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As a flower unfolds in accord with its genetic instructions, so do we. 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 slow development, yet genetic growth patterns are inborn. Maturation (nature) sets the basic course of development; experience (nurture) adjusts it. Genes and scenes interact.

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

Brain Development

Our formative nurture began at conception, with the prenatal environment in the womb. Nurture continued outside the womb, where our early experiences fostered brain development.

In your mother’s womb, your developing brain formed nerve cells at the explosive rate of nearly one-quarter million per minute. 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 (FIGURE 4.5). This rapid development helps explain why infant brain size increases rapidly in the early days after birth (Holland et al., 2014).

From ages 3 to 6, the most rapid brain growth was in your frontal lobes, which enable rational planning. During those years, your brain required vast amounts of energy (Kuzawa et al., 2014). This energy-intensive process caused rapid progress in your ability to control your attention and behavior (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 agility, language, and self-control proliferate into puberty. Under the influence of adrenal hormones, tens of billions of synapses form and organize, while a use-it-or-lose-it pruning process shuts down unused links (Paus et al., 1999; Thompson et al., 2000).

Your genes dictate 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 “fingerprints” in the brain? Mark Rosenzweig, David Krech, and their colleagues (1962) opened a window on that process when they raised some young rats in solitary confinement, and others in a communal playground that simulated a natural environment. When the researchers later analyzed the rats’ brains, those living in the enriched environment had usually developed a heavier and thicker brain cortex (FIGURE 4.6 below). 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; Sarro et al., 2014). “Handled” infants of both species develop faster neurologically and gain weight more rapidly. Preemies who have had skin-to-skin contact with their mothers sleep better, experience less stress, and show better cognitive development 10 years later (Feldman et al., 2014).

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Nature and nurture interact to sculpt our synapses. Brain maturation provides us with an abundance of neural connections. Experiences—sights and smells, touches and tastes, music and movement—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 (Gregory, 1978; Wiesel, 1982). Without that early visual 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.

Although normal stimulation during the early years is critical, the brain’s development does not end with childhood. Thanks to the brain’s amazing plasticity, our neural tissue is ever changing and reorganizing in response to new experiences. New neurons also are born. If a monkey pushes a lever with the same finger many times a day, brain tissue controlling that finger changes to reflect the experience (FIGURE 4.7). Human brains work similarly. Whether learning to keyboard, skateboard, or navigate London’s streets, we perform with increasing skill as our brain incorporates the learning (Ambrose, 2010; Maguire et al., 2000).

Motor Development

The developing brain enables physical coordination. As an infant exercises its maturing muscles and nervous system, 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.

In the United States, 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). In some regions of Africa, the Caribbean, and India, caregivers frequently massage and exercise babies, which can accelerate the process of learning to walk (Karasik et al., 2010). 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).

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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. 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? Studies have confirmed that our average age of earliest conscious memory is 3.5 years (Bauer, 2002, 2007). But as children mature, by age 7 or so, infantile amnesia wanes, and they become increasingly capable of remembering experiences, even for a year or more (Bauer & Larkina, 2014; Morris et al., 2010). Mice and monkeys also forget their early life, as rapid neuron growth disrupts the circuits that stored old memories (Akers et al., 2014). The brain areas underlying memory, such as the hippocampus and frontal lobes, continue to mature into adolescence (Bauer, 2007).

Apart from constructed memories based on photos and family stories, we consciously recall little from our early years, yet our brain was processing and storing information. While finishing her doctoral work in psychology, Carolyn Rovee-Collier observed nonverbal infant memory in action. Her 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 can learn. 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. 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 (FIGURE 4.8).

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 not learn (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 remember.

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

Somewhere on your life journey, you became conscious. When was that? Jean Piaget [pee-ah-ZHAY] was a pioneering developmental psychologist who spent his life searching for the answers to such questions. He studied children’s cognitive development—all the mental activities associated with thinking, knowing, remembering, and communicating. 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. Such accidental discoveries are among the fruits of psychological science.

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 careful observations, we now understand that children reason differently than adults, in “wildly illogical ways about problems whose solutions are self-evident to adults” (Brainerd, 1996).

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 was that our intellectual progression reflects 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.

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. Many people whose schema of marriage was a union between a man and a woman have now accommodated same-sex marriage, with a broadened marriage concept.

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. In Piaget’s view, cognitive development consisted of four major stages—sensorimotor, preoperational, concrete operational, and formal operational.

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.

