In their first two years, infants progress from reactive pain and pleasure to complex patterns of social awareness (see At About This Time), a movement from reflexive emotions to learned and then thoughtful ones (Panksepp & Watt, 2011). Infant emotions arise more from basic impulses than from the cortex, so speedy, uncensored reactions—crying, startling, laughing, raging—are common.

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As always, culture and experience influence the norms of development. This is especially true for emotional development after the first eight months.

At first there is pleasure and pain. Both are evident throughout infancy, even throughout life, but the triggers, reasons, and expressions change with development, and many new emotions appear.

AT BIRTH Newborns are happy and relaxed when fed and drifting off to sleep. They cry when they are hurt or hungry, tired or frightened (as by a loud noise or a sudden loss of support). Some infants have bouts of uncontrollable crying, called colic, probably the result of immature digestion; some have reflux, probably the result of immature swallowing. About 20 percent of babies cry “excessively,” defined as more than three hours a day, more than three days a week, more than three weeks (J. S. Kim, 2011).

Curiosity is also present, although briefly, as sleep and hunger overtake almost every other reaction. Even a crying baby can suddenly grow quiet, when sucking and food overcome the emotion.

SMILING AND LAUGHING Soon, additional emotions become recognizable. Happiness is expressed by the social smile, evoked by a human face at about 6 weeks for full-term babies, a few weeks later for preterm infants.

Infants worldwide express social joy, even laughter, between 2 and 4 months (Konner, 2007; Lewis, 2010). Laughter builds as curiosity does; a typical 6-month-old laughs loudly upon discovering new things, particularly social experiences that balance familiarity and surprise, such as Daddy making a funny face. They prefer looking at happy faces rather than sad ones, even if the happy faces are not looking at them (Kim & Johnson, 2013).

ANGER AND SADNESS The positive emotions of joy and contentment are joined by negative emotions. Obvious anger appears by 6 months, usually triggered by frustration, such as when infants are prevented from moving or grabbing. Infants hate to be strapped in, caged in, closed in, or even just held in place when they want to explore.

In infancy, anger is generally a healthy response to frustration, unlike sadness, which also appears in the first months. Sadness indicates withdrawal and is accompanied by a greater increase in the body’s production of cortisol.

Since sadness produces physiological stress (measured by cortisol levels), sorrow negatively impacts the infant. All social emotions, particularly sadness and fear, probably shape the brain (Fries & Pollak, 2007; Johnson, 2011). As you learned in Chapter 3, experience matters. Sad and angry infants whose mothers are depressed become fearful toddlers (Dix & Yan, 2014). Too much sadness early in life correlates with depression later on.

FEAR Fear in response to some person, thing, or situation (not just being startled in surprise) is evident at about 9 months and soon becomes more frequent and obvious. Two kinds of social fear are typical:

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Separation anxiety is normal at age 1, intensifies by age 2, and usually subsides after that. Fear of separation interferes with infant sleep. For example, infants who fall asleep next to familiar people may wake up frightened if they are alone (Sadeh et al., 2010). The solution is not necessarily to sleep with the baby, but neither is it to ignore the child’s natural fear of separation.

Some babies are comforted by a “transitional object,” such as a teddy bear or blanket, beside them as they transition from sleeping in their parents’ arms to sleeping alone. Music, a night light, or an open door may ease the fear.

Transitional objects are not pathological; they are the infant’s way of coping with anxiety. However, if separation anxiety remains strong after age 3 and impairs the child’s ability to leave home, go to school, or play with friends, it is considered an emotional disorder. Separation anxiety as a disorder can be diagnosed up to age 18 (American Psychiatric Association, 2013); some clinicians diagnose it in adults as well (Bögels et al., 2013).

Separation anxiety may be apparent outside the home. Strangers—especially those who do not look or move like familiar caregivers—merit stares, not smiles, at age 1. This is a good sign: Infant memory is active and engaged. Fear of strangers is normative, which means that every toddler typically manifests it, but genes and parents make it stronger (as when the child cries and hides) or weaker (with a wary look). Children whose parents are themselves anxious are likely to fear new people throughout childhood (Brooker et al., 2013).

