In general, boys express more activity and emotional negativity than girls within the first year of life. Although this trend may continue in development, results with regard to anger are few and inconsistent up to 4 or 5 years of age. Based on a few studies, it may be true that boys up to 18 months of age express more anger in facial expressions and physical struggling, whereas girls express more anger in vocalization. If there is a difference between males and females in the threshold that anger must cross to trigger overt aggression, this difference may exist before the age of 4 or 5 years. By this age, girls tend to consciously suppress the expression of anger. After the age of 7 or 8 years, adult patterns emerge and boys express more anger. The situations that are the most frequent causes of anger differ for women and men; these differences are likely to emerge as peer relations and friendships become a more salient influence for girls and boys. There are no studies to indicate when females' tendency to cry in response to anger-provoking situations becomes consistently greater than that of males. A different picture emerges when the focus is on aggression rather than anger. Boys show more physical aggression than girls; this difference appears in children as young as 1 to 2 years of age, contrary to some suggestions . Despite an overall reduction in physical aggression after 2 to 3 years of age , the sex difference remains. Archer  found no change in effect size for this sex difference in observational studies from preschool to school age. Knight et al's  finding that the effect size of sex differences is greatest in children who are younger than 4 years of age and diminishes significantly thereafter may be due to their pooling of different measures of aggression. At this point, our understanding of sex differences in aggression is more advanced than our understanding of differences in anger. Given that anger at 2 years of age predicts subsequent psychopathology , that the persistence of tantrums to age 5 may mark an increased risk of conduct disorder , and that tantrum persistence to age 8 predicts poor life adjustment in boys , it is clear that further analysis should be undertaken. This should include more systematic meta-analysis of effect size organized by anger provocation, type of measurement, and mode of anger expression to make our understanding of anger development comparable to our understanding of aggression development.
|Original language||English (US)|
|Number of pages||16|
|Journal||Child and adolescent psychiatric clinics of North America|
|State||Published - Jul 2004|