[Causal relationship between assertiveness and adjustment in children: A short-term longitudinal study].

This study examined the causal relationships between assertiveness and both internal and external adjustment in children. Elementary school children in grades four through six (N = 284) participated in the study, which used a short-term longitudinal design. The children completed questionnaires twice during a 6-months period. They responded to assertiveness questionnaires that included two components: "self-expression" and "consideration of others". They also completed a self-esteem scale as an index of internal adjustment, and the Class Life Satisfaction scale as an index of external adjustment. There was a positive causative relationship between "self-expression" and internal adjustment and between "consideration for others" and external adjustment. In addition, the effects on adjustment varied according to the type of assertiveness. Cluster analysis and MANOVA indicated that the group with high "self-expression" and "consideration for others" had high internal and external adjustment, while the children with poor assertiveness showed the lowest degree of adaptivity.