Aggressive behaviors in children and adolescents have undergone important conceptual and definitional modifications in the past two decades. In particular, subtypes of aggression have been proposed that separate the form and the function of the aggressive behaviors (i.e., social vs. physical aggression; reactive vs. proactive aggression).…

Cognitive activity of children from 1.5 to 5 years of age participating in problem solving and in spontaneous play was analyzed in terms of the successive coordination of existing patterns and the incorporation of new mental components. Analysis identified a series of developmental levels. (Author/RH)