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 (FIGURE 4.9). Within another month or two, the infant will look for it even after being restrained for several seconds.

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So does object permanence in fact blossom suddenly at 8 months, much as tulips blossom in spring? Today’s researchers 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. Preschoolers think like little scientists. They test ideas, make causal inferences, and learn from statistical patterns (Gopnik et al., 2015). Consider these simple experiments:

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—able to represent things with words and images but 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 (FIGURE 4.11).

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PRETEND PLAY A child who can perform mental operations can think in symbols and enjoy pretend play. 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. Although Piaget did not view the stage transitions as abrupt, 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. They are like the person who, when asked by someone across a river, “How do I get to the other side?” answered “You are on the other side.” 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.”

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). Perhaps you can recall asking someone to guess a simple tune such as “Happy Birthday” as you clapped or tapped it out. With the tune in your head, it seemed so obvious! But you suffered the egocentric curse of knowledge, by assuming that what was in your head was also in someone else’s.

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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 (Premack & Woodruff, 1978). The theory of mind concept was first used to describe chimpanzees’ seeming ability to read others’ intentions. Later, psychologists aimed to identify when humans develop a theory of mind.

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. Being able to take another’s perspective enables relationships. Children who have an advanced ability to understand others’ minds tend to be more popular (Slaughter et al., 2015).

Between about ages 3 and 4½, children worldwide come to realize that others may hold false beliefs (Callaghan et al., 2005; Rubio-Fernández & Geurtz, 2013; Sabbagh et al., 2006). Jennifer Jenkins and Janet Astington (1996) showed Toronto children a Band-Aid 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 about age 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:

Piaget believed that during the concrete operational stage, children become able to comprehend mathematical transformations and conservation. When my [DM’s] 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, 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.

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

Formal operational thinkers have no trouble answering correctly. But neither do most 7-year-olds (Suppes, 1982). TABLE 4.1 below summarizes the four stages in Piaget’s theory.

An Alternative Viewpoint: Lev Vygotsky and the Social Child

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As Piaget was forming his theory of cognitive development, Russian psychologist Lev Vygotsky 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. The self-talk advantage is not limited to children. Adults who motivate themselves using self-talk (“You can do it!”) also experience better performance (Kross et al., 2014).

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 social environment. 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 scaffold from 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).

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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 his being 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 see 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.

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).

Autism Spectrum Disorder

4-6 What is autism spectrum disorder?

Diagnoses of autism spectrum disorder (ASD), a disorder marked by social deficiencies and repetitive behaviors, have been increasing. Once believed to affect 1 in 2500 children (and referred to simply as autism), ASD now gets diagnosed in 1 in 68 American children by age 8. But the reported rates vary by place, with New Jersey having four times the reported prevalence of Alabama, while Britain’s children have a 1 in 100 rate, and South Korea’s 1 in 38 (CDC, 2014; Kim et al., 2011; NAS, 2011). The increase in ASD diagnoses has been offset by a decrease in the number of children with a “cognitive disability” or “learning disability,” which suggests a relabeling of children’s disorders (Gernsbacher et al., 2005; Grinker, 2007; Shattuck, 2006).

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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. From age 2 months on, as other children spend more and more time looking into others’ eyes, those who later develop ASD do so less and less (Jones & Klin, 2013). People with ASD are said to have an impaired theory of mind (Rajendran & Mitchell, 2007; Senju et al., 2009). Mind reading that most of us find intuitive (Is that face conveying a smirk or a sneer?) is difficult for those with ASD. They have difficulty inferring and remembering others’ thoughts and feelings, learning that twinkling eyes mean happiness or mischief, and appreciating that playmates and parents might view things differently (Boucher et al., 2012; Frith & Frith, 2001). Partly for such reasons, a national survey of parents and school staff reported that 46 percent of adolescents with ASD had suffered the taunts and torments of bullying—about four times the 11 percent rate for other children (Sterzing et al., 2012). In hopes of a cure, desperate parents have sometimes subjected children to dubious therapies (Lilienfeld et al. 2014; Shute, 2010).

ASD has differing levels of severity. Some (those diagnosed with what used to be called Asperger syndrome) generally function at a high level. They have normal intelligence, often accompanied by exceptional skill or talent in a specific area, but deficient social and communication skills and a tendency to become distracted by irrelevant stimuli (Remington et al., 2009). Those at the spectrum’s lower end struggle to use language at all.