Many normal 1-year-olds fear anything unexpected, from the flush of the toilet to the pop of a jack-in-the-box, from closing elevator doors to the tail-wagging approach of a dog. With repeated experience and reassurance, older infants might enjoy flushing the toilet (again and again) or calling the dog (crying if the dog does not come). Note the transition from instinct to learning to thought (Panksepp & Watt, 2011).

Emotions take on new strength during toddlerhood, as both memory and mobility advance (Izard, 2009). For example, throughout the second year and beyond, anger and fear become less frequent but more focused, targeted toward infuriating or terrifying experiences. Similarly, laughing and crying are louder and more discriminating. This is the familiar path from sensation to perception to cognition.

The new strength of emotions is apparent in temper tantrums. Toddlers are famous for fury. When something angers them, they might yell, scream, cry, hit, and throw themselves on the floor. Logic is beyond them; if adults respond with anger or teasing, that makes it worse.

One child was angry at her feet and said she did not want them. When a parent offered to get a scissors and cut them off, a new wail of tantrum erupted. With temper tantrums, soon sadness comes to the fore, at which time comfort—rather than acquiescence or punishment—is helpful (Green et al., 2011).

SOCIAL AWARENESS Temper can be seen as an expression of selfhood. So can new toddler emotions: pride, shame, jealousy, embarrassment, disgust, and guilt. These emotions require social awareness, which typically emerges from family interactions. For instance, in a study of infant jealousy, when mothers deliberately paid attention to another infant, babies moved closer to their mothers, bidding for attention. Brain activity also registered social awareness (Mize et al., 2014).

Culture is crucial here, with independence a value in some families but not in others. Many North American parents encourage toddler pride (saying, “You did it yourself”—even when that is untrue), but Asian families typically cultivate modesty and shame. Such differences may still be apparent in adult personality and judgment.

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Disgust is also strongly influenced by other people. According to a study that involved children of various ages, many 18-month-olds (but not younger infants) express disgust at touching a dead animal. None, however, were disgusted when a teenager cursed at an elderly person—something that parents and older children often find disgusting (Stevenson et al., 2010).

SELF-AWARENESS In addition to social awareness, another foundation for emotional growth is self-awareness, the realization that one’s body, mind, and activities are distinct from those of other people (Kopp, 2011). Closely following the new mobility that results from walking is an emerging sense of “me” and “mine” that leads the infant to develop a new consciousness of self and others at about age 1.

In a classic experiment (Lewis & Brooks, 1978), 9- to 24-month-olds looked into a mirror after a dot of rouge had been surreptitiously put on their noses. If they reacted by touching the red dot on their noses, that meant they knew the mirror reflected their own faces. None of the babies younger than 12 months did that, although they sometimes smiled and touched the dot on the “other” baby in the mirror.

However, at some time between 15 and 24 months, babies become self-aware, touching their noses with curiosity and puzzlement. Self-recognition in the mirror/rouge test (and in photographs) usually emerges at about 18 months, along with two other advances: pretending and using first-person pronouns (I, me, mine, myself, my) (Lewis, 2010).

As another scholar explains it, “an explicit and hence reflective conception of the self is apparent at the early stage of language acquisition at around the same age that infants begin to recognize themselves in mirrors” (Rochat, 2013, p. 388). This is yet another example of the interplay of all the infant abilities—walking, talking, and emotional self-understanding work together to make the 18-month-old a quite different person from the 8-month-old.

Brain maturation is involved in the developments just described because every reaction begins in the brain (Johnson, 2011). Experience produces connections between neurons and emotions.

Links between expressed emotions and brain growth are complex and thus difficult to assess and describe with precision (Lewis, 2010). Compared with the emotions of adults, discrete emotions—the difference between fear and excitement, for instance—during early infancy are murky and unpredictable.

The growth of synapses and dendrites is a likely explanation for the gradual refinement and expression of each emotion, the result of past experiences and ongoing maturation. Already by 6 months, an infant’s brain patterns and stress hormones seem affected by caregiver responsiveness (Enlow et al., 2014).

GROWTH OF THE BRAIN Many specific aspects of brain development support social emotions (Lloyd-Fox et al., 2009). For instance, the social smile and laughter appear as the cortex matures (Konner, 2010). The same is probably true for fear, self-awareness, and anger. The brains of 8-month-olds respond to other people who look or act afraid, and that probably enhances the infant’s own expression of fear (Missana et al., 2014).

