One study found that english speaking adults could relearn

CHAPTER 4: Developing Through the Life Span

Life is a journey, from womb to tomb. So it is for me, and so it will be for you. My story, and yours, began when a man and a woman contributed 20,000+ genes to an egg that became a unique person. Those genes coded the protein building blocks that, with astonishing precision, formed our bodies and predisposed our traits. My grandmother bequeathed to my mother a rare hearing-loss pattern, which she, in turn, gave to me (the least of her gifts). My father was an amiable extravert, and sometimes I forget to stop talking. As a child, my talking was impeded by painful stuttering, for which Seattle Public Schools gave me speech therapy.

Along with my parents’ nature, I also received their nurture. Like you, I was born into a particular family and culture, with its own way of viewing the world. My values have been shaped by a family culture filled with talking and laughter, by a religious culture that speaks of love and justice, and by an academic culture that encourages critical thinking (asking, What do you mean? How do you know?).

We are formed by our genes, and by our contexts, so our stories will differ. But in many ways we are each like nearly everyone else on Earth. Being human, you and I have a need to belong. My mental video library, which began after age 4, is filled with scenes of social attachment. Over time, my attachments to parents loosened as peer friendships grew. After lacking confidence to date in high school, I fell in love with a college classmate and married at age 20. Natural selection disposes us to survive and perpetuate our genes. Sure enough, two years later a child entered our lives and I experienced a new form of love that surprised me with its intensity.

But life is marked by change. That child now lives 2000 miles away, and one of his two siblings has found her calling in South Africa. The tight rubber bands linking parent and child have loosened, as yours likely have as well.

Change also marks most vocational lives, which for me transitioned from a teen working in the family insurance agency, to a premed chemistry major and hospital aide, to (after discarding my half-completed medical school applications) a psychology professor and author. I predict that in 10 years you, too, will be doing things you do not currently anticipate.

Stability also marks our development. When I look in the mirror I do not see the person I once was, but I feel like the person I have always been. I am the same person who, as a late teen, played basketball and discovered love. A half-century later, I still play basketball and still love (with less passion but more security) the life partner with whom I have shared life’s griefs and joys.

We experience a continuous self, but that self morphs through stages—growing up, raising children, enjoying a career, and, eventually, life’s final stage, which will demand my presence. As I wend my way through this cycle of life and death, I am mindful that life’s journey is a continuing process of development, seeded by nature and shaped by nurture, animated by love and focused by work, begun with wide-eyed curiosity and completed, for those blessed to live to a good old age, with peace and never-ending hope.

Across the life span we grow from newborn to toddler, from toddler to teenager, and from teen to mature adult. At each stage of life’s journey there are physical, cognitive, and social milestones. Let’s begin at the very beginning.

Developmental Psychology’s Major Issues

4-1: What three issues have engaged developmental psychologists?

Developmental psychology examines our physical, cognitive, and social development across the life span, with a focus on three major issues:

· 1. Nature and nurture: How does our genetic inheritance (our nature) interact with our experiences (our nurture) to influence our development? How have your nature and your nurture influenced your life story?

· 2. Continuity and stages: What parts of development are gradual and continuous, like riding an escalator? What parts change abruptly in separate stages, like climbing rungs on a ladder?

· 3. Stability and change: Which of our traits persist through life? How do we change as we age?

developmental psychology a branch of psychology that studies physical, cognitive, and social change throughout the life span.

“Nature is all that a man brings with him into the world; nurture is every influence that affects him after his birth.”

Francis Galton, English Men of Science, 1874

We will reflect on these three developmental issues throughout this chapter.

Prenatal Development and the Newborn

4-2: What is the course of prenatal development, and how do teratogens affect that development?

Conception

Nothing is more natural than a species reproducing itself. And nothing is more wondrous. With humans, the process starts when a woman’s ovary releases a mature egg—a cell roughly the size of the period at the end of this sentence. Like space voyagers approaching a huge planet, the 200 million or more deposited sperm begin their race upstream, approaching a cell 85,000 times their own size. The relatively few reaching the egg release digestive enzymes that eat away its protective coating. As soon as one sperm penetrates that coating and is welcomed in the egg’s surface blocks out the others. Before half a day elapses, the egg nucleus and the sperm nucleus fuse. The two have become one.

Consider it your most fortunate of moments. Among 200 million sperm, the one needed to make you, in combination with that one particular egg, won the race. And so it was for innumerable generations before us. If any one of our ancestors had been conceived with a different sperm or egg, or died before conceiving, or not chanced to meet the partner or … the mind boggles at the improbable, unbroken chain of events that produced you and me.

Prenatal Development

Fewer than half of all fertilized eggs, called zygotes, survive beyond the first 2 weeks (Grobstein, 1979; Hall, 2004). But for you and me, good fortune prevailed. One cell became 2, then 4—each just like the first—until this cell division had produced some 100 identical cells within the first week. Then the cells began to differentiate—to specialize in structure and function. How identical cells do this—as if one decides “I’ll become a brain, you become intestines!”—is a puzzle that scientists are just beginning to solve.

zygote the fertilized egg; it enters a 2-week period of rapid cell division and develops into an embryo.

About 10 days after conception, the zygote attaches to the mother’s uterine wall, beginning approximately 37 weeks of the closest human relationship. The zygote’s inner cells become the embryo. The outer cells become the placenta, the life-link that transfers nutrients and oxygen from mother to embryo. Over the next 6 weeks, the embryo’s organs begin to form and function. The heart begins to beat.

embryo the developing human organism from about 2 weeks after fertilization through the second month

By 9 weeks after conception, an embryo looks unmistakably human. It is now a fetus (Latin for “offspring” or “young one”). During the sixth month, organs such as the stomach have developed enough to give the fetus a chance of survival if born prematurely.

fetus the developing human organism from 9 weeks after conception to birth.