Biological factors, including genetic influences and abnormal brain development, contribute to ASD (State & Šestan, 2012). Studies suggest that the prenatal environment matters, especially when altered by maternal infection and inflammation, psychiatric drug use, or stress hormones (NIH, 2013; Wang, 2014). Childhood MMR vaccinations do not contribute to ASD (Demicheli et al., 2012; DeStefano et al., 2013). 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.

Both boys and girls can have ASD, but there are large gender differences. ASD afflicts about four boys for every girl. Children for whom amniotic fluid analyses indicated high prenatal testosterone develop more masculine and ASD-related traits (Auyeung et al., 2009). Psychologist Simon Baron-Cohen (2008, 2009) argues that ASD represents an “extreme male brain.” Girls are naturally predisposed to be “empathizers,” he contends. They tend to be better at reading facial expressions and gestures, though less so if given testosterone (van Honk et al., 2011). And, although the sexes overlap, he believes boys are more often “systemizers”—better at understanding things according to rules or laws, as in mathematical and mechanical systems.

Numerous studies verify biology’s influence. If one identical twin is diagnosed with ASD, the chances are 50 to 70 percent that the co-twin will be as well (Lichtenstein et al., 2010; Sebat et al., 2007). A younger sibling of a child with ASD also is at a heightened risk (Sutcliffe, 2008). No one “autism gene” accounts for the disorder. Rather, many genes—with more than 200 identified so far—appear to contribute (Gaugler et al., 2014; Heil & Schaaf, 2013). 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).

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Researchers are also sleuthing ASD’s telltale signs in the brain’s structure. Several studies have revealed underconnectivity—fewer-than-normal fiber tracts connecting the front of the brain to the back (Ecker et al., 2012; Just et al., 2012; Wolff et al., 2012). With underconnectivity, there is less of the whole-brain synchrony that, for example, integrates visual and emotional information.

Biology’s role in ASD also appears in the brain’s functioning. 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 exploring and debating this idea that the brains of people with ASD have “broken mirrors” (Gallese et al., 2011). And they are exploring whether treatment with oxytocin, the hormone that promotes social bonding, might improve social behavior in those with ASD (Gordon et al., 2013; Lange & McDougle, 2013).

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 (FIGURE 4.12). After the boy leaves for school, the characters come to life and have experiences that lead them to display various emotions (see 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 now equaled that of children without ASD.

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4-7 How do parent-infant attachment bonds form?

From birth, babies are normally very 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.

Human Bonding

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. 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. But an accidental finding overturned this explanation.

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 cheesecloth baby blanket (Harlow et al., 1971). Then came a surprise: When their soft 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 (FIGURE 4.13). 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.

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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). 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.

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, reenact family traditions. They prefer to eat familiar foods, live in the same familiar neighborhood, attend school with the same old friends. Familiarity is a safety signal. Familiarity breeds content.

Attachment Differences

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4-8 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 (FIGURE 4.14).

Although remembered by some as the researcher who tortured helpless monkeys, Harry Harlow defended his methods: “Remember, for every mistreated monkey there exist a million mistreated children,” he said, expressing the hope that his research would sensitize people to child abuse and neglect. “No one who knows Harry’s work could ever argue that babies do fine without companionship, that a caring mother doesn’t matter,” noted Harlow biographer Deborah Blum (2002, p. 307). “And since we . . . didn’t fully believe that before Harry Harlow came along, then perhaps we needed—just once—to be smacked really hard with that truth so that we could never again doubt.”

So, caring parents matter. 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? Twin and developmental studies reveal that heredity affects temperament, and temperament affects attachment style (Picardi et al., 2011; Raby et al., 2012).

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). 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; Roque et al., 2012). One form of a gene that regulates the neurotransmitter serotonin predisposes a fearful temperament and, in combination with unsupportive caregiving, an emotionally reactive child (Raby et al., 2012).

Temperament differences typically persist. Consider:

Parenting studies that neglect such inborn differences, noted Judith Harris (1998), do the equivalent of “comparing foxhounds reared in kennels with poodles reared in apartments.” To separate the effects of nature and nurture on attachment, we would need to vary parenting while controlling temperament. (Pause and think: If you were the researcher, how might you have done this?)

Dutch researcher Dymphna van den Boom’s solution was to randomly assign 100 temperamentally difficult 6- to 9-month-olds to either an experimental group, in which mothers received personal training in sensitive responding, or to a control group, in which they did not. At 12 months of age, 68 percent of the experimental group were rated securely attached, as were only 28 percent of the control group infants. Other studies have confirmed that intervention programs can increase parental sensitivity and, to a lesser extent, infant attachment security (Bakermans-Kranenburg et al., 2003; Van Zeijl et al., 2006).

