Infant Temperament: Stability by Age, Gender, Birth Order, Term Status, and Socioeconomic Status

Abstract

Two complementary studies focused on stability of infant temperament across the first year and considered infant age, gender, birth order, term status, and socioeconomic status (SES) as moderators. Study 1 consisted of 73 mothers of firstborn term girls and boys queried at 2, 5, and 13 months of age. Study 2 consisted of 335 mothers of infants of different gender, birth order, term status, and SES queried at 6 and 12 months. Consistent positive and negative affectivity factors emerged at all time-points across both studies. Infant temperament proved stable and robust across gender, birth order, term status, and SES. Stability coefficients for temperament factors and scales were medium to large for shorter (<9 months) inter-assessment intervals and small to medium for longer (>10 months) intervals.

Stability of temperament in South Korean infants from 6 to 12 to 18 months: Moderation by age, gender, and birth order

“…These results are consistent with the generally similar stability of temperament in girls and boys (with some exceptions: Bornstein et al, 2015; Garcia Coll et al, 1992), in the only studies (to our knowledge), examining child sex as a moderator. However, any discrepancy, or instance of disagreement with respect to differences between girls’ and boys’ temperament stability, could represent a cultural difference, wherein South Korean female and male infants demonstrate stability across different attributes than their U.S. counterparts.…”

“…Parental treatment of first- and laterborns is often not consistent, and siblings’ different experiences (their nonshared environments) in growing-up contribute to making them distinctive individuals (Plomin & Daniels, 1987; Stoolmiller, 1999; Turkheimer & Waldron, 2000). Nonetheless, Bornstein et al (2015) reported no differences in stability of temperament in first- vs. secondborns over the first year of life.…”

“…Studies of infant temperament that considered child sex as a moderator suggest generally similar stability in girls and boys (with some differentiation by dimension; Bornstein et al, 2015; Garcia Coll et al, 1992). At the same time, biological differences between infant girls and boys are compounded by differential treatment they receive from caregivers (Bornstein, 2013).…”

“…Despite infants’ rapid overall development in the first years of life (Bornstein, Arterberry, & Lamb, 2014), relative stability of infant temperament has been consistently reported (e.g., Bornstein et al, 2015; Rothbart, 1986). However, current theory suggests that systems that control/inhibit temperament emerge later in infancy, changing the expression and stability of temperament (Shiner et al, 2012).…”

“…Thus, moderation of temperament stability by child sex may not be consistent, but rather context dependent, and this possibility should be considered further in future research. That said, methodological differences (i.e., different assessment timing and measurement approaches) with Garcia Coll et al (1992) and Bornstein et al, (2015) make alternative explanations plausible.…”