biological rhythms. They are slow to adapt to changes in routine or new situations, react vigorously to change, and have trouble adjusting to new routines.
Slow-to-warm-up temperament: Just as it sounds, slow-to-warm-up babies tend to be inactive, moody, and slow to adapt to new situations and people. They react to new situations with mild irritability but adjust more quickly than do infants with difficult temperaments.
Although it may seem as if all babies could be easily classified, about one third of the infants in the New York Longitudinal Study did not fit squarely into any of the three categories but displayed a mix of characteristics, such as eating and sleeping regularly but being slow to warm up to new situations (Thomas & Chess, 1977; Thomas et al., 1970).
Another influential model of temperament, by Mary Rothbart, includes three dimensions (Rothbart, 2011; Rothbart & Bates, 2007):
Extraversion/surgency: the tendency toward positive emotions. Infants who are high in extraversion/surgency approach experiences with confidence, energy, and positivity, as indicated by smiles, laughter, and approach-oriented behaviors.
Negative affectivity: the tendency toward negative emotions, such as sadness, fear, distress, and irritability.
Effortful control: the degree to which one can focus attention, shift attention, and inhibit responses in order to manage arousal. Infants who are high in effortful control are able to regulate their arousal and soothe themselves.
From this perspective, temperament reflects how easily we become emotionally aroused or our reactivity to stimuli, as well as how well we are able to control our emotional arousal (Rothbart, 2011). Some infants and children are better able to distract themselves, focus their attention, and inhibit impulses than others. The ability to self-regulate and manage emotions and impulses is associated with positive long-term adjustment, including academic achievement, social competence, and resistance to stress, in both Chinese and North American samples (Chen & Schmidt, 2015).
Infant temperament tends to be stable over the first year of life but less so than childhood temperament, which can show stability over years, even into adulthood (Bornstein et al., 2015). In infancy, temperament is especially open to environmental influences, such as interactions with others (Gartstein, Putnam, Aron, & Rothbart, 2016). Young infants’ temperament can change with experience, neural development, and sensitive caregiving (e.g., helping babies regulate their negative emotions) (Jonas et al., 2015; Thompson et al., 2013). As infants gain experience and learn how to regulate their states and emotions, those who are cranky and difficult may become less so. By the second year of life, styles of responding to situations and people are better established, and temperament becomes more stable. Temperament at age 3 remains stable, predicting temperament at age 6 and personality traits at age 26 (Dyson et al., 2015).
Context and Goodness of Fit
Like all aspects of development, temperament is influenced by reciprocal reactions among individuals and their contexts. An important influence on socioemotional development is the goodness of fit between the child’s temperament and the environment around him or her, especially the parents’ temperaments and childrearing methods (Chess & Thomas, 1991). Infants are at particular risk for poor outcomes when their temperaments show poor goodness of fit to the settings in which they live (Rothbart & Bates, 1998). For example, if an infant who is fussy, difficult, and slow to adapt to new situations is raised by a patient and sensitive caregiver who provides time for him or her to adapt to new routines, the infant may become less cranky and more flexible over time. The infant may adapt her temperament style to match her context so that later in childhood, she may no longer be classified as difficult and no longer display behavioral problems (J. Bates, Pettit, Dodge, & Ridge, 1998). If, on the other hand, a child with a difficult temperament is reared by a parent who is insensitive, coercive, and difficult in temperament, the child may not learn how to regulate her emotions and may have behavioral problems and adjustment difficulties that worsen with age, even into early adolescence and beyond (Pluess, Birkbeck, & Belsky, 2010). Accordingly, when children are placed in low-quality caregiving environments, those with difficult temperaments respond more negatively and show more behavior problems than do those with easy temperaments (Poehlmann et al., 2011).
An infant’s temperament may be stable over time because certain temperamental qualities evoke certain reactions from others, promoting goodness of fit. Easy babies usually get the most positive reactions from others, whereas babies with a difficult temperament receive mixed reactions (Chess & Thomas, 1991). For example, an “easy” baby tends to smile often, eliciting smiles and positive interactions from others, which in turn reinforce the baby’s “easy” temperamental qualities (Planalp, Van Hulle, Lemery-Chalfant, & Goldsmith, 2017). Conversely, a “difficult” baby may evoke more frustration and negativity from caregivers as they try unsuccessfully to soothe the baby’s fussing. Researchers found that mothers who view their 6-month-old infants as difficult may be less emotionally available to them (Kim & Teti, 2014). Babies’ emotionality and negative emotions predict maternal perceptions of parenting stress and poor parenting (Oddi, Murdock, Vadnais, Bridgett, & Gartstein, 2013; Paulussen-Hoogeboom, Stams, Hermanns, & Peetsma, 2007). Goodness of fit at 4 and 8 months of age predicts a close bond with caregivers at 15 months (Seifer et al., 2014).
Temperament can also be related to mothers’ own temperament, as well as their expectations about their infants and their ability to parent (Grady & Karraker, 2017). In one study, mothers who, prior to giving birth, considered themselves less well equipped to care for their infants were found to be more likely to have infants who showed negative aspects of temperament, such as fussiness, irritability, and difficulty being soothed (Verhage, Oosterman, & Schuengel, 2013). This suggests that perceptions of parenting may shape views of infant temperament—and thereby shape temperament itself. In other research, 3 months after giving birth, new mothers’ feelings of competence were positively associated with infant temperament. Mothers’ beliefs about their ability to nurture are shaped by the interaction between their infants’ traits and their own parenting self-efficacy, as well as their opportunities for developing successful caregiving routines (Verhage et al., 2013). This contextual dynamic has been found to hold true across cultures. Both British and Pakistani mothers in the United Kingdom reported fewer problems with their infants’ temperaments at 6 months of age when the mothers had a greater sense of parenting efficacy and displayed more warm and less hostile parenting styles (Prady, Kiernan, Fairley, Wilson, & Wright, 2014).
As mentioned earlier, socioemotional development is a dynamic process in which infants’ behavior and temperament styles influence the family processes that shape their development. Sensitive and patient caregiving is not always easy with a challenging child, and adults’ own temperamental styles influence their caregiving. A poor fit between the caregiver’s and infant’s temperament can make an infant more fussy and cranky. When a difficult infant is paired with a parent with a similar temperament—one who is impatient, irritable, and forceful—behavioral problems in childhood and adolescence are likely (Chess & Thomas, 1984; Rubin, Hastings, Chen, Stewart, & McNichol, 1998).
The most adaptive matches between infant temperament and context can sometimes be surprising. Consider the Maasai, an African semi-nomadic ethnic group. In times of drought, when the environment becomes extremely hostile, herds of cattle and goats die, and infant mortality rises substantially. Under these challenging conditions, infants with difficult temperaments tend to survive at higher rates than do those with easy temperaments. Infants who cry and are demanding are attended to, are fed more, and are in better physical condition than easy babies, who tend to cry less and therefore are assumed to be content (Gardiner & Kosmitzki, 2018). Thus, the Maasai infants with difficult temperaments demonstrate higher rates of survival because their temperaments better fit the demands of the hostile context in which they are raised. Early experience can influence emotional