At each prenatal stage, genetic and environmental factors affect our development. By the sixth month, microphone readings taken inside the uterus reveal that the fetus is responsive to sound and is exposed to the sound of its mother’s muffled voice (Ecklund-Flores, 1992; Hepper, 2005). Immediately after birth, newborns prefer her voice to another woman’s or to their father’s (Busnel et al., 1992; DeCasper et al., 1984, 1986, 1994). They also prefer hearing their mother’s language. If she spoke two languages during pregnancy, they display interest in both (Byers-Heinlein et al., 2010). And just after birth, the melodic ups and downs of newborns’ cries bear the tuneful signature of their mother’s native tongue (Mampe et al., 2009). Babies born to French-speaking mothers tend to cry with the rising intonation of French; babies born to German-speaking mothers cry with the falling tones of German. Would you have guessed? The learning of language begins in the womb.

In the two months before birth, fetuses demonstrate learning in other ways, as when they adapt to a vibrating, honking device placed on their mother’s abdomen (Dirix et al., 2009). Like people who adapt to the sound of trains in their neighborhood, fetuses get used to the honking. Moreover, four weeks later, they recall the sound (as evidenced by their blasé response, compared with the reactions of those not previously exposed).

Sounds are not the only stimuli fetuses are exposed to in the womb. In addition to transferring nutrients and oxygen from mother to fetus, the placenta screens out many harmful substances, but some slip by. Teratogens, agents such as toxins, viruses, and drugs, can damage an embryo or fetus. This is one reason pregnant women are advised not to drink alcoholic beverages. A pregnant woman never drinks alone. As alcohol enters her bloodstream, and her fetus’, it depresses activity in both their central nervous systems. Alcohol use during pregnancy may prime the woman’s offspring to like alcohol and may put them at risk for heavy drinking and alcohol use disorder during their teens. In experiments, when pregnant rats drank alcohol, their young offspring later displayed a liking for alcohol’s taste and odor (Youngentob et al., 2007, 2009).

teratogens (literally, “monster maker”) agents, such as toxins, chemicals, and viruses, that can reach the embryo or fetus during prenatal development and cause harm.

Even light drinking or occasional binge drinking can affect the fetal brain (Braun, 1996; Ikonomidou et al., 2000; Sayal et al., 2009). Persistent heavy drinking puts the fetus at risk for birth defects and for future behavior problems, hyperactivity, and lower intelligence. For 1 in about 800 infants, the effects are visible as fetal alcohol syndrome (FAS), marked by a small, misproportioned head and lifelong brain abnormalities (May & Gossage, 2001). The fetal damage may occur because alcohol has what Chapter 2 called an epigenetic effect: It leaves chemical marks on DNA that switch genes abnormally on or off (Liu et al., 2009).

fetal alcohol syndrome (FAS) physical and cognitive abnormalities in children caused by a pregnant woman’s heavy drinking. In severe cases, symptoms include noticeable facial misproportions.

Prenatal development

zygote:

conception to 2 weeks

embryo:

2 weeks through 8 weeks

fetus:

9 weeks to birth

“You shall conceive and bear a son. So then drink no wine or strong drink.”

Judges 13:7

“I felt like a man trapped in a woman’s body. Then I was born.”

Comedian Chris Bliss

The Competent Newborn

4-3: What are some newborn abilities, and how do researchers explore infants’ mental abilities?

Babies come with software preloaded on their neural hard drives. Having survived prenatal hazards, we as newborns came equipped with automatic reflex responses ideally suited for our survival. We withdrew our limbs to escape pain. If a cloth over our face interfered with our breathing, we turned our head from side to side and swiped at it.

New parents are often in awe of the coordinated sequence of reflexes by which their baby gets food. When something touches their cheek, babies turn toward that touch, open their mouth, and vigorously root for a nipple. Finding one, they automatically close on it and begin sucking—which itself requires a coordinated sequence of reflexive tonguing, swallowing, and breathing. Failing to find satisfaction, the hungry baby may cry—a behavior parents find highly unpleasant and very rewarding to relieve.

The pioneering American psychologist William James presumed that newborns experience a “blooming, buzzing confusion,” an assumption few people challenged until the 1960s. Then scientists discovered that babies can tell you a lot—if you know how to ask. To ask, you must capitalize on what babies can do—gaze, suck, turn their heads. So, equipped with eye-tracking machines and pacifiers wired to electronic gear, researchers set out to answer parents’ age-old questions: What can my baby see, hear, smell, and think?

Prepared to feed and eat

Consider how researchers exploit habituation—a decrease in responding with repeated stimulation. We saw this earlier when fetuses adapted to a vibrating, honking device placed on their mother’s abdomen. The novel stimulus gets attention when first presented. With repetition, the response weakens. This seeming boredom with familiar stimuli gives us a way to ask infants what they see and remember.

habituation decreasing responsiveness with repeated stimulation. As infants gain familiarity with repeated exposure to a visual stimulus, their interest wanes and they look away sooner.

Indeed, even as newborns, we prefer sights and sounds that facilitate social responsiveness. We turn our heads in the direction of human voices. We gaze longer at a drawing of a face-like image. We prefer to look at objects 8 to 12 inches away, which—wonder of wonders—just happens to be the approximate distance between a nursing infant’s eyes and its mother’s (Maurer & Maurer, 1988).

Within days after birth, our brain’s neural networks were stamped with the smell of our mother’s body. Week-old nursing babies, placed between a gauze pad from their mother’s bra and one from another nursing mother, have usually turned toward the smell of their own mother’s pad (MacFarlane, 1978). What’s more, that smell preference lasts. One experiment capitalized on the fact that some nursing mothers in a French maternity ward used a chamomile-scented balm to prevent nipple soreness (Delaunay-El Allam, 2010). Twenty-one months later, their toddlers preferred playing with chamomile-scented toys! Their peers who had not sniffed the scent while breast feeding showed no such preference. (This makes me wonder: Will adults, who as babies associated chamomile scent with their mother’s breast, become devoted chamomile tea drinkers?)

