[Introduction]
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[III. We Know What Works]
Across the nation, nearly 4 million babies are born each year. Each enters the world with immense promise. Each arrives with billions of brain cells just waiting to have their power unlocked. Many of these cells have already begun to link up to one another, but a newborn?s brain has yet to form the roughly 100 trillion connections that make up an adult?s complex neural networks. For these connections to form and proliferate, cells need a crucial ingredient: experience in the world. From the very first days of life, brain cells connect at an astonishing pace. Young brains forge more than enough connections in the first 3 years of life; as children move toward adulthood, these connections are pruned and fine-tuned. This is good news for humans. It means that our newborns? capacities—their unique ways of thinking, knowing, and acting—develop in the world, under the sway of the adults who love them and nurture them.
The impact of early experience on early brain development is powerful and specific, and may last a lifetime. This is a major finding of recent brain research, and it represents a sharp departure from centuries-old ideas about how children develop and grow. Its implications can be summarized in 10 key lessons that emerged from the conference.
Only in recent decades have scientists fully appreciated the significance of early experience. For most of our history, it was assumed that newborns? brains were largely pre-programmed, and that development consisted in the gradual unfolding of innate abilities and tendencies. Today we base educational policy on the oft-repeated premise that virtually every child can learn to high standards. This hardly sounds like a revolutionary stance, but in the history of education, it is a novel and bold concept. For generations, it was widely believed that based on inborn traits, some children could be expected to become able learners and productive workers, while others were destined to dimmer futures. Experience and education were considered helpful, but could hardly be expected to overcome nature?s preset limits. Americans continue to hold onto this conviction.
New scientific evidence turns this assumption on its head. Heredity certainly plays a role, and geneticists are learning more each day about how genes affect development. But as each child grows and matures, early experience exerts a powerful force, sculpting the genetic "clay."
Today, most experts agree that early development is a complex dance between nature and nurture. Some researchers are producing new evidence that in the early years, nurture leads that dance; one recent study suggests that in infancy and childhood, the impact of experience on cognitive ability is significantly more powerful than the influence of heredity. 1. The relative importance of experience appears to decrease as individuals move through the life cycle. This finding is sure to be debated in coming years; but whatever the ultimate conclusion, scientists now underscore the importance of early experience, the power of effort, and the hope of education.
It is natural to think of babies as ourselves in miniature—adults on a smaller scale. But the more we discover about young brains, the clearer it becomes that young children differ from adults in important ways. They have unique ways of developing, learning, and responding to the world around them. By taking these differences into account, parents and professionals can do a better job of meeting young children?s needs.
At birth, children?s brains are in a surprisingly unfinished state. Newborns have all of the genetic coding required to guide their brain development. What?s more, they have nearly all of the billions of brain cells, or neurons, they will need for a lifetime of thinking, communicating, and learning. But these neurons are not yet linked up into the networks needed for complex functioning. It is like having billions of telephones installed around the nation, but not yet completely connected to each other.
