Decade of Behavior Distinguished Lecture: Development of physical aggression during infancy

Violence is a major public concern in our modern societies. To prevent this violence we need to understand how innocent children grow into violent adolescents and adults. It is generally believed that humans are most frequently physically aggressive during adolescence and early adulthood. With longitudinal studies of large samples of children from different countries that followed them from infancy to adulthood, scientists tried to discover at what age individuals learn how to physically aggress. These studies indicated that the peak age for physical aggression was not during early adulthood, adolescence, or even kindergarten, but rather between 24 and 42 months after birth. Although there are important individual differences in children's use of physical aggression, most of them will learn to use socially acceptable alternatives when angry or frustrated before they enter school. To prevent chronic physical aggression and its terrible consequences over the whole life course, modern societies should provide children with the optimal prenatal and postnatal environments.