Infancy and Childhood

As a flower unfolds in accord with its genetic instructions, so do we humans. Maturation—the orderly sequence of biological growth—decrees many of our commonalities. We stand before walking. We use nouns before adjectives. Severe deprivation or abuse can retard our development, but the genetic growth tendencies are inborn. Maturation (nature) sets the basic course of development; experience (nurture) adjusts it. Once again, we see genes and scenes interacting.

maturation biological growth processes that enable orderly changes in behavior, relatively uninfluenced by experience.

“It is a rare privilege to watch the birth, growth, and first feeble struggles of a living human mind.”

Annie Sullivan, in Helen Keller’s The Story of My Life, 1903

Physical Development

4-4: During infancy and childhood, how do the brain and motor skills develop?

Brain Development

The formative nurture that conspired with nature began at conception, with the prenatal environment in the womb. Nurture continues outside the womb, where our early experiences foster brain development.

In your mother’s womb, your developing brain formed nerve cells at the explosive rate of nearly one-quarter million per minute. From infancy on, brain and mind—neural hardware and cognitive software—develop together. On the day you were born, you had most of the brain cells you would ever have. However, the wiring among these cells—your nervous system—was immature: After birth, these neural networks had a wild growth spurt branching and linking in patterns that would eventually enable you to walk, talk, and remember.

From ages 3 to 6, the most rapid brain growth was in your frontal lobes, which enable rational planning. During those years, your ability to control your attention and behavior developed rapidly (Garon et al., 2008; Thompson-Schill et al., 2009).

Frontal lobe development continues into adolescence and beyond. The last cortical areas to develop are the association areas—those linked with thinking, memory, and language. As they develop, mental abilities surge (Chugani & Phelps, 1986; Thatcher et al., 1987). The neural pathways supporting language and agility proliferate into puberty. Then, a use-it-or-lose-it pruning processshuts down unused links and strengthens others (Paus et al., 1999; Thompson et al., 2000).

Stringing the circuits young

Your genes dictated your overall brain architecture, rather like the lines of a coloring book, but experience fills in the details (Kenrick et al., 2009). So how do early experiences leave their “marks” in the brain? Mark Rosenzweig and David Krech opened a window on that process when they raised some young rats in solitary confinement in an impoverished environment, and others in a communal playground that simulated a natural environment. When the researchers later analyzed the rats’ brains, those who died with the most toys had won. The rats living in the enriched environment had usually developed a heavier and thicker brain cortex.

Rosenzweig was so surprised by this discovery that he repeated the experiment several times before publishing his findings (Renner & Rosenzweig, 1987; Rosenzweig, 1984). So great are the effects that, shown brief video clips, you could tell from the rats’ activity and curiosity whether their environment had been impoverished or enriched (Renner & Renner, 1993). After 60 days in the enriched environment, the rats’ brain weights increased 7 to 10 percent and the number of synapses mushroomed by about 20 percent (Kolb & Whishaw, 1998).

Such results have motivated improvements in environments for laboratory, farm, and zoo animals—and for children in institutions. Stimulation by touch or massage also benefits infant rats and premature babies (Field et al., 2007). “Handled” infants of both species develop faster neurologically and gain weight more rapidly. By giving preemies massage therapy, neonatal intensive care units help them to go home sooner (Field et al., 2006).

Nature and nurture together sculpt our synapses. Brain maturation provides us with an abundance of neural connections. Experiences—sights and smells, touches and tugs—activate and strengthen some neural pathways while others weaken from disuse. Like forest pathways, popular tracks are broadened and less-traveled ones gradually disappear. The result by puberty is a massive loss of unemployed connections.

Here at the juncture of nurture and nature is the biological reality of early childhood learning. During early childhood—while excess connections are still on call—youngsters can most easily master such skills as the grammar and accent of another language. We seem to have a critical period for some skills. Lacking any exposure to spoken, written, or signed language before adolescence, a person will never master any language. Likewise, lacking visual experience during the early years, a person whose vision is restored by cataract removal will never achieve normal perceptions. Without stimulation, the brain cells normally assigned to vision will die during the pruning process or be diverted to other uses. The maturing brain’s rule: Use it or lose it.

critical period an optimal period early in the life of an organism when exposure to certain stimuli or experiences produces normal development.

Although normal stimulation during the early years is critical, the brain’s development does not end with childhood. As we saw in Chapter 2’s discussion of brain plasticity, our neural tissue is ever changing and new neurons are born. If a monkey pushes a lever with the same finger several thousand times a day, brain tissue controlling that finger changes to reflect the experience. Human brains work similarly. Whether learning to keyboard or skateboard, we perform with increasing skill as our brain incorporates the learning (Ambrose, 2010).

“Genes and experiences are just two ways of doing the same thing—wiring synapses.”

Joseph LeDoux, The Synaptic Self, 2002

Motor Development

The developing brain enables physical coordination. As an infant’s muscles and nervous system mature, skills emerge. With occasional exceptions, the sequence of physical (motor) development is universal. Babies roll over before they sit unsupported, and they usually crawl on all fours before they walk. These behaviors reflect not imitation but a maturing nervous system; blind children, too, crawl before they walk.

There are, however, individual differences in timing. In the United States, for example, 25 percent of all babies walk by 11 months of age, 50 percent within a week after their first birthday, and 90 percent by age 15 months (Frankenburg et al., 1992). The recommended infant back-to-sleep position (putting babies to sleep on their backs to reduce the risk of a smothering crib death) has been associated with somewhat later crawling but not with later walking (Davis et al., 1998; Lipsitt, 2003).

In the eight years following the 1994 launch of a U.S. Back to Sleep educational campaign, the number of infants sleeping on their stomach dropped from 70 to 11 percent—and SIDS (sudden infant death syndrome) deaths fell by half (Braiker, 2005).

Genes guide motor development. Identical twins typically begin walking on nearly the same day (Wilson, 1979). Maturation—including the rapid development of the cerebellum at the back of the brain—creates our readiness to learn walking at about age 1. Experience before that time has a limited effect. The same is true for other physical skills, including bowel and bladder control. Before necessary muscular and neural maturation, neither pleading nor punishment will produce successful toilet training.