Cultural differences become encoded in the infant brain, called “a cultural sponge” by one group of scientists (Ambady & Bharucha, 2009, p. 342). It is difficult to measure exactly how infant brains are molded by their context, in part because few parents give permission for scanning the brains of their normally developing infants. However, in one study (Zhu et al., 2007) adults—half born in the United States and half in China—were asked whether certain adjectives applied to them. For both groups, a particular area of the brain (the medial prefrontal cortex) was activated by that question. Then they were asked whether the same adjectives applied to their mothers. That medial prefrontal cortex was activated for the Chinese participants, but not for the U.S. ones.

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Researchers consider this finding to be “neuroimaging evidence that culture shapes the functional anatomy of self-representation” (Zhu et al., 2007, p. 1310). They speculate that brain activation occurs because the Chinese participants learned, as babies, that they are closely aligned with their mothers, whereas the U.S. participants learned to be independent.

Beyond culture, an infant’s brain activity interacts with caregiver responses, probably in the first months of life as well as through the years of childhood (E. Nelson et al., 2014). Highly reactive 15-month-olds (who were quick to cry) with wonderfully responsive caregivers (not hostile or neglectful) became less fearful, less angry, and so on (Ursache et al., 2013).

By age 4, they could regulate their emotions, no longer bursting into tears at any distress. Presumably they had developed neurological links between brain excitement and emotional response, so their excitement was connected to thought. However, highly reactive toddlers whose caregivers were less responsive were often overwhelmed by their emotions later on (Ursache et al., 2013). Differential susceptibility is apparent: Innate reactions and caregiver actions together sculpt the brain.

LEARNING ABOUT OTHERS The tentative social smiles of 2-month-old infants to any face soon become quick and full smiles when they see their familiar caregivers. This occurs because, with repeated experience, the neurons that fire together become more closely and quickly connected to each other (via dendrites).

Social preferences form in the early months, connected not only with a person’s face but also with voice, touch, and smell. Early social awareness is one reason adopted children ideally join their new parents in the first days of life (a marked change from 100 years ago, when adoptions began after age 1).

Social awareness is also a reason to respect an infant’s reaction to a babysitter: If a 6-month-old screams and clings to the parent when the sitter arrives, another babysitter probably needs to be found. (Do not confuse this reaction with separation anxiety at 12 months—a normal, expected reaction.)

Every experience that a person has—especially in the early days and months—activates and prunes neurons, firing patterns from one axon to a dendrite reflect past learning.

As illustrated in Visualizing Development in Chapter 3, p. 95, this was first shown dramatically with baby mice: Some were licked and nuzzled by their mothers almost constantly, and some were neglected. A mother mouse’s licking of her newborn babies reduced methylation of a gene (Nr3c1), which allowed more serotonin (a neurotransmitter) to be released by the hypothalamus (a region of the brain discussed in Chapter 5).

Serotonin not only increased momentary pleasure (mice love being licked) but also started a chain of epigenetic responses to reduce cortisol from many parts of the brain and body, including the adrenal glands. The effects on both brain and behavior are lifelong for mice and probably for humans as well.

For many humans, social anxiety is stronger than any other anxiety. Certainly to some extent this is genetic. But epigenetic research finds environmental influences are important as well. This was clearly shown in a longitudinal study of 1,300 adolescents (twins and siblings): Their genetic tendency toward anxiety was evident at every age, but life events affected how strong that anxiety was felt (Zavos et al., 2012).

A smaller study likewise found that if the infant of an anxious biological mother is raised by a responsive adoptive mother who is not anxious, the inherited anxiety does not materialize (Natsuaki et al., 2013).

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Parents need to be comforting (as with the nuzzled baby mice) but not overprotective. Fearful mothers tend to raise fearful children, but fathers who offer their infants exciting but not dangerous challenges (such as a game of chase, crawling on the floor) reduce later anxiety (Majdandži´c et al., 2013).

STRESS Emotions are connected to brain activity and hormones; they are affected by genes, past experiences, and additional hormones and neurotransmitters. Many of the specifics are not yet understood, but one link is clear: Excessive fear and stress harms the developing brain.

The specific mechanism seems to be that normally “the mother’s presence acts as a social buffer,” keeping cortisol levels low and thus fear at bay. However, if that does not occur, the brain develops more rapidly than normal. In that case, a child who seems adultlike in some emotions later becomes impaired because the parts of the brain that respond to emotions developed too quickly (Tottenham, 2014).