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Phoning Home You might think of a brain cell as something like a telephone—although unlike a phone, it communicates with other brain cells by a combination of chemical and electrical signaling. Now, like a phone, each brain cell connects with other brain cells—anywhere from 1 to 10 thousand of them. So when you make a connection, 1 phone may ring, or 10 thousand may ring. In all, the brain has to create a network of more than a hundred trillion connections; what?s more, the hook-ups have to be very precise so that when you phone home, you reach your house and not a wrong number. This is a daunting task considering that at the outset, nothing is connected to anything else in the brain. It takes a two-step process. First, you need trunk lines—the gross wiring. You have to string telephone wires from one city to another, so when you place a call from Kansas City to Washington, DC, you don?t reach San Diego. In terms of brain development, this means that the neural connections from the eye have to grow to the visual part of the brain. Connections from the ear have to grow to the auditory part of the brain. And so on. But the problem of wiring isn?t over. Once the trunk lines are in place, you still have to make sure that your call goes to the right address in Washington, DC, so when your grandmother calls you up in Washington, DC, your phone rings and not the phone at the White House. This is not a trivial problem. Let?s take the connections from the eye to the brain. There are about a million connections from each eye, and there are about 2 million possible destinations that each one of these connections could reach. And yet fewer than 100 connections are selected from this vast number of addresses—and that?s just the visual system. So what is the solution? One possibility is that the brain could be wired like a computer. You could build the machine, program all of the connections, push a button, and pray that the right phone rings in the right city. In other words, the brain could rely on genetic coding for the entire process. But imagine how much coding it would take to program trillions of connections. Nature?s solution is much more adaptive and economical. In the process of development, the gross wiring is pre-programmed primarily by means of genetic coding. And then midway through the process, before all the wiring is complete, it?s as if a switch is flipped and the newly functioning brain takes over the wiring process. In this way, wiring the brain is a two-phase process. In the first phase, an infant?s brain sends signals in the right general direction. It reaches the right city; but when it tries to phone home, there is ringing all over town. But then, in the second phase, the brain takes over. It places trillions of phone calls, using them to correct initial errors in address selection. In a sense, the brain is running test patterns to figure out which are the most efficient connections. The wrong numbers are eliminated, and the right ones are reinforced and proliferate like mad. So the baby?s brain is not just a miniature version of an adult brain. It is a dynamic evolving structure that uses experience to form efficient neural networks. Adapted from the presentation of Dr. Carla Schatz |
The extreme immaturity of the newborn?s brain is uniquely human. We tend to take it for granted, but not every species gives birth to such undeveloped infants. At birth, the human brain is only a quarter of its adult weight; the newborn brains of other primates are already 40 or 50 percent of their adult weight. The young of other species are rarely as helpless as newborn humans, and don?t take as long to move toward independence.
This may sound worrisome, but in fact, our initial immaturity gives humans a powerful evolutionary edge. Monkeys, mice, and minnows are limited in the kinds of settings in which they can survive. Humans have found ways to adapt to almost any habitat on earth. Why? In large part, because so much of our brain development takes place in the world—in contact with our environment. That crucial fact means that experience plays a far greater role in the wiring of our brains. Our developing nervous systems can be significantly altered and fine-tuned by experience. This makes humans uniquely flexible and adaptable. It also allows us to have far greater individuality than other species.2 Different people?s brains—even those of identical twins—will be wired differently based on their responses to different activities and stimuli.
A young child?s brain is a work in progress, and scientists are now able to watch it unfold. Thanks to new, computer-based imaging technologies, such as ultrasound, MRI, and PET scans, they can now see the brain?s structures in greater detail than ever before. They can get a glimpse of how the brain responds to different experiences and how it uses energy. They can see how the brain looks and functions at different stages of development, including in the months before birth.
Crucial steps in brain development take place early in pregnancy, before many women know that they are expecting. Within weeks of conception, cells that are destined to become neurons have to find their way to the correct position in the part of the brain most responsible for reasoning and learning. For brain development to proceed normally, each cell has to make its journey at the right time, in the right order. Nature has powerful mechanisms to guide the process, including genetic coding, and expectant parents can rest assured that in the vast majority of cases, development proceeds just as it should. But even in the womb, the brain is vulnerable to environmental influences. When pregnant women have inadequate nourishment, when they smoke, drink, or take drugs, or are exposed to toxic substances, their babies? brain development may be jeopardized. Research also suggests that when women suffer abuse, extreme stress, or severe depression, their babies may be affected.
Newborns have more awareness of the world than most of us realize. On the first day of life, a newborn can look at his surroundings, study objects, and gaze in the eyes of his mother or father. Infants as young as 2 days of age will sometimes suck at the mere sight of a breast or bottle, suggesting that learning takes place from a child?s earliest hours of life.3 But the process of getting to know the world is just beginning. At birth, a newborn cannot yet make sense of the flood of sensation and information that comes his way.
As new experiences arrive, young children?s brains respond by forming and reinforcing trillions of connections, or synapses, among neurons. In the time that it takes for mom to nurse the baby or for grandpa to read Goodnight Moon, thousands of new synapses are produced. At the same time, thousands of existing synapses are used or "fired" and, in the process, reinforced.
Connections form so quickly that by the time children are three, their brains have twice as many synapses as they will need as adults. These trillions of synapses are competing for space in a brain that is still far from its adult size. According to Rethinking the Brain, a report by the Families and Work, by the age of three a young child?s brain is apt to be more than twice as active as that of her pediatrician.4 Children are biologically primed for learning, and the first 3 years are particularly crucial.