Brain Maturation and Infant Memory

Can you recall your first day of preschool or your third birthday party? Our earliest memories seldom predate our third birthday. We see this infantile amnesia in the memories of some preschoolers who experienced an emergency fire evacuation caused by a burning popcorn maker. Seven years later, they were able to recall the alarm and what caused it—if they were 4 to 5 years old at the time. Those experiencing the event as 3-year-olds could not remember the cause and usually misrecalled being already outside when the alarm sounded (Pillemer, 1995). Other studies have confirmed that the average age of earliest conscious memory is 3.5 years (Bauer, 2002, 2007). As children mature, from 4 to 6 to 8 years, childhood amnesia is giving way, and they become increasingly capable of remembering experiences, even for a year or more (Bruce et al., 2000; Morris et al., 2010). The brain areas underlying memory, such as the hippocampus and frontal lobes, continue to mature into adolescence (Bauer, 2007).

Although we consciously recall little from before age 4, our brain was processing and storing information during those early years. In 1965, while finishing her doctoral work in psychology, Carolyn Rovee-Collier observed an infant memory. She was a new mom, whose colicky 2-month-old, Benjamin, could be calmed by moving a crib mobile. Weary of hitting the mobile, she strung a cloth ribbon connecting the mobile to Benjamin’s foot. Soon, he was kicking his foot to move the mobile. Thinking about her unintended home experiment, Rovee-Collier realized that, contrary to popular opinion in the 1960s, babies are capable of learning. To know for sure that her son wasn’t just a whiz kid, she repeated the experiment with other infants (Rovee-Collier, 1989, 1999). Sure enough, they, too, soon kicked more when hitched to a mobile, both on the day of the experiment and the day after. They had learned the link between moving legs and moving mobiles. If, however, she hitched them to a different mobile the next day, the infants showed no learning, indicating that they remembered the original mobile and recognized the difference. Moreover, when tethered to the familiar mobile a month later, they remembered the association and again began kicking.

Traces of forgotten childhood languages may also persist. One study tested English-speaking British adults who had no conscious memory of the Hindi or Zulu they had spoken as children. Yet, up to age 40, they could relearn subtle sound contrasts in these languages that other people could notlearn (Bowers et al., 2009). What the conscious mind does not know and cannot express in words, the nervous system and our two-track mind somehow remembers.

Cognitive Development

4-5: From the perspectives of Piaget, Vygotsky, and today’s researchers, how does a child’s mind develop?

Cognition refers to all the mental activities associated with thinking, knowing, remembering, and communicating. Somewhere on your life journey, you became conscious. When was that, and how did your mind unfold from there? Developmental psychologist Jean Piaget [pee-ah-ZHAY] spent his life searching for the answers to such questions. His interest began in 1920, when he was in Paris developing questions for children’s intelligence tests. While administering the tests, Piaget became intrigued by children’s wrong answers, which were often strikingly similar among same-age children. Where others saw childish mistakes, Piaget saw intelligence at work.

cognition all the mental activities associated with thinking, knowing, remembering, and communicating.

A half-century spent with children convinced Piaget that a child’s mind is not a miniature model of an adult’s. Thanks partly to his work, we now understand that children reason differently than adults, in “wildly illogical ways about problems whose solutions are self-evident to adults” (Brainerd, 1996).

Jean Piaget (1896–1980)

Piaget’s studies led him to believe that a child’s mind develops through a series of stages, in an upward march from the newborn’s simple reflexes to the adult’s abstract reasoning power. Thus, an 8-year-old can comprehend things a toddler cannot, such as the analogy that “getting an idea is like having a light turn on in your head,” or that a miniature slide is too small for sliding, and a miniature car is much too small to get into.

Piaget’s core idea is that the driving force behind our intellectual progression is an unceasing struggle to make sense of our experiences. To this end, the maturing brain builds schemas, concepts or mental molds into which we pour our experiences. By adulthood we have built countless schemas, ranging from cats and dogs to our concept of love.

schema a concept or framework that organizes and interprets information.

To explain how we use and adjust our schemas, Piaget proposed two more concepts. First, we assimilate new experiences—we interpret them in terms of our current understandings (schemas). Having a simple schema for dog, for example, a toddler may call all four-legged animals dogs. But as we interact with the world, we also adjust, or accommodate, our schemas to incorporate information provided by new experiences. Thus, the child soon learns that the original dog schema is too broad and accommodates by refining the category.

assimilation interpreting our new experiences in terms of our existing schemas.

accommodation adapting our current understandings (schemas) to incorporate new information.

Piaget’s Theory and Current Thinking

Piaget believed that children construct their understanding of the world while interacting with it. Their minds experience spurts of change, followed by greater stability as they move from one cognitive plateau to the next, each with distinctive characteristics that permit specific kinds of thinking. TABLE 4.1 summarizes the four stages in Piaget’s theory.

Table 4.1: Piaget’s Stages of Cognitive Development

Typical Age Range

Description of Stage

Developmental Phenomena

Birth to nearly 2 years

Sensorimotor

Experiencing the world through senses and actions (looking, hearing, touching, mouthing, and grasping)

· Object permanence

· Stranger anxiety

About 2 to about 6 or 7 years

Preoperational

Representing things with words and images; using intuitive rather than logical reasoning

· Pretend play

· Egocentrism

About 7 to 11 years

Concrete operational

Thinking logically about concrete events; grasping concrete analogies and performing arithmetical operations

· Conservation

· Mathematical transformations

About 12 through adulthood

Formal operational

Abstract reasoning

· Abstract logic

· Potential for mature moral reasoning

Sensorimotor Stage

In the sensorimotor stage, from birth to nearly age 2, babies take in the world through their senses and actions—through looking, hearing, touching, mouthing, and grasping. As their hands and limbs begin to move, they learn to make things happen.

sensorimotor stage in Piaget’s theory, the stage (from birth to about 2 years of age) during which infants know the world mostly in terms of their sensory impressions and motor activities.

