Shyness trajectories in slow-to-warm-up infants: Relations with child sex and maternal parenting

a r t i c l e i n f o Keywords: Slow-to-warm-up temperament Shyness Maternal parenting Inhibition Infancy Little is known about slow-to-warm-up temperament in infancy. This study examined the trajectory of shyness in children who were slow-to-warm-up in infancy in comparison to children with other temperament profiles in infancy. Participants were 996 mothers and children in the NICHD SECC studied from 6 months to first grade. Latent growth curve modeling showed that children who were slow-to-warm-up in infancy tended to be shy in early childhood, but with increasing age these children became indistinguishable from children who were easy or intermediate. In comparison, children who were difficult in infancy remained more shy than children with other temperament profiles. Maternal sensitive and stimulating/supportive par-enting was associated with less shyness in early childhood for boys who were slow-to-warm-up in infancy. Findings support the distinctiveness of the slow-to-warm-up temperament in comparison to other temperament profiles as well as its potential usefulness for predicting later child outcomes. From birth, infants demonstrate an inherited, consistent behavioral style, or temperament, in their responses to their environment. This characteristic behavioral style is believed to influence parent–child relationships and the child's social development. Much of what we know about the social and behavioral correlates of infant temperament stems from the early research of Thomas and Chess and their colleagues outlined nine dimensions that describe infant temperament: activity level, approach/withdrawal, adaptability, mood, threshold of responsiveness, intensity, distractibility, rhythmici-ty, and attention span/persistence. They then defined three broad profiles of infant temperament: easy, difficult, and slow-to-warm-up (Chess & Thomas, 1999; Thomas et al., 1970). Each profile is defined by a specific constellation of dimensions. The difficult infant (about 10% of Thomas et al.'s sample) is low in rhythmicity, approach, and adaptability, high in intensity, and negative in mood. The easy infant (about 40% of Thomas et al.'s sample) is high in rhythmicity, approach, and adaptability, mild in intensity, and positive in mood. The slow-to-warm-up infant (about 15% of Thomas et al.'s sample) is low in adaptability and approach, low to moderate in activity, mild in intensity, variable in rhythmicity and distractibility, and slightly negative in mood. The remainder of Thomas et al.'s sample (35%) did not fit into one of the three profiles and was labeled intermediate. Subsequent temperament theoretical work has expanded upon the Thomas and Chess (e.g., Chess & Thomas, 1999) conceptualization of temperament, but research has typically …