If children have more synapses than they will have as adults, what happens to the trillions of excess connections? The answer is they are shed as children grow. Scientists report that throughout the development process, the brain is producing new synapses, strengthening existing ones, and getting rid of synapses that aren?t used often enough. Before the age of 3, synapse production is by far the dominant process; from 3 to 10, the processes are relatively balanced, so the number of synapses stays about the same. But as children near adolescence, the balance shifts, and the shedding of excess neurons moves into high gear.
Brains downsize for the same reasons so many other "organizations" do: with streamlined networks, they can function more efficiently. But how does the brain "decide" which connections to shed and which to keep? Here again, early experience plays a decisive role. Each time synapses fire, beginning with the early months and years of life, they get sturdier and more resilient. Those that are used often enough tend to survive; those that are not used often enough are history. In this way, a child?s experiences in the first years of life affect her brain?s permanent circuitry.
Because experience in the world so powerfully affects early development, no two brains grow and mature in the same way. Children are individuals right from the start, even if they are raised in the same culture, locality, or even household. Even the brains of identical twins develop differently, based on their early surroundings and interactions with the adults who care for them.
As anyone who has ever raised a child can attest, no parent can completely plan or predict how a son or daughter will grow and develop. The settings and experiences that parents provide are crucial, but many other factors are also at work, and parents cannot regulate (or take responsibility for) every aspect of their children?s development. Newborns arrive with different temperaments, strengths, and needs. Many children are born with abilities or disabilities that present them and their families with special challenges. Some boys and girls encounter difficulty despite their families? love and commitment; others show remarkable resilience, growing into hearty children and able learners despite circumstances that overwhelm other young people. While the researchers attending the White House Conference were eager to explain the importance of early experience, none would argue for replacing the notion of genetic "programming" with experiential "programming." The new brain research answers many questions about how children grow and develop, but it does not diminish the reality that every life is unique and complex.
In the first years of life, parents have considerable (though not complete) control over the kinds of experiences their children are exposed to. But what kind of experiences do infants and toddlers need? Researchers are finding that, more than anything else, young children need secure attachments to the adults who care for them.
Newborns discover very quickly that they are not alone. From birth, they are capable of observing and interacting with other people. Babies grasp that the world we?ve brought them into is a fascinating place. When they are awake and alert, they lose no time exploring their surroundings with all of their senses. But nothing is more interesting or important to them than their mothers and fathers. Very early in life, babies turn most eagerly toward the voices of the people they know best.
Children are dependent to a greater extent and for a longer stretch of time than the young of other species are. They are also trusting. They turn to parents and other caregivers for reassurance or help. They believe that these adults will nurture and protect them, unless repeated experience teaches them otherwise.
They know that interacting with parents and other important people—communicating, mimicking, playing, snuggling—is the best way to spend their most alert, wakeful hours. Babies respond to touch, sound, images, tastes, and smells. They are at ease when they receive warm, responsive care geared to their needs, moods, and temperament. When this kind of care comes consistently from the same adult or adults, young children form secure attachments. They sense that they are loved and protected even during quiet or sleepy times, and while at play by themselves.
When children form secure attachments, their development tends to flourish. Long-term studies show that children who have secure attachments early in life make better social adjustments as they grow up, and do better in school.5 But when care is inadequate, mechanical, or inconsistent, young children experience tension, and research shows that this stress affects their heart rate, brain waves, and their brains? biochemistry. A major finding of recent research is that chronic stress can have an adverse impact on the brain, and can result in developmental delays.6 This finding is borne out by studies of young children who are subjected to extreme social and emotional deprivation over extended periods.
Some parents are understandably unsettled by research showing that the way they relate to their young sons and daughters, and the experiences they provide or arrange, help to determine how their children?s brains will be wired. They may wonder: Did I pay enough attention to Jake and Mary when they were babies? How many connections formed, or failed to form, during the 10 minutes Emily was left to cry so Robert?s bee sting could be tended to? What about all the times the neighbor lost his temper and shouted at Rebecca? Has musical potential been wiped from Melissa?s brain because we never played Mozart or Bach?
