus here is not on precursors of executive function, but on manifestations of behaviors that constitute components of this construct. These studies have demonstrated that the different component skills involved in executive functioning show different developmental trajectories and mature at different rates. In one of the first studies to include preschoolers, children ages 3 to 12 were presented with a series of tasks that involved visual searching, verbal fluency, motor planning, planning sequences, the ability to respond flexibly to changes in the environment, and the capacity to inhibit responses (Welsh et al., 1991). Patterns of performance on these measures indicated that three underlying factors captured children's responses: (1) fluid and speeded response (2) hypothesis testing and impulse control and (3) planning. The investigators interpreted their findings as evidence for stage-like development, with the first stage beginning around age 6, the next stage around age 10, and the final stage during adolescence. Six-year-olds, for example, were able to perform as well as adults on tasks that involved visual searching and planning simple sequences, whereas it was not until adolescence that the ability to plan complex sequences, verbal fluency, and motor planning reached maturity.
OCR for page 119
From Neurons to Neighborhoods: The Science of Early Childhood Development In contrast to the research on children's emerging capacities to regulate states and emotions, relatively little is known about how parents, other adults, and features of children's early environments affect the development of attention regulation and emerging executive functions. These influences clearly matter (Carlson et al., 1995), but researchers have yet to identify the mechanisms that account for individual differences among young children. Research on school-age children demonstrating that it is possible to teach attentional skills and executive functions to individuals with developmental disabilities (Borkowski and Burke, 1996; Graham and Harris, 1996) also indicates that they are amenable to environmental influence. Deficits in Executive Function and Attention The importance of understanding how children learn to plan and organize new actions, remember past experiences and bring them to bear on new experiences, and maintain attention to tasks is underscored by the consistent relation of deficits in any one of these processes to problems in school (Lyon, 1996). Of great interest to educators and parents alike is growing evidence that deficits in attention regulation and behavioral control are integral to disorders such as attention deficit hyperactivity disorder (ADHD). They also have vast implications for social and emotional behavior given the highly permeable boundaries between cognitive abilities and social competence. For example, forethought and planning are intimately involved in making friends, seeking attention, and solving interpersonal conflicts. Because social interactions involve people and people are often unpredictable and have their own goals that may interfere with one's own, flexibility is essential for achieving social goals (Goodnow, 1987). To be a competent social problem solver, one must be able to detect obstacles that will interfere with social goals, generate and evaluate alternative strategies to overcome or prevent these obstacles, and be able to flexibly adapt behavior to meet the challenges presented by the constantly changing social environment (Rubin and Krasnor, 1986). These are extremely challenging tasks for young children. Designing appropriate, individualized interventions for young children who are displaying early deficits in organizational, planning, and attention-related capacities depends on understanding the processes that underlie their development and manifestation. Taking ADHD as an example, this is generally considered to be a relatively common disorder, with prevalence estimates ranging from 0 to 16.7 percent with a median of 2 percent for school-age children (Lahey et al., 1999). Yet the true prevalence and the cause of ADHD remain unknown (Zametkin and Ernst, 1999). According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV; American Psychiatric Association, 1994), the diagnosis of ADHD requires
OCR for page 120
From Neurons to Neighborhoods: The Science of Early Childhood Development evidence of either inattention or hyperactivity and impulsivity. There are three subtypes of ADHD, the predominantly hyperactive-impulsive type, the predominantly inattentive type, and the combined type. Most of the research to date is on the hyperactive-impulsive and combined types. Focus on the inattentive subtype is an emerging research topic. Tests of the validity of the three DSM-IV subtests of AHDH for preschoolers have been conducted with children 4 to 6 years of age. The findings show that the subtests are valid for children of these ages (Lahey et al., 1998). Yet diagnosis is complicated by the fact that many of the behaviors associated with ADHD are normal for preschoolers who often have difficulty paying attention and are impulsive and fidgety by nature. And there is no information about the validity of ADHD diagnosis below age 4. The absence of a nationally representative epidemiological study of mental health problems in the childhood population leaves us in the dark with regard to efforts to distinguish children who are at the ends of a typical spectrum from those who are manifesting serious delays. A related critical issue in both research and practice concerns how to differentiate ADHD from other frequently coexisting conditions, such as learning disabilities, oppositional-defiant disorder, conduct disorders, and anxiety disorders and also how to individualize treatment when ADHD occurs in conjunction with these and other disorders. A recent study of 7- to 9-year-old children shows that different types of treatments for ADHD benefit individuals with different combinations of problems (MTA Cooperative Group, 1999). Finally, recalling the core concepts in Chapter 1, it is critically important to note that many of the symptoms of ADHD are also nonspecific indicators that something is not quite right. Heightened activity can also occur, for example, when a child is overly tired or upset. This can make the clinician's task of sorting out true disorder from other problems exceedingly difficult, perhaps especially with a diffusely defined disorder such as ADHD (Rutter and Sroufe, in press). In sum, understanding the constructs of attention, memory, and executive function is critical for understanding how children think, learn, and develop. Because these constructs are hard to define and have overlapping boundaries, there is a pressing need to develop more refined definitions of executive function and its component skills, and for valid measures of early manifestations of pertinent behaviors and abilities (Weinberg et al., 1996). The capacity to map specific executive functions onto specific areas of the brain and to distinguish normal development from emerging disorders is dependent on such efforts to lend greater precision to the analysis of task demands and individual children's responses. For these important capacities, there is much to learn about the emergence, integration, and consolidation of the skills that serve as building blocks for adaptive behavior and
OCR for page 121