Brain scans of children who were maltreated in infancy show abnormal responses to stress, anger, and other emotions later on, including to photographs of frightened people. Some children seem resilient, but many areas of the brain (the prefrontal cortex, discussed in Chapter 3, and the hypothalamus, amygdala, HPA axis, and hippocampus, which will be explained in later chapters) are affected by abuse, especially if the maltreatment begins before age 2 (Bernard et al., 2014; Cicchetti, 2013a).

Since early caregiving affects the brain lifelong, caregivers should be consistent and reassuring. This is not always easy. Remember that some infants cry inconsolably in the early weeks. One researcher notes:

An infant’s crying has 2 possible consequences: it may elicit tenderness and desire to soothe, or helplessness and rage. It can be a signal that encourages attachment or one that jeopardizes the early relationship by triggering depression and, in some cases, even neglect or abuse.

[J. S. Kim, 2011, p. 229]

Sometimes mothers are blamed, or blame themselves, when an infant cries. This attitude is not helpful: A mother who feels guilty or incompetent may become angry at her baby, which leads to unresponsive parenting, an unhappy child, and then hostile interactions. (Presumably the results would be the same if the father, or grandmother, were the primary caregiver, although extensive research on those infant–caregiver relationships has not yet been published.) Years later, first-grade classmates and teachers are likely to consider children of unresponsive mothers disruptive and aggressive (Lorber & Egeland, 2011).

But the opposite may occur if early crying produces solicitous parenting. Then, when the baby outgrows the crying, the parent–child bond may be exceptionally strong.

A study of colicky babies found both reactions in the parents (Landgren et al., 2012). One mother said:

There were moments when, both me and my husband … when she was apoplectic and howling so much that I almost got this thought, ‘now I’ll take a pillow and put over her face just until she quietens down, until the screaming stops.’

By contrast, another mother said

In some way, it made me stronger, and made my relationship with my son stronger … Because I felt that he had no one else but me. ‘If I can´t manage, no one can.’ So I had to cope.

Remember from Chapter 3 that cross-modal perception occurs in infancy, making synesthesia more common than later on. A caregiver’s smell and voice may evoke a vision of that person, for instance, or a sound may be connected with a shape. For example, when 4-month-old infants hear words that seem more staccato—such as “kiki”—they are more likely to look at an angular shape than a round one (Ozturk et al., 2013).

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The tendency of one part of the brain to activate another may also occur for emotions. An infant’s cry can be triggered by pain, fear, tiredness, surprise, or excitement; laughter can turn to tears. Infant emotions may erupt, increase, or disappear for unknown reasons (Camras & Shutter, 2010). Brain immaturity is a likely explanation.

Temperament is defined as the “biologically based core of individual differences in style of approach and response to the environment that is stable across time and situations” (van den Akker et al., 2010, p. 485). “Biologically based” means that these traits originate with nature, not nurture. Confirmation that temperament arises from the inborn brain comes from an analysis of the tone, duration, and intensity of infant cries after the first inoculation, before much experience outside the womb. Cry variations at this very early stage correlate with later temperament (Jong et al., 2010).

Temperament is not the same as personality, although temperamental inclinations may lead to personality differences. Generally, personality traits (e.g., honesty and humility) are learned, whereas temperamental traits (e.g., shyness and aggression) are genetic. Of course, for every trait, nature and nurture interact.

In laboratory studies of temperament, infants are exposed to events that are frightening or attractive. Four-month-olds might see spinning mobiles or hear unusual sounds. Older babies might confront a noisy, moving robot or a clown who quickly moves close to them. During such experiences, some children laugh, some cry, others are quiet, and still others exhibit a combination of these reactions.

Generally, three dimensions of temperament are found (Hirvonen et al., 2013; van den Akker et al., 2010; Degnan et al., 2011), each of which affects later personality and achievement.

Each of these dimensions is associated with distinctive brain patterns as well as behavior, with the last of these (exuberance versus shyness) most strongly traced to genes (Wolfe et al., 2014). Of course, all temperament traits are thought to be biologically based with a genetic component, but the distinction between temperament (biology) and personality (learned) is clearer on paper than in people. Social scientists sometimes interpret the data in opposite ways, as you will now see.

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