Very young babies seem to live in the present: Out of sight is out of mind. In one test, Piaget showed an infant an appealing toy and then flopped his beret over it. Before the age of 6 months, the infant acted as if the toy ceased to exist. Young infants lack object permanence—the awareness that objects continue to exist when not perceived. By 8 months, infants begin exhibiting memory for things no longer seen. If you hide a toy, the infant will momentarily look for it. Within another month or two, the infant will look for it even after being restrained for several seconds.

object permanence the awareness that things continue to exist even when not perceived.

So does object permanence in fact blossom at 8 months, much as tulips blossom in spring? Today’s researchers think not. They believe object permanence unfolds gradually, and they see development as more continuous than Piaget did. Even young infants will at least momentarily look for a toy where they saw it hidden a second before (Wang et al., 2004).

Researchers also believe Piaget and his followers underestimated young children’s competence. Consider these simple experiments:

· Baby physics: Like adults staring in disbelief at a magic trick (the “Whoa!” look), infants look longer at an unexpected and unfamiliar scene of a car seeming to pass through a solid object, a ball stopping in midair, or an object violating object permanence by magically disappearing (Baillargeon, 1995, 2008; Wellman & Gelman, 1992).

· Baby math: Karen Wynn (1992, 2000) showed 5-month-olds one or two objects. Then she hid the objects behind a screen, and visibly removed or added one. When she lifted the screen, the infants sometimes did a double take, staring longer when shown a wrong number of objects. But were they just responding to a greater or smaller mass of objects, rather than a change in number (Feigenson et al., 2002)? Later experiments showed that babies’ number sense extends to larger numbers, to ratios, and to such things as drumbeats and motions (Libertus & Brannon, 2009; McCrink & Wynn, 2004; Spelke & Kinzler, 2007). If accustomed to a Daffy Duck puppet jumping three times on stage, they showed surprise if it jumped only twice.

Clearly, infants are smarter than Piaget appreciated. Even as babies, we had a lot on our minds.

Preoperational Stage

Piaget believed that until about age 6 or 7, children are in a preoperational stage—too young to perform mental operations (such as imagining an action and mentally reversing it). For a 5-year-old, the milk that seems “too much” in a tall, narrow glass may become an acceptable amount if poured into a short, wide glass. Focusing only on the height dimension, this child cannot perform the operation of mentally pouring the milk back. Before about age 6, said Piaget, children lack the concept of conservation—the principle that quantity remains the same despite changes in shape.

preoperational stage in Piaget’s theory, the stage (from about 2 to about 6 or 7 years of age) during which a child learns to use language but does not yet comprehend the mental operations of concrete logic.

conservation the principle (which Piaget believed to be a part of concrete operational reasoning) that properties such as mass, volume, and number remain the same despite changes in the forms of objects.

PRETEND PLAY A child who can perform mental operations can think in symbols and therefore begins to enjoy pretend play. Contemporary researchers have found that symbolic thinking appears at an earlier age than Piaget supposed. Judy DeLoache (1987) showed children a model of a room and hid a miniature stuffed dog behind its miniature couch. The 2½-year-olds easily remembered where to find the miniature toy, but they could not use the model to locate an actual stuffed dog behind a couch in a real room. Three-year-olds—only 6 months older—usually went right to the actual stuffed animal in the real room, showing they could think of the model as a symbol for the room. Piaget did not view the stage transitions as abrupt shifts. Even so, he probably would have been surprised to see symbolic thinking at such an early age.

EGOCENTRISM Piaget contended that preschool children are egocentric: They have difficulty perceiving things from another’s point of view. Asked to “show Mommy your picture,” 2-year-old Gabriella holds the picture up facing her own eyes. Three-year-old Gray makes himself “invisible” by putting his hands over his eyes, assuming that if he can’t see his grandparents, they can’t see him. Children’s conversations also reveal their egocentrism, as one young boy demonstrated (Phillips, 1969, p. 61):

“Do you have a brother?”

“Yes.”

“What’s his name?”

“Jim.”

“Does Jim have a brother?”

“No.”

egocentrism in Piaget’s theory, the preoperational child’s difficulty taking another’s point of view.

Like Gabriella, TV-watching preschoolers who block your view of the TV assume that you see what they see. They simply have not yet developed the ability to take another’s viewpoint. Even we adults may overestimate the extent to which others share our opinions and perspectives, a trait known as the curse of knowledge. We assume that something will be clear to others if it is clear to us, or that e-mail recipients will “hear” our “just kidding” intent (Epley et al., 2004; Kruger et al., 2005). Children are even more susceptible to such egocentrism.

THEORY OF MIND When Little Red Riding Hood realized her “grandmother” was really a wolf, she swiftly revised her ideas about the creature’s intentions and raced away. Preschoolers, although still egocentric, develop this ability to infer others’ mental states when they begin forming a theory of mind (a term first coined by psychologists David Premack and Guy Woodruff [1978], to describe chimpanzees’ seeming ability to read intentions).

theory of mind people’s ideas about their own and others’ mental states—about their feelings, perceptions, and thoughts, and the behaviors these might predict.

As the ability to take another’s perspective gradually develops, preschoolers come to understand what made a playmate angry, when a sibling will share, and what might make a parent buy a toy. And they begin to tease, empathize, and persuade. Between about 3½ and 4½, children worldwide come to realize that others may hold false beliefs (Callaghan et al., 2005; Sabbagh et al., 2006). Jennifer Jenkins and Janet Astington (1996) showed Toronto children a Band-Aids box and asked them what was inside. Expecting Band-Aids, the children were surprised to discover that the box actually contained pencils. Asked what a child who had never seen the box would think was inside, 3-year-olds typically answered “pencils.” By age 4 to 5, the children’s theory of mind had leapt forward, and they anticipated their friends’ false belief that the box would hold Band-Aids. Children with autism spectrum disorder have difficulty understanding that another’s state of mind differs from their own.

Concrete Operational Stage

By age 6 or 7, said Piaget, children enter the concrete operational stage. Given concrete (physical) materials, they begin to grasp conservation. Understanding that change in form does not mean change in quantity; they can mentally pour milk back and forth between glasses of different shapes. They also enjoy jokes that use this new understanding:

concrete operational stage in Piaget’s theory, the stage of cognitive development (from about 6 or 7 to 11 years of age) during which children gain the mental operations that enable them to think logically about concrete events.