But when you look at life from a baby?s viewpoint, you realize that you don?t have to be a perfect parent. What matters to young children is your ability to understand their needs and to read their signals most of the time; to respond with warmth and affection, to model the pleasures of conversation and turn-taking, to protect them from life?s minor bumps and bruises as often as possible, and to shield them from neglect and abuse.
Social experience has a greater impact on brain development—including children?s emerging intellectual capacities—than many scientists had realized. As obvious as this is to many mothers and fathers, a survey conducted by Zero to Three, released at the White House Conference, showed that fully a quarter of parents do not believe this. The research is clear, however. Children learn in the context of important relationships: interactions with parents, grandparents, brothers and sisters, and other family members.
Fathers have a critical role to play. Research showed that the attachment a child forms with his or her father is critical to that child?s development. When fathers are active caregivers, their children tend to do better on cognitive tests and are less prone to violence. Of course, these results hinge on the quality of the relationship a father establishes with his young children, as well as the amount of time he devotes to caring for them.
Traditional roles are changing slowly in most families. Research in the early 1980s reported that fathers, on the average, spent less than half an hour per day directly interacting with their children. More recent studies are showing that many men have somewhat increased the time they spend interacting with their children and taking care of them.7 But many fathers say that they meet obstacles when they try to become more involved. Some say that they would spend more time with their sons and daughters if they met less resistance from the children?s mothers, or if their employers adopted more family-friendly policies.
Mothers and fathers have a strong stake in the well being of the children they bring into the world, but biology is not the chief factor in good parenthood. We know that adoptive parents can have a large, sustained impact on children?s development. So can foster parents and grandparents. So can childcare providers who are steady presence in children?s lives. And so can family, friends and neighbors. Again, while opportunities are especially strong in the early years, important relationships make a difference for children at any age.
Research shows that children are capable of forming strong attachments to more than one adult, but not all attachments are equally strong or compelling. Babies tend to prefer their primary caregiver—usually mom. But they quickly learn that other people can meet their needs, and that different people—dad, Uncle Mike, grandma, or Ms. Cutler—have different ways of caring for them. In this way, they begin to get a sense of life?s complexity and richness.
Childcare providers can be important people in young children?s lives, but they do not take the place of parents. Recent studies show that high quality childcare does not disrupt young children?s attachments to their parents—so long as parents spend enough time with their infants and toddlers to know them well, care for them confidently, and read their signals and cues.
Childcare and the FamilyJust as research on the inner workings of the brain has ironically directed attention outward to the importance of the environment, research on childcare has affirmed the centrality and durability of the family in the development in young children. Today, the vast majority of families are sharing the rearing of their children with childcare providers, starting in the very first few weeks of life. We know from the new national study of infant childcare funded by the National Institute of Child Health and Human Development that 80 percent of infants in the United States experience some regular nonmaternal childcare during the first 12 months of life. Most of these babies started childcare before their 4-month birthday; they are in care typically for close to 30 hours a week. We are talking about a very high "dosage" of early childcare for most U. S. babies. The good news is that, according to research, young children—including babies—can thrive in childcare when it is of high enough quality. In fact, by placing your children in high quality childcare, you can actually supplement what you are giving them at home. That is why the importance of making high quality childcare affordable for more families cannot be undervalued. Moreover, placing a baby in childcare does not interfere with the development of the mother-infant attachment relationship or the father-infant attachment relationship. So long as parents spend enough time with their babies to become confident caregivers and understand their needs, their bonds with their children will be extremely resilient. No matter when families first start childcare, no matter how much childcare they use, the family remains by far the most powerful influence on their children?s development. The bad news is that most of the settings where American children receive out-of-home care fall short of any standard that could be considered optimal. "Barely adequate" has become the term of art to describe the typical childcare arrangement in this country. Virtually every study that has involved actually going inside childcare settings and observing what happens has found that about 15 to 20 percent—one out of every five or six programs—are in fact dismal and even dangerous. And those are the settings that will let us in to observe them! Infants seem to get the poorest quality of all. Of course, we also see fabulous childcare in all kinds of arrangements, whether it is from grandma or a teacher in a childcare setting. Neuroscience tells us that these suboptimal childcare environments should affect early development. Childcare research confirms that they do. The quality of the childcare environment significantly affects virtually every aspect of development that we know how to measure, whether it is problem-solving skills or social interactions or attention span or verbal development. The key to raising quality lies with the caregiver. Good care giving looks a lot like good mothering and good fathering. Children show significantly better cognitive and language skills, as well as social and emotional development, when they are cared for by adults who engage with them in frequent, affectionate, responsive interactions, who are attentive and know how to read a baby?s signals and respond to the baby?s temperament. We know how to provide high-quality childcare. The unified efforts of the four branches of the military have proven this, as has Head Start. We need to improve adult-to-child ratios; expand training and create career ladders for caregivers; reduce staff turnover by improving pay and benefits; and strengthen parent involvement. Adapted from the presentation by Dr. Deborah Phillips |
In fact, childcare providers—with sufficient training and support—can enhance the development of the children in their care, supplementing the parents? input. Children benefit when parents and childcare providers work together, exchanging information, insights, and problem-solving strategies on a regular basis.