As many of these examples indicate, researchers have more often studied mother care than father care, but fathers are more than just mobile sperm banks. Despite the widespread attitude that “fathering a child” means impregnating, and “mothering” means nurturing, nearly 100 studies worldwide have shown that a father’s love and acceptance are comparable with a mother’s love in predicting an offspring’s health and well-being (Rohner & Veneziano, 2001; see also TABLE 4.2). In one mammoth British study following 7259 children from birth to adulthood, those whose fathers were most involved in parenting (through outings, reading to them, and taking an interest in their education) tended to achieve more in school, even after controlling for other factors such as parental education and family wealth (Flouri & Buchanan, 2004). Fathers matter.

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Children’s anxiety over separation from parents peaks at around 13 months, then gradually declines (FIGURE 4.15). This happens whether they live with one parent or two, are cared for at home or in a day-care center, live in North America, Guatemala, or the Kalahari Desert. Does this mean our need for and love of others also fades away? Hardly. Our capacity for love grows, and our pleasure in touching and holding those we love never ceases.

ATTACHMENT STYLES AND LATER RELATIONSHIPS Developmental theorist Erik Erikson (1902-1994), working with his wife, Joan Erikson (1902–1997), believed that securely attached children approach life with a sense of basic trust—a sense that the world is predictable and reliable. He attributed basic trust not to environment or inborn temperament, but to early parenting. He theorized that infants blessed with sensitive, loving caregivers form a lifelong attitude of trust rather than fear.

Many researchers now believe that our early attachments form the foundation for our adult relationships (Birnbaum et al., 2006; Fraley et al., 2013). People who report secure relationships with their parents tend to enjoy secure friendships (Gorrese & Ruggieri, 2012). When leaving home to attend college—another kind of “strange situation”—those securely attached to parents tend to adjust well (Mattanah et al., 2011). Secure, responsive mothers tend to have children who flourish socially and academically (Raby et al., 2014).

Feeling insecurely attached to others may take either of two main forms (Fraley et al., 2011). With insecure-anxious attachment, people constantly crave acceptance but remain alert to signs of rejection. With insecure-avoidant attachment, people experience discomfort when getting close to others and use avoidant strategies to maintain distance from others. In one study of over 90,000 adults in 81 countries, anxious attachment peaked in young adulthood, whereas avoidant attachment was highest among older adults (Chopik & Edelstein, 2014). As we journey through life and gather many relationship experiences, we tend to become less alert to signs of rejection and prefer independence.

Adult attachment styles affect relationships with romantic partners and one’s own children (Hadden et al., 2014; Jones et al., 2015). An anxious attachment style hinders social connections. An avoidant style decreases commitment and increases conflict (DeWall et al., 2011; Li & Chan, 2012). But say this for those (nearly half of all people) who exhibit wary, insecure attachments: Anxious or avoidant tendencies have helped our groups detect or escape dangers (Ein-Dor et al., 2010).

Deprivation of Attachment

4-9 How does childhood neglect or abuse affect children’s attachments?

If secure attachment fosters social trust, what happens when circumstances prevent a child from forming attachments? In all of psychology, there is no sadder research literature. Babies locked away at home under conditions of abuse or extreme neglect are often withdrawn, frightened, even speechless. The same is true of those raised in institutions without the stimulation and attention of a regular caregiver, as was tragically illustrated during the 1970s and 1980s in Romania. Having decided that economic growth for his impoverished country required more human capital, Nicolae Ceauşescu, Romania’s Communist dictator, outlawed contraception, forbade abortion, and taxed families with fewer than five children. The birthrate skyrocketed. But unable to afford the children they had been coerced into having, many families abandoned them to government-run orphanages with untrained and overworked staff. Child-to-caregiver ratios often were 15 to 1, so the children were deprived of healthy attachments with at least one adult. When tested after Ceauşescu’s 1989 execution, these socially deprived children had lower intelligence scores, reduced brain development, abnormal stress responses, and double the 20 percent rate of anxiety symptoms found in children assigned to quality foster care settings (Bick et al., 2015; McLaughlin et al., 2015; Nelson et al., 2009, 2014). Dozens of other studies across 19 countries have confirmed that orphaned children tend to fare better on later intelligence tests if raised in family homes. This is especially so for those placed at an early age (van IJzendoorn et al., 2008).