Mr. Jones went into a restaurant and ordered a whole pizza for his dinner. When the waiter asked if he wanted it cut into 6 or 8 pieces, Mr. Jones said, “Oh, you’d better make it 6, I could never eat 8 pieces!” (McGhee, 1976)

Piaget believed that during the concrete operational stage, children become able to comprehend mathematical transformations and conservation. When my daughter, Laura, was 6, I was astonished at her inability to reverse simple arithmetic. Asked, “What is 8 plus 4?” she required 5 seconds to compute “12,” and another 5 seconds to then compute 12 minus 4. By age 8, she could answer a reversed question instantly.

Formal Operational Stage

By about age 12, our reasoning expands from the purely concrete (involving actual experience) to encompass abstract thinking (involving imagined realities and symbols). As children approach adolescence, said Piaget, many become capable of thinking more like scientists. They can ponder hypothetical propositions and deduce consequences: If this, then that. Systematic reasoning, what Piaget called formal operational thinking, is now within their grasp.

formal operational stage in Piaget’s theory, the stage of cognitive development (normally beginning about age 12) during which people begin to think logically about abstract concepts.

Although full-blown logic and reasoning await adolescence, the rudiments of formal operational thinking begin earlier than Piaget realized. Consider this simple problem:

If John is in school, then Mary is in school. John is in school. What can you say about Mary?

Formal operational thinkers have no trouble answering correctly. But neither do most 7-year-olds (Suppes, 1982).

An Alternative Viewpoint: Lev Vygotsky and the Social Child

As Piaget was forming his theory of cognitive development, Russian psychologist Lev Vygotsky (1896–1934) was also studying how children think and learn. He noted that by age 7, they increasingly think in words and use words to solve problems. They do this, he said, by internalizing their culture’s language and relying on inner speech (Fernyhough, 2008). Parents who say “No, no!”when pulling a child’s hand away from a cake are giving the child a self-control tool. When the child later needs to resist temptation, he may likewise say “No, no!” Second-graders who muttered to themselves while doing math problems grasped third-grade math better the following year (Berk, 1994). Whether out loud or inaudibly, talking to themselves helps children control their behavior and emotions and master new skills.

Lev Vygotsky (1896–1934)

Where Piaget emphasized how the child’s mind grows through interaction with the physical environment, Vygotsky emphasized how the child’s mind grows through interaction with the socialenvironment. If Piaget’s child was a young scientist, Vygotsky’s was a young apprentice. By mentoring children and giving them new words, parents and others provide a temporary scaffoldfrom which children can step to higher levels of thinking (Renninger & Granott, 2005). Language, an important ingredient of social mentoring, provides the building blocks for thinking, noted Vygotsky (who was born the same year as Piaget, but died prematurely of tuberculosis).

Reflecting on Piaget’s Theory

What remains of Piaget’s ideas about the child’s mind? Plenty—enough to merit his being singled out by Time magazine as one of the twentieth century’s 20 most influential scientists and thinkers and rated in a survey of British psychologists as the last century’s greatest psychologist (Psychologist, 2003). Piaget identified significant cognitive milestones and stimulated worldwide interest in how the mind develops. His emphasis was less on the ages at which children typically reach specific milestones than on their sequence. Studies around the globe, from aboriginal Australia to Algeria to North America, have confirmed that human cognition unfolds basically in the sequence Piaget described (Lourenco & Machado, 1996; Segall et al., 1990).

However, today’s researchers see development as more continuous than did Piaget. By detecting the beginnings of each type of thinking at earlier ages, they have revealed conceptual abilities Piaget missed. Moreover, they view formal logic as a smaller part of cognition than he did. Piaget would not be surprised that today, as part of our own cognitive development, we are adapting his ideas to accommodate new findings.

“Assessing the impact of Piaget on developmental psychology is like assessing the impact of Shakespeare on English literature.”

Developmental psychologist Harry Beilin (1992)

CLOSE UP: Autism Spectrum Disorder and “Mind-Blindness”

Diagnoses of autism spectrum disorder (ASD), a disorder marked by social deficiencies, have been increasing. Once believed to affect 1 in 2500 children, ASD now affects 1 in 110 American children and about 1 in 100 in Britain (CDC, 2009; Lilienfeld & Arkowitz, 2007; NAS, 2011). The increase in ASD diagnoses has been offset by a decrease in the number of children considered “cognitively disabled” or “learning disabled,” which suggests a relabeling of children’s disorders (Gernsbacher et al., 2005; Grinker, 2007; Shattuck, 2006). A massive $6.7 billion National Children’s Study now under way aims to enroll 100,000 pregnant women in 105 countries and to follow their babies until they turn 21. Researchers hope this study will help explain the rising rates of ASD, as well as premature births, childhood obesity, and asthma (Belluck, 2010; Murphy, 2008).

autism spectrum disorder (ASD) a disorder that appears in childhood and is marked by deficient communication, social interaction, and understanding of others’ states of mind.

The underlying source of ASD’s symptoms seems to be poor communication among brain regions that normally work together to let us take another’s viewpoint. This effect appears to result from ASD-related genes interacting with the environment (State Šestan, 2012). People with ASD are therefore said to have an impaired theory of mind (Rajendran & Mitchell, 2007; Senju et al., 2009). They have difficulty inferring others’ thoughts and feelings. They do not appreciate that playmates and parents might view things differently. Mind reading that most of us find intuitive (Is that face conveying a smirk or a sneer?) is difficult for those with ASD. Most children learn that another child’s pouting mouth signals sadness, and that twinkling eyes mean happiness or mischief. A child with ASD fails to understand these signals (Frith & Frith, 2001). In hopes of a cure, desperate parents have sometimes subjected children to ineffective therapies (Shute, 2010).

Autism spectrum disorder

This speech-language pathologist is helping a boy with ASD learn to form sounds and words. ASD is marked by deficient social communication and difficulty grasping others’ states of mind.