Many aspects of children?s environments affect early brain development, from the sights to sounds to textures that surround them. But recently scientists have been homing in on linguistic experience as a key ingredient. More precisely, they are stressing the importance of "small talk"—the millions of ordinary greetings, exclamations, explanations, complaints, and utterances exchanged between adults and children in the course of the early years.
Over the last quarter century, scientists have learned a great deal about how children acquire language. Parents have long suspected that babies? babbling is basic training for speech, and that their gestures and cries eventually evolve into more sophisticated forms of communication. But new research shows that infants make more rapid progress in cracking the language code than we previously thought. From their early months, they pay close attention to the language they hear. 8 By the time they reach their first birthdays, they are well on their way to mapping the sound structure of language—or, in multilingual homes, to the language they hear most consistently.
Citizens of the WorldOver the past 25 years, we?ve learned a tremendous amount about the child?s acquisition of language. The new research shows that in the first year of life, infants are mapping the sound structure of language. In fact, by 6 months of age, they are well on their way to cracking the language code. It takes both nature and nurture—or, to say it another way, both biology and culture—to bring this about. Newborns are very well prepared to acquire language. At birth, infants across the world can discriminate all of the sound contrasts that are used in any language of the world. I like to refer to them as citizens of the world. They don?t know which language they are going to have to acquire, so they are prepared for anything. This is quite a feat because the acoustic events they have to pay attention to are very, very minute. Over time, infants have to change from citizens of the world to culture-bound language specialists. There is now evidence that by 12 months of age, they are well on their way to mapping the sound structure of their particular language. We know this because we have been doing studies in all over the world, observing babies as they listen to different languages. In Stockholm and Seattle, for example, we observed that by 6 months of age, babies are already focusing on the particular language sounds that their language uses contrastively, rather than the sounds of all languages. We have just learned, from studies in Japan, that infants who at 6 months of age were able to hear the distinction between R and L no longer do so at 12 months. In other words, by the time they reach their first birthdays, babies have begun to ignore the variations that are not essential to their language and to pay attention only to that set of sounds that are critical for distinguishing words in their particular language. What this research shows is that by 6 months of age, infants? perceptual systems have been altered simply by listening to us speech. Now, 6 months are very little babies. They have yet to produce a single word; the have yet to understand a single word, and yet the lesson from the research is that they are listening to us speak and their brains are busy coding the sound structure of the language they are going to have to master in order to be able to talk back. So the language we produce to infants is vital to them, and that puts a great deal of responsibility on us. Adapted from the presentation by Dr. Patricia Kuhl |
Adults have special ways of talking to children that help them analyze language. Intuitively, they speak more rhythmically, slowing down their speech, exaggerating phonetic shifts, and simplifying their vocabulary and grammar. Speakers of "parentese" often set their words to enticing melodies that act as acoustic hooks, pulling the baby?s attention to them. This kind of talk lets babies know that they are being addressed; punctuated by pauses, it helps young children learn that relating to others is about taking turns. Many kinds of early interactions—a game of peekaboo or mimicry of a baby?s faces—can lay the groundwork for effective communication later in life.