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Most children growing up under adversity (as did the surviving children of the Holocaust) are resilient; they withstand the trauma and become well-adjusted adults (Helmreich, 1992; Masten, 2001). So do most victims of childhood sexual abuse, noted Harvard researcher Susan Clancy (2010), while emphasizing that using children for sex is revolting and never the victim’s fault. Indeed, hardship short of trauma often boosts mental toughness (Seery, 2011). And though growing up poor puts children at risk for some social pathologies, growing up rich puts them at risk for other pathologies. Affluent children are at elevated risk for substance abuse, eating disorders, anxiety, and depression (Lund & Dearing, 2012; Luthar et al., 2013). So when you face adversity, consider the possible silver lining.

But those who experience enduring abuse don’t bounce back so readily. The Harlows’ monkeys raised in total isolation, without even an artificial mother, bore lifelong scars. As adults, when placed with other monkeys their age, they either cowered in fright or lashed out in aggression. When they reached sexual maturity, most were incapable of mating. If artificially impregnated, females often were neglectful, abusive, even murderous toward their first-born. Another primate experiment confirmed the abuse-breeds-abuse phenomenon in rhesus monkeys: 9 of 16 females who had been abused by their mothers became abusive parents, as did no female raised by a nonabusive mother (Maestripieri, 2005).

In humans, too, the unloved may become the unloving. Most abusive parents—and many condemned murderers—have reported being neglected or battered as children (Kempe & Kempe, 1978; Lewis et al., 1988). Some 30 percent of people who have been abused later abuse their children—a rate lower than that found in the primate study, but four times the U.S. national rate of child abuse (Dumont et al., 2007; Kaufman & Zigler, 1987).

Although most abused children do not later become violent criminals or abusive parents, extreme early trauma may nevertheless leave footprints on the brain. Like battle-stressed soldiers, abused children’s brains respond to angry faces with heightened activity in threat-detecting areas (McCrory et al., 2011). In conflict-plagued homes, even sleeping infants’ brains show heightened reactivity to hearing angry speech (Graham et al., 2013). As adults, these children exhibit stronger startle responses (Jovanovic et al., 2009). If repeatedly threatened and attacked while young, normally placid golden hamsters grow up to be cowards when caged with same-sized hamsters, or bullies when caged with weaker ones (Ferris, 1996). Such animals show changes in the brain chemical serotonin, which calms aggressive impulses. A similarly sluggish serotonin response has been found in abused children who become aggressive teens and adults. By sensitizing the stress response system, early stress can permanently heighten reactions to later stress and increase stress-related disease (Fagundes & Way, 2014; van Zuiden et al., 2012; Wei et al., 2012). Child abuse also leaves epigenetic marks—chemical tags—that can alter the normal gene expression (McGowan et al., 2009; Romens et al., 2015).

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Such findings help explain why young children who have survived severe or prolonged physical abuse, childhood sexual abuse, bullying, or wartime atrocities are at increased risk for health problems, psychological disorders, substance abuse, and criminality (Lereya et al., 2015; Nanni et al., 2012; Trickett et al., 2011; Whitelock et al., 2013; Wolke et al., 2013). In one national study of 43,093 adults, 8 percent reported experiencing physical abuse at least fairly often before age 18 (Sugaya et al., 2012). Among these, 84 percent had experienced at least one psychiatric disorder. Moreover, the greater the abuse, the greater the odds of anxiety, depression, and substance use disorder, and of attempted suicide. Abuse victims are at considerable risk for depression if they carry a gene variation that spurs stress-hormone production (Bradley et al., 2008). As we will see again and again, behavior and emotion arise from a particular environment interacting with particular genes. Nature and nurture matter.

We adults also suffer when our attachment bonds are severed. Whether through death or separation, a break produces a predictable sequence. Agitated preoccupation with the lost partner is followed by deep sadness and, eventually, the beginnings of emotional detachment and a return to normal living (Hazan & Shaver, 1994). Newly separated couples who have long ago ceased feeling affection are sometimes surprised at their desire to be near the former partner. Detaching is a process, not an event.

Parenting Styles

4-10 What are three parenting styles, and how do children’s traits relate to them?

Some parents spank, some reason. Some are strict, some are lax. Some show little affection, some liberally hug and kiss. Do such differences in parenting styles affect children?