Ozier Muhammad/The New York Times/Redux

ASD (formerly referred to as “autism”) has differing levels of severity. “High- functioning” individuals have normal intelligence, and they often have an exceptional skill or talent in a specific area. But they lack social and communication skills, and they tend to become distracted by minor and unimportant stimuli (Remington et al., 2009). Those at the spectrum’s lower end are unable to use language at all.

ASD afflicts four boys for every girl. Psychologist Simon Baron-Cohen believes this hints at one way to understand this disorder. He has argued that ASD represents an “extreme male brain” (2008, 2009). Although there is some overlap between the sexes, he believes that boys are better “systemizers.” They tend to understand things according to rules or laws, for example, as in mathematical and mechanical systems. Children exposed to high levels of the male sex hormone testosterone in the womb may develop more masculine and autistic traits (Auyeung et al, 2009).

In contrast, girls are naturally predisposed to be “empathizers,” Baron-Cohen contends. They are better at reading facial expressions and gestures, though less so if given testosterone (van Honk et al, 2011).

Biological factors, including genetic influences and abnormal brain development, contribute to ASD (State Šestan, 2012). Childhood MMR vaccinations do not (Demicheli et al., 2012). Based on a fraudulent 1998 study—the most damaging medical hoax of the last 100 years” (Flaherty, 2011)—some parents were misled into thinking that the childhood MMR vaccine increased risk of ASD. The unfortunate result was a drop in vaccination rates and an increase in cases of measles and mumps. Some unvaccinated children suffered long-term harm or even death.

Twin and sibling studies provide some evidence for biology’s influence. If one identical twin is diagnosed with ASD, the chances are 50 to 70 percent that the co-twin will also receive this diagnosis (Lichtenstein et al., 2010; Sebat et al., 2007). A younger sibling of a child with ASD also is at a heightened risk (Sutcliffe, 2008). Random genetic mutations in sperm-producing cells may also play a role. As men age, these mutations become more frequent, which may help explain why an over-40 man has a much higher risk of fathering a child with ASD than does a man under 30 (Reichenberg et al., 2007). Researchers are now sleuthing ASD’s telltale signs in the brain’s synaptic and gray matter (Crawley, 2007; Ecker et al., 2010; Garber, 2007).

“Autism” case number 1

In 1943, Donald Gray Triplett, an “odd” child with unusual gifts and social deficits, was the first person to receive the diagnosis of a previously unreported condition, which psychiatrist Leo Kanner termed “autism.” (After a 2013 change in the diagnosis manual, his condition is now called autism spectrum disorder.) In 2010, at age 77, Triplett was still living in his native home and Mississippi town, where he often played golf (Donvan & Zucker, 2010).

Biology’s role in ASD also appears in brain-function studies. People without ASD often yawn after seeing others yawn. And as they view and imitate another’s smiling or frowning, they feel something of what the other is feeling. Not so among those with ASD, who are less imitative and show much less activity in brain areas involved in mirroring others’ actions (Dapretto et al., 2006; Perra et al., 2008; Senju et al., 2007). When people with ASD watch another person’s hand movements, for example, their brain displays less-than-normal mirroring activity (Oberman & Ramachandran, 2007; Théoret et al., 2005). Scientists are continuing to explore and vigorously debate the idea that the brains of people with ASD have “broken mirrors” (Gallese et al., 2011).

Seeking to “systemize empathy,” Baron-Cohen and his Cambridge University colleagues (2007; Golan et al., 2010) collaborated with Britain’s National Autistic Society and a film production company. Knowing that television shows with vehicles have been popular among kids with ASD, they created animations with toy vehicle characters in a pretend boy’s bedroom, grafting emotion-conveying faces onto toy trams, trains, and tractors. After the boy leaves for school, the characters come to life and have experiences that lead them to display various emotions ( www.thetransporters.com ). The children were surprisingly able to generalize what they had learned to a new, real context. By the intervention’s end, their previously deficient ability to recognize emotions on real faces equaled that of children without ASD.

Implications for Parents and Teachers

Future parents and teachers, remember this: Young children are incapable of adult logic. Preschoolers who block one’s view of the TV simply have not learned to take another’s viewpoint. What seems simple and obvious to us—getting off a teeter-totter will cause a friend on the other end to crash—may be incomprehensible to a 3-year-old. Also remember that children are not passive receptacles waiting to be filled with knowledge. Better to build on what they already know, engaging them in concrete demonstrations and stimulating them to think for themselves. Finally, accept children’s cognitive immaturity as adaptive. It is nature’s strategy for keeping children close to protective adults and providing time for learning and socialization (Bjorklund & Green, 1992).

“Childhood has its own way of seeing, thinking, and feeling, and there is nothing more foolish than the attempt to put ours in its place.”

Philosopher Jean-Jacques Rousseau, 1798

Social Development

4-6: How do parent-infant attachment bonds form?

From birth, babies are social creatures, developing an intense bond with their caregivers. Infants come to prefer familiar faces and voices, then to coo and gurgle when given a parent’s attention. After about 8 months, soon after object permanence emerges and children become mobile, a curious thing happens: They develop stranger anxiety. They may greet strangers by crying and reaching for familiar caregivers. “No! Don’t leave me!” their distress seems to say. Children this age have schemas for familiar faces; when they cannot assimilate the new face into these remembered schemas, they become distressed (Kagan, 1984). Once again, we see an important principle: The brain, mind, and social-emotional behavior develop together.

stranger anxiety the fear of strangers that infants commonly display, beginning by about 8 months of age.

Origins of Attachment

One-year-olds typically cling tightly to a parent when they are frightened or expect separation. Reunited after being apart, they shower the parent with smiles and hugs. No social behavior is more striking than the intense and mutual infant-parent bond. This attachment bond is a powerful survival impulse that keeps infants close to their caregivers. Infants become attached to those—typically their parents—who are comfortable and familiar. For many years, psychologists reasoned that infants became attached to those who satisfied their need for nourishment. It made sense. But an accidental finding overturned this explanation.

attachment an emotional tie with another person; shown in young children by their seeking closeness to the caregiver and showing distress on separation.

Stranger anxiety

Body Contact

During the 1950s, University of Wisconsin psychologists Harry Harlow and Margaret Harlow bred monkeys for their learning studies. To equalize experiences and to isolate any disease, they separated the infant monkeys from their mothers shortly after birth and raised them in sanitary individual cages, which included a cheese-cloth baby blanket (Harlow et al., 1971). Then came a surprise: When their blankets were taken to be laundered, the monkeys became distressed.

The Harlows recognized that this intense attachment to the blanket contradicted the idea that attachment derives from an association with nourishment. But how could they show this more convincingly? To pit the drawing power of a food source against the contact comfort of the blanket, they created two artificial mothers. One was a bare wire cylinder with a wooden head and an attached feeding bottle, the other a cylinder wrapped with terry cloth.

When raised with both, the monkeys overwhelmingly preferred the comfy cloth mother. Like other infants clinging to their live mothers, the monkey babies would cling to their cloth mothers when anxious. When exploring their environment, they used her as a secure base, as if attached to her by an invisible elastic band that stretched only so far before pulling them back. Researchers soon learned that other qualities—rocking, warmth, and feeding—made the cloth mother even more appealing.

Human infants, too, become attached to parents who are soft and warm and who rock, feed, and pat. Much parent-infant emotional communication occurs via touch (Hertenstein et al., 2006), which can be either soothing (snuggles) or arousing (tickles). Human attachment also consists of one person providing another with a secure base from which to explore and a safe haven when distressed. As we mature, our secure base and safe haven shift—from parents to peers and partners (Cassidy & Shaver, 1999). But at all ages we are social creatures. We gain strength when someone offers, by words and actions, a safe haven: “I will be here. I am interested in you. Come what may, I will support you” (Crowell & Waters, 1994).

Familiarity

Contact is one key to attachment. Another is familiarity. In many animals, attachments based on familiarity form during a critical period—an optimal period when certain events must take place to facilitate proper development (Bornstein, 1989). As noted earlier, humans seem to have a critical period for language. Goslings, ducklings, and chicks have a critical period for attachment, called imprinting, which falls in the hours shortly after hatching, when the first moving object they see is normally their mother. From then on, the young fowl follow her, and her alone.

imprinting the process by which certain animals form attachments during a critical period very early in life.

Konrad Lorenz (1937) explored this rigid attachment process. He wondered: What would ducklings do if he was the first moving creature they observed? What they did was follow him around: Everywhere that Konrad went, the ducks were sure to go. Although baby birds imprint best to their own species, they also will imprint on a variety of moving objects—an animal of another species, a box on wheels, a bouncing ball (Colombo, 1982; Johnson, 1992). Once formed, this attachment is difficult to reverse.

Children—unlike ducklings—do not imprint. However, they do become attached to what they’ve known. Mere exposure to people and things fosters fondness. Children like to reread the same books, rewatch the same movies, and reenact family traditions. They prefer to eat familiar foods, live in the same familiar neighborhood, and attend school with the same old friends. Familiarity is a safety signal. Familiarity breeds content.

Attachment Differences

4-7: How have psychologists studied attachment differences, and what have they learned?

What accounts for children’s attachment differences? To answer this question, Mary Ainsworth (1979) designed the strange situation experiment. She observed mother-infant pairs at home during their first six months. Later she observed the 1-year-old infants in a strange situation (usually a laboratory playroom). Such research has shown that about 60 percent of infants display secure attachment. In their mother’s presence they play comfortably, happily exploring their new environment. When she leaves, they become distressed; when she returns, they seek contact with her.

Other infants avoid attachment or show insecure attachment, marked either by anxiety or avoidance of trusting relationships. They are less likely to explore their surroundings; they may even cling to their mother. When she leaves, they either cry loudly and remain upset or seem indifferent to her departure and return (Ainsworth, 1973, 1989; Kagan, 1995; van IJzendoorn & Kroonenberg, 1988).

Ainsworth and others found that sensitive, responsive mothers—those who noticed what their babies were doing and responded appropriately—had infants who exhibited secure attachment (De Wolff & van IJzendoorn, 1997). Insensitive, unresponsive mothers—mothers who attended to their babies when they felt like doing so but ignored them at other times—often had infants who were insecurely attached. The Harlows’ monkey studies, with unresponsive artificial mothers, produced even more striking effects. When put in strange situations without their artificial mothers, the deprived infants were terrified.

But is attachment style the result of parenting? Or are other factors also at work?

Temperament and Attachment

How does temperament—a person’s characteristic emotional reactivity and intensity—affect attachment style? Temperament is genetically influenced. Shortly after birth, some babies are noticeably difficult—irritable, intense, and unpredictable. Others are easy—cheerful, relaxed, and feeding and sleeping on predictable schedules (Chess & Thomas, 1987).

temperament a person’s characteristic emotional reactivity and intensity.

The genetic effect appears in physiological differences. Anxious, inhibited infants have high and variable heart rates and a reactive nervous system. When facing new or strange situations, they become more physiologically aroused (Kagan & Snidman, 2004). One form of a gene that regulates the neurotransmitter serotonin predisposes a fearful temperament and, in combination with unsupportive caregiving, an inhibited child (Fox et al., 2007).

Temperament differences typically persist. Consider:

· The most emotionally reactive newborns have tended also to be the most reactive 9-month-olds (Wilson & Matheny, 1986; Worobey & Blajda, 1989).

· Exceptionally inhibited and fearful 2-year-olds often were still relatively shy as 8-year-olds; about half became introverted adolescents (Kagan et al., 1992, 1994).

· The most emotionally intense preschoolers have tended to be relatively intense young adults (Larsen & Diener, 1987). In one long-term study of more than 900 New Zealanders, emotionally reactive and impulsive 3-year-olds developed into somewhat more impulsive, aggressive, and conflict-prone 21-year-olds (Caspi, 2000).