But some parents do not realize the importance of talking to their children in the first year before their children are old enough to begin talking back. They may feel self-conscious when they talk to an infant who cannot respond; or they may have few positive models of conversation between parents and young children. In other cases, parents may be too tired or stressed to engage in lighthearted chitchat with their babies. It is easy to empathize with these mothers and fathers, but research suggests that their children may be missing out on important learning opportunities.
How can researchers gauge the impact of early interchanges? A common-sense approach is to observe numerous infants, record their interactions with their parents or caregivers, and then follow each child?s progress over several years to see how he or she develops and fares in school. One recent study found that a child?s earliest language experiences do indeed affect later achievement. For a period of 2 1/2 years, beginning with birth, the researchers spent an hour each month documenting every spoken word and every parent-child interaction in each of 42 homes. They found that the more parents talked to and interacted with their babies, the greater the children?s chances for success when they reached elementary school. They concluded that both the number of words exchanged and the tone in which they were said made a difference. All of the children in the study learned to use language and construct complex sentences, but the children who were talked to at a younger age had a stronger grasp of the conceptual possibilities of language, and became better problem solvers.9
Linguistic experience constitutes an important part of the setting in which young children grow up, and can have a positive or negative effect on children?s development. Very young children who may not make sense of words nevertheless respond to tone. Language that is soothing, novel, or buoyant can spark their curiosity and help them feel secure and engaged in family life. At the same time, cascades of negative comments or commands can certainly provoke stress, even when the words are not directed at the children, and even when infants or toddlers are too young to fathom their meaning.
Once parents know about this kind of research, most will want to make "small talk" with their infants more frequent, warm, and responsive, and they will want to be sure that childcare providers are talking with their babies as well. The prospect of keeping up a steady flow of conversation may sound exhausting, but babies appear to benefit from exactly the kinds of commentary that run through parents? and caregivers? minds as they move through their day. In the study mentioned above, the patter that went on between the chatty parents and their infants was not about Buddhism or Beethoven—or, for that matter, brain science. You need not discuss complex ideas to help your infant learn. But a stream of statements like, "Your cereal is almost ready," or "Daddy is looking for his keys," appears to help babies become more conceptual thinkers later in life. Simple questions like, "How was your nap?" or "What did we do today?" can make a world of difference.
Children need chances to stretch not only their linguistic and conceptual abilities, but also their powers of perception, social prowess, and aesthetic and moral capacities. And of course, all children need physical exercise. When children are severely deprived of experience in any of these areas, their development may be delayed. For example, babies and toddlers who spend most of their waking hours in their cribs develop more slowly than other young children do; some cannot sit up at 21 months, and most cannot walk by age 3.10 Children need opportunities for vigorous, safe physical activity. They need touch, sounds, and images. They need social and emotional contact. And they need thought-provoking activities. Most adults who care for children have some awareness of these needs. But despite parents? best intentions, many infants and toddlers do not get enough intellectual stimulation. This was a major finding of Starting Points, a Carnegie Corporation report on meeting the needs of young children that was cited at the White House Conference.11 Starting Points reported that only half of infants and toddlers are routinely read to by their parents.
On the other hand, too much stimulation can be overwhelming. Young children have different temperaments and moods. They also have different daily cycles of wakefulness and sleepiness than adults. Their capacity to respond to different kinds and amounts of stimulation can fluctuate from hour to hour, or even from minute to minute. Aside from seeing to their children?s basic health and safety, the most important thing parents can do is to learn to read their children?s moods and preferences and, whenever possible, adjust activities, schedules, and even the way they touch and talk to their young children.
With practice, many mothers and fathers become quite adept at reading their children?s cues and signals and anticipating their needs. But like so many aspects of parenting, this is easier said than done. Children can be volatile and unpredictable. From birth, children appear to
have different temperamental characteristics. Research suggests that most infants and toddlers have traits that make them "easy" children; but a significant number—about 10 percent—have difficult temperaments. They tend to be moody, express intense emotion, and resist efforts to comfort them or cheer them up.12
Furthermore, some children are born with, or develop, disabilities or illnesses that may impede their ability to form strong relationships and to respond to different kinds of stimulation—severe retardation, autism, or mental illness, for example. Others may have learning disabilities that do not fully respond to current treatment methods. Research points to new ways to help every child reach his or her full capacities. Working with professionals, parents can acquire the information and strategies they need to support their sons and daughters as they gain new skills and new confidence. New ways of approaching disabilities like mental retardation or autism are helping to improve conditions that were once considered untreatable. But some children will continue to have difficulties no matter how much love, care, attention, and stimulation their mothers and fathers provide.