The most heavily researched aspect of parenting has been how, and to what extent, parents seek to control their children. Investigators have identified three parenting styles:

Too hard, too soft, and just right, these styles have been called, especially by pioneering researcher Diana Baumrind and her followers. Research indicates that children with the highest self-esteem, self-reliance, and social competence usually have warm, concerned, authoritative parents (Baumrind, 1996, 2013; Buri et al., 1988; Coopersmith, 1967). Those with authoritarian parents tend to have less social skill and self-esteem, and those with permissive parents tend to be more aggressive and immature. The participants in most studies have been middle-class White families, and some critics suggest that effective parenting may vary by culture. Yet studies with families in more than 200 cultures worldwide have confirmed the social and academic correlates of loving and authoritative parenting (Rohner & Veneziano, 2001; Sorkhabi, 2005; Steinberg & Morris, 2001). For example, two studies of thousands living in Germany found that those whose parents had maintained a curfew exhibited better adjustment and greater achievements in young adulthood than did those with permissive parents (Haase et al., 2008).

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A word of caution: The association between certain parenting styles (being firm but open) and certain childhood outcomes (social competence) is correlational. Correlation is not causation. Perhaps you can imagine possible explanations for this parenting-competence link.

Parents who struggle with conflicting advice should also remember that all advice reflects the advice-giver’s values. For parents who prize unquestioning obedience or whose children live in dangerous environments, an authoritarian style may have the desired effect. For those who value children’s sociability and self-reliance, authoritative firm-but-open parenting is advisable.

CULTURE AND CHILD RAISING Child-raising practices reflect not only individual values, but also cultural values, which vary across time and place. Should children be independent or obedient? If you live in a Westernized culture, you likely prefer independence. “You are responsible for yourself,” Western families and schools tell their children. “Follow your conscience. Be true to yourself. Discover your gifts. Think through your personal needs.”

In recent years, some Western parents have gone further, telling their children, “You are more special than other children” (Brummelman et al., 2015). (Not surprisingly, these puffed-up children tend to have inflated self-views years later.) A half-century ago and more, however, Western cultural values placed greater priority on obedience, respect, and sensitivity to others (Alwin, 1990; Remley, 1988). “Be true to your traditions,” parents then taught their children. “Be loyal to your heritage and country. Show respect toward your parents and other superiors.” Cultures can change.

Children across time and place have thrived under various child-raising systems. Many Americans now give children their own bedrooms and entrust them to day care. Upper-class British parents traditionally handed off routine caregiving to nannies, then sent their 10-year-olds away to boarding school. These children generally grew up to be pillars of British society.

Many Asian and African cultures place less value on independence and more on a strong sense of family self—a feeling that what shames the child shames the family, and what brings honor to the family brings honor to the self. These cultures also value emotional closeness, and infants and toddlers may sleep with their mothers and spend their days close to a family member (Morelli et al., 1992; Whiting & Edwards, 1988). In the African Gusii society, babies have nursed freely but spent most of the day on their mother’s back—with lots of body contact but little face-to-face and language interaction. When the mother becomes pregnant again, the toddler is weaned and handed over to someone else, often an older sibling. Westerners may wonder about the negative effects of this lack of verbal interaction, but then the African Gusii may in turn wonder about Western mothers pushing their babies around in strollers and leaving them in playpens (Small, 1997).

Such diversity in child raising cautions us against presuming that our culture’s way is the only way to raise children successfully. One thing is certain, however: Whatever our culture, the investment in raising a child buys many years not only of joy and love but also of worry and irritation. In a national Gallup survey, adults with children under 18 at home were more likely than other adults to report smiling and laughing “a lot yesterday”—but also to have experienced stress “a lot of the day yesterday” (Witters, 2014). Yet for most people who become parents, a child is one’s biological and social legacy—one’s personal investment in the human future. To paraphrase psychiatrist Carl Jung, we reach backward into our parents and forward into our children, and through their children into a future we will never see, but about which we must therefore care.

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Learning Objectives

Test Yourself by taking a moment to answer each of these Learning Objective Questions (repeated here from within the chapter). Research suggests that trying to answer these questions on your own will improve your long-term memory of the concepts (McDaniel et al., 2009).

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Terms and Concepts to Remember

Test yourself on these terms.

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Experience the Testing Effect

Test yourself repeatedly throughout your studies. This will not only help you figure out what you know and don’t know; the testing itself will help you learn and remember the information more effectively thanks to the testing effect.

Question 4.6

Question 4.7

Question 4.8

Question 4.9

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Question 4.10

Question 4.11

Question 4.12

Question 4.13

Use to create your personalized study plan, which will direct you to the resources that will help you most in .