Normative Trends in Physically Aggressive Behavior: Age-Aggression Curves from 6 to 24 Months

Abstract

Objective To investigate age-related trends in physically aggressive behaviors in children before age 2 years. Study design A normative US sample of 477 mothers of 6-to 24-month-old children reported on the frequency of 9 interpersonally directed aggressive child behaviors, and hurting animals, in the past month. Results Almost all (94%) of the children were reported to have engaged in physically aggressive behavior in the past month. Based on 2-part regression models, the prevalences of kicking (OR, 1.70; P = .023), pushing (OR, 3.22; P < .001), and swiping (OR, 1.78; P = .018) increased with years of age, but the prevalence of hair pulling decreased with age (OR, 0.55; P = .020). The prevalences of hitting and throwing increased initially, then plateaued at age 18-20 months, and then decreased (quadratic aOR, 0.13 and 0.16; P < .001 and .010, respectively). The frequencies of hitting (R 2 = .05; P < .001) and throwing (R 2 = .03; P = .030) increased, and the frequencies of hair pulling (R 2 = .07; P < .001) and scratching (R 2 = .02; P = .042) decreased with age (P values adjusted for false discovery rate). Conclusions Physically aggressive behavior in the 6-to 24-month age range appears to be nearly ubiquitous. Most, but not all, forms of physical aggression increase with age. These results can guide pediatricians as they educate and counsel parents about their child's behavior in the first 2 years of life.

The distinction between provoked and unprovoked aggression in toddlerhood, and associations with empathy‐related processes

“…Although there is some research on angry aggressiveness (Hay et al., 2010; Perra et al., 2021), information about when aggression is enacted or what precedes or accompanies an aggressive act is often missing in the research on early aggression. For instance, when relying on parental reports, items usually just tap the prevalence or frequency of behaviors such as hitting, kicking, or biting (Alink et al., 2006; Côté et al., 2006; Lorber et al., 2019; Nagin & Tremblay, 1999; Nærde et al., 2014; Tremblay et al., 2004). Yet, without knowing where and when such aggressive acts occur, it would be premature to conclude that frustration is a single or primary underlying cause of aggression (Dahl, 2016).…”

Aggression in toddlers: Associations with temper loss and parent‐child conflict

“…Lorber et al. (2019) extended these findings: although kicking, pushing, and throwing objects and swiping at people became more common between 6 and 24 months of age, hair‐pulling and scratching people became less so. Together, these data suggest that distinct aggressive behaviors may develop differently in the first few years of childhood, with pushing, hitting, and kicking becoming more established as biting and hair‐pulling fade.…”

“…Some definitions require an intent to harm or a means‐end calculation about the impact or instrumental value of the act (e.g., Dodge et al., 2006; Maccoby, 1980). However, a cognition‐based definition of infant PA relies on capacities that appear in the toddlerhood and preschool years (Tomasello et al., 2005), which is later than the onset of kicking, pushing, hitting, biting, pinching, scratching, and hair‐pulling (Lorber et al., 2019). Thus, to capture the development of PA from its earliest instances, we define interpersonal PA topographically as an act of physical force toward another person, in line with Tremblay (2000).…”

“…PA undergoes considerable change in the first 2 years of childhood. Findings by three separate research groups (Hay et al, 2010;Lorber et al, 2018Lorber et al, , 2019Naerde et al, 2014;Perra et al, 2021) suggest that PA is displayed by children as young as 6 and 8 months old and increases in the first and second years of life, peaking at a prevalence of 74%. Evidence also suggests that not all physically aggressive behaviors increase over this period.…”

The Child-to-Parent Violence Functions Scale (CPV-F): Development and Validation

“…Participants were excluded if they were not over the age of 18; if they were not an Australian resident; or if their young person was not aged between 5 and 24 years. The minimum age of five years was selected to exclude any developmentally normal aggression (Lorber et al, 2019), which is primarily due to a lack of language development, before this age. The maximum age of 24 was selected because many young people in Australia continue to live at home after turning 18 (Australian Institute of Family Studies, 2022) and are still considered 'youth' until turning 25.…”