In this study, we attempted to develop the Functional Aggression Scale (FAS) based on a two-process model of aggressive motivation (Ohbuchi, 1993), which postulated that people share social knowledge of four different functions of aggression, that is, avoidance/defense, influence/coercion, punishment/retaliation, and identity. Assuming that those who are easily activated of the concepts or concerns in social conflicts which are connected to these aggressive functions are likely to choose aggression as a response to such situations, we construed items to measure these aggressive functions, focusing on 14 related-personality traits involving high accessibility to these concepts or concerns. In the scale analysis (alpha coefficients and principal components) based on the FAS responses of male 79 adult prison inmates and 137 boys in a juvenile classification center, internal consistency was high in the avoidance/defense and identity scales, but several inappropriate items were found in other two scales. We divided the prison inmates into violent and non-violent groups based on their self-report of violence and found that the violent group showed significantly higher scores on 3 scales of FAS than the non-violent group. A comparison of violent and non-violent groups among the juvenile boys based on their official records of criminal violence did not produce differences on any FAS scale. In psychologists' ratings of FAS for the boys, however, the two FAS scales significantly discriminated the two groups. As a result, the present study demonstrated a certain level of validity of FAS, but the items must be reconsidered to improve reliability of the influence/coercion and punishment/retaliation scales.