The brain does not develop all at once. Different parts of this complicated organ mature at different times and at different rates.13 Although development continues throughout life, there are periods of great opportunity (and risk) when a particular part of the brain is the site of intensive wiring and is therefore especially flexible. These are known as critical periods.14
The classic example is vision. The visual part of the brain is wired early in life, but this doesn?t happen automatically. The necessary connections do not form until the brain receives the specific stimulation it needs, in the form of visual experience. Timing is crucial. If the brain does not receive this stimulation on time—before the critical period for vision has passed—the required connections will never form and the part of the brain that controls vision will not fully develop.15 That is why time is of the essence when cataracts cloud or block a baby?s vision. Surgery must be performed in a timely way, or the baby may lose her sight permanently. But if this baby?s grandfather develops cataracts, the situation is very different. Because grandpa long ago received the visual stimulation his brain needed for normal development, cataract surgery can restore his sight even after a long delay.
The concept of "critical periods" helps to explain why the early years are so important, and why it can be hard for parents and teachers to compensate for experiences that were missed in the first years of life. During these years, responsive care and appropriate stimulation can produce the rapid intellectual, social, and emotional growth that does not usually come as easily to older children. In most cases, there is plenty of time for children to get the stimulation they need. Critical periods generally are not as narrow for cognitive and social growth as they are for vision. The window of opportunity for efficient language development, for example, can stretch for more than a decade.16
At the same time, the early years are also filled with risk. Untreated health problems, poor nutrition, exposure to tobacco, alcohol, drugs, or environmental toxins, and abuse and neglect are always risky, but may be especially perilous in the first years of life.17 Traumatic experiences and nonstop stress are also particularly harmful early in life; they affect production of a steroid hormone called cortisol that can have an adverse impact on brain development.18 Maternal depression is another factor that can affect early development. Many new mothers experience postpartum blues for a few weeks or months; this is normal and unlikely to have a lasting impact on her baby. But research shows that if a mother?s depression persists, a young child?s brain activity may be affected. The good news is that when the depression lifts or is treated, the child?s development can usually get right back on track.19
The bottom line is that in the early years of life, prevention and early intervention are crucial. When health problems are addressed, when family stress is reduced, when mothers seek treatment for depression, young children tend to fare better. The earlier the intervention, the better. The more follow-up, the better. These are simple lessons. As they are applied more widely, results for young children are bound to improve.
Unconditional love goes to the heart of what it means to be a parent. But love is not enough. From a child?s viewpoint, good care is responsive care. It requires getting to know a particular child very well, and that is not simply a matter of instinct or affection; it usually takes time and practice and help from more experienced caregivers. Parents and caregivers don?t always get it right the first time, or even the second, but if they are willing to follow the children and learn from their mistakes, they come to understand the needs and temperaments of their children.20
Mistakes are inevitable. As the lullaby promises, the cradle will rock. A baby who is full will be coaxed to eat. A toddler will be tossed into the air by an enthusiastic dad when what he really needs is a cuddle and a nap. And parents will frequently realize, after the fact, that they could have found a better way to handle a problem. No parent gets it right every time. Even experts on child development sometimes make mistakes with their own children.
Of course, some mistakes cannot be tolerated. There is never an excuse for abuse or neglect, or for household dangers that imperil children?s lives. But young children will inevitably miss a meal, scrape their knees, or overhear their parents argue. They can easily survive the ordinary ups and downs of daily life, as long as the care they receive day by day is usually warm, responsive, and consistent. In fact, these ups and downs are among the experiences that help their brains to mature. What?s more, when children have a secure attachment to the adults who care for them, they are forgiving. When a parent disappoints them, they usually offer another chance.
[Introduction] |
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[III. We Know What Works] |