From Neurons to Neighborhoods: The Science of Early Childhood Development provide a yardstick against which to evaluate what is abnormal neurological or cognitive development. It is clear at this point that the various components of active, internally guided regulation of attention, behavior, and emotion emerge in intricately interrelated ways at the end of the first year of life and then develop more rapidly during the toddler and preschool years (Kopp, 1982; Rothbart and Bates, 1998). They emerge in the context of caregiving relationships that explicitly guide the child from her dependence on adults to regulate virtually every aspect of functioning to gradually taking over and self-regulating her own behaviors and feelings in one aspect of her life after another. Parents don't tell their 3-year-olds to clean up their rooms and then leave them to their own devices. They help by suggesting that they start with the clothes and throw them in the hamper and then put away their blocks on the shelf. They praise them at each step along the way and then move on to pulling the covers up on the bed. They repeat these patterns over and over, day after day, and then begin to pull back the scaffolding as the child begins to do it himself. Some children need more scaffolding than others and for longer times. Some children have serious disorders, such as mental retardation, that interfere with their ability to benefit from parents' and others' efforts to help them practice and then extend their emerging competencies. Sorting out children who don't have sufficient help from those with serious disorders is extremely challenging. In attempting to distinguish normal development from emerging disorders in these regulatory domains, it is crucially important to consider the contexts within which children's executive functioning and self-regulatory behaviors have been struggling to develop. SUMMARY AND CONCLUSIONS The capacity for self-regulation, ranging from sleeping and settling in the earliest weeks of life to the preschooler's emerging capacity to manage emotions, inhibit behavior, and focus attention on important tasks, reflects young children's transition from helplessness to competence. Stated simply, early development entails the gradual transition from extreme dependence on others to manage the world for us to acquiring the competencies needed to manage the world for oneself. Research on this transition has focused on the triad of regulatory tasks captured by emotion regulation, behavior regulation, and attention regulation. In reality, however, these dimensions of self-regulation are highly interrelated. Success in one area can fuel success in another; problems in one area can undermine development in another. There is much to learn about normative patterns of regulatory development, as well as the adjustments made by young children
OCR for page 122
From Neurons to Neighborhoods: The Science of Early Childhood Development with a range of developmental disabilities, and the mechanisms that under-lie the successful navigation of the many challenges encountered en route to well-regulated behavior. Regulation in early development is deeply embedded in the child's relations with others. Providing the experiences, supports, and encouragement that enable children to take over and self-regulate in one area of functioning after another is one of the most critical elements of good caregiving. Indeed, the locus of regulatory problems during the early months of life is increasingly seen as residing not in the infant's behavior (e.g., excessive crying, irregular sleeping) but in the transactions that transpire between infants and their caregivers and the more enduring perceptions and patterns of interaction that are subsequently set in motion in the family. These transactions, in turn, provide a promising entry point for early interventions aimed at getting new parents and their infants off to a good start. There is also growing appreciation of the fact that learning to regulate one's emotions, behaviors, and task-oriented capacities is a different challenge for children with different temperaments, for children with a variety of diagnosed disabilities, and for their caregivers. While overly active and disinhibited children often come to the attention of adults, those who fall at the other end of the spectrum all too often are overlooked. Recent attention to problematic regulatory behavior has, in fact, been prompted by growing concern about early precursors of conduct problems, attention deficits, depressive and anxiety disorders, and other psychological problems of childhood. While emerging evidence suggests that regulatory problems can offer early warning signs, there are many pitfalls on the road to early diagnosis. Virtually all young children display “poorly regulated” behavior simply as part of being a little kid. Children with temperaments that give them more to regulate can appear to be deficient in self-regulatory abilities when, in fact, they are not. In this context, identifying and intervening with children who need extra help is fraught with ambiguity and runs the risk of overdiagnosis and unnecessary treatment. Nevertheless, some young children are struggling with serious mental health problems and need help urgently. These issues were highlighted recently by the Surgeon General's report on mental health (U.S. Department of Health and Human Services, 1999b), which includes an extensive discussion of children's vulnerability to mental health problems, the importance of understanding these problems in the context of children's social environments, and the nation's serious personnel shortages that constrain the capacity to address them. Recent reports of extensive use of pharmacological treatments for preschoolers with behavioral disorders (Zito et al., 2000) have raised urgent questions about how best to address social and emotional problems in young children and further highlight how poorly
OCR for page 123
From Neurons to Neighborhoods: The Science of Early Childhood Development equipped the nation is to respond to these issues. For children whose problems do not fall within the clinical range, early interventions to address regulatory behavior focused on “fixing” the environment to reduce demands on the child warrant serious attention to balance the current focus on “fixing” the child. It is also clear that focusing on young children 's relationships with adults and peers is a promising and complementary, yet poorly exploited, approach. Finally, cultural dimensions of regulatory development have been neglected by most scientists and practitioners alike. Nevertheless, cultural values have a profound impact on how young children learn to interpret and express their emotions, and on the behaviors that are seen as appropriate in different circumstances. Cultural expectations about self-regulatory behavior can even affect the boundaries of what is considered “childhood.” The Yoruba, for example, define childhood in terms of self-reliance and no longer refer to children who can talk, walk, dress themselves, and do certain other things around the house as children (Zeitlin, 1996). These cultural dimensions have important yet unexplored implications for children whose home culture is not the same as the dominant culture in other settings they inhabit (e.g., child care, homes of friends, intervention programs) and for adults who work with diverse groups of young children and whose responses to their behaviors are highly contingent on their own cultural expectations.
Representative terms from entire chapter: