Infant externalizing behavior as a self-organizing construct.

Abstract

We evaluated the extent to which the externalizing behavior construct is self-organizing in the first 2 years of life. Based on dynamic systems theory, we hypothesized that changes in physical aggression, defiance, activity level, and distress to limitations would each be predicted by earlier manifestations of one another. These hypotheses were evaluated via mothers' and fathers' reports of 274 infants' externalizing behaviors at 8, 15, and 24 months of child age. Eight-month measures of physical aggression, activity level, and/or distress to limitations explained increases in physical aggression, defiance, activity level, and distress to limitations from 8 to 15 months. Increases in defiance and activity level from 15 to 24 months were predicted by 15-month physical aggression and/or distress to limitations. These findings suggest that the externalizing behavior construct is formed by dynamic interplay among its individual elements, particularly between 8 and 15 months.

The Development of Individual Physically Aggressive Behaviors from Infancy to Toddlerhood

“…The intervention is not a focus of the present manuscript and is described in Heyman et al (2017) and Halford, Petch, and Creedy (2010). As reported in Lorber et al (2014, it had no impact on physical aggression or other externalizing behaviors at any age in the present sample.…”

“…For example, Lorber, Del Vecchio, and Slep (2015) reported a .40 stability of physical aggression from 8 to 24 months and Alink et al (2006) reported a .49 stability of physical aggression from 12 to 24 months. Further, in Lorber et al (2014) and Van Zeijl et al (2006), physical aggression in the 8-to 15-month age range was associated with parent report measures of difficult temperament, distress to limitations, activity level, and nonverbal defiance, as well as with observational measures of physical struggle and distress vocalizations. Moreover, a composite of physical aggression and anger at 6 months of age was associated with observed peer-directed physical force at one year of age (Hay et al, 2010) and parent-reported aggression at age three (Hay et al, 2014).…”

“…As pointed out by several writers (Hay, 2016;Lorber, Del Vecchio, & Slep, 2014;Tremblay, 2000), there is disagreement about whether it is appropriate to refer any behavior as "aggressive" when performed by infants. Some theorists prefer a definition of aggression that requires intent to harm and/or a kind of means-end calculation about what the impact or instrumental value of the act is (e.g., Dodge, Coie, & Lynam, 2006;Maccoby, 1980).…”

“…The findings of at least three studies of physical aggression covering the 8-to 24-month age range suggest that individual physically aggressive behaviors reflect a single underlying factor Lorber, Del Vecchio, & Slep, 2014;Naerde et al, 2014). …”

“…We know that some aggressive behaviors become less prevalent with age, while others become more prevalent with age as the infant becomes a toddler (present article). We know that they cluster together both in person-centered analyses (i.e., latent class analysis; present article) and variable-centered analyses (i.e., factor analysis; Alink et al, 2006;Lorber et al, 2014;Naerde et al, 2014). We know that they have continuity over time and that this continuity is primarily heterotypic (present article).…”