Lifespan Development. Tara L. Kuther

cries influence infants’ capacity for self-regulation and responses to stress. Babies who receive more responsive and immediate caregiving when distressed show lower rates of persistent crying, spend more time in happy and calm states, and cry less overall as they approach their first birthday (Axia & Weisner, 2002; Papoušek & Papoušek, 1990).

      Stranger Wariness

      Many infants around the world display stranger wariness (also known as stranger anxiety), a fear of unfamiliar people. Whether infants show stranger wariness depends on the infants’ overall temperament, their past experience, and the situation in which they meet a stranger ( Goodvin, Thompson, & Winer, 2015). In many, but not all, cultures, stranger wariness emerges at about 6 months and increases throughout the first year of life, beginning to decrease after about 15 months of age (Bornstein et al., 2013; Sroufe, 1977).

      Recent research has suggested that the pattern of stranger wariness varies among infants. Some show rapid increases and others show slow increases in stranger wariness; once wariness has been established, some infants show steady decline and others show more rapid changes. Twin studies suggest that these patterns are influenced by genetics, because the patterns of change are more similar among monozygotic twins (identical twins who share 100% of their genes) than dizygotic twins (fraternal twins who share 50% of their genes) twins (Brooker et al., 2013).

      As attachments form, infants become more wary and display “stranger anxiety” when in the presence of unfamilar people. In many, but not all cultures, stranger wariness emerges at about 6 months and increases throughout the first year of life.

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      Among North American infants, stranger wariness is so common that parents and caregivers generally expect it. However, infants of the Efe people of Zaire, Africa, show little stranger wariness. This is likely related to the Efe collective caregiving system, in which Efe babies are passed from one adult to another, relatives and nonrelatives alike (Tronick, Morelli, & Ivey, 1992), and the infants form relationships with the many people who care for them (Meehan & Hawks, 2013). In contrast, babies reared in Israeli kibbutzim (cooperative agricultural settlements that tend to be isolated and subjected to terrorist attacks) tend to demonstrate widespread wariness of strangers. By the end of the first year, when infants look to others for cues about how to respond emotionally, kibbutz babies display far greater anxiety than babies reared in Israeli cities (Saarni, Mumme, & Campos, 1998). In this way, stranger wariness may be adaptive, modifying infants’ drive to explore in light of contextual circumstances (Easterbrooks, Bartlett, Beeghly, & Thompson, 2012).

      Stranger wariness illustrates the dynamic interactions among the individual and context. The infant’s tendencies toward social interaction and past experience with strangers are important, of course, but so is the mother’s anxiety. Infants whose mothers report greater stress reactivity, who experience more anxiety and negative affect in response to stress, show higher rates of stranger wariness (Brooker et al., 2013; Waters et al., 2014). Characteristics of the stranger (e.g., his or her height), the familiarity of the setting, and how quickly the stranger approaches influence how the infant appraises the situation. Infants are more open when the stranger is sensitive to the infant’s signals and approaches at the infant’s pace (Mangelsdorf, 1992).

      Lives in Context

      Maternal Depression and Emotional Development

      Depression is characterized by a lack of emotion and a preoccupation with the self that makes it challenging for depressed mothers to care for their infants and recognize their infants’ needs.

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      Challenging home contexts pose risks to infants’ emotional development. One such challenge may come from maternal depression. Depression is not simply sadness; rather, it is characterized by a lack of emotion and a preoccupation with the self that makes it challenging for depressed mothers to care for their infants and recognize their infants’ needs. Although both mothers and fathers can become depressed, with negative implications for their children, most of the research on parental depression examines mothers. Mothers who are depressed tend to view their infants differently than nondepressed mothers and independent observers (Newland, Parade, Dickstein, & Seifer, 2016). Mothers who are diagnosed with depression are more likely to identify negative emotions (i.e., sadness) than positive emotions (i.e., happiness) in infant faces (Webb & Ayers, 2015). When depressed and nondepressed mothers were shown images of their own and unfamiliar infants’ joy and distress faces, mothers with depression showed blunted brain activity in response to their own infants’ joy and distress faces, suggesting muted responses to infants’ emotional cues (Laurent & Ablow, 2013). Depressed women tend to disengage faster from positive and negative infant emotional expressions (Webb & Ayers, 2015). Therefore, challenging behaviors, such as fussiness and crying, and difficult temperaments tend to elicit more negative responses from depressed mothers (Newland et al., 2016).

      In practice, mothers who are depressed tend to be less responsive to their babies, show less affection, use more negative forms of touch, and show more negative emotions and behaviors such as withdrawal, intrusiveness, hostility, coerciveness, and insensitivity (Jennings et al., 2008). Given the poor parent–child interaction styles that accompany maternal depression, it may not be surprising that infants of depressed mothers show a variety of negative outcomes, including overall distress, withdrawn behavior, poor social engagement, and difficulty regulating emotions (Granat, Gadassi, Gilboa-Schechtman, & Feldman, 2017; Leventon & Bauer, 2013). They tend to show greater physiological arousal in response to stressors and are more likely to show a stress response when faced with socioemotional challenges. These infants have difficulty regulating emotion and are at risk for later problems (Suurland et al., 2017). They often show poor attentiveness, limited capacity to interact with objects and people, and difficulty reading and understanding others’ emotions (Lyubchik & Schlosser, 2010). In addition, they are more likely to show deficits in cognitive development, language development, and insecure attachment in infancy and childhood (Liu et al., 2017; Prenoveau et al., 2017).

      The ongoing reciprocal interactions between mothers and infants account for the long-term negative effects of maternal depression (Granat et al., 2017). In one study, maternal depressive symptoms 9 months after giving birth predicted infants’ negative reactions to maternal behavior at 18 months of age and, in turn, higher levels of depressive symptoms on the part of mothers when the children reached 27 months of age (Roben et al., 2015). Similarly, in a sample of infants studied from 4 to 18 months of age, family factors such as maternal depression and the mother’s experience of relationship stress were associated with the infants’ developing strong negative emotions early in infancy, which compromised their emotion regulation capacities (Bridgett et al., 2009). Declines in infants’ regulatory control were in turn associated with negative parenting in toddlerhood, because parents and children interact and influence each other reciprocally.

      Depression can be treated with therapy with or without the accompaniment of antidepressant medication (Hollon et al., 2016). For example, cognitive behavior therapy is particularly successful at treating depression as it teaches depressed individuals to recognize the connections among situations, thoughts, feelings, and behaviors; to examine the accuracy of their beliefs; and to consider alternative explanations (Sockol, 2015). Brief psychotherapy has been shown to be successful in improving maternal depressive symptoms and function (Swartz et al., 2016). Experts argue that in addition to treating maternal depression, parenting interventions are particularly important in helping children of depressed mothers (Goodman & Garber, 2017). Interventions that teach parents how to interact with their children will foster the parent–child relationships that