Characterizing aggressive behavior in a forensic population.

The concept of a dichotomous versus a continuous aggression model continues to be debated within the research literature. The Impulsive/Premeditated Aggression Scale (IPAS; M. S. Stanford, R. J. Houston, C. W. Mathias, et al., 2003) is a newly developed self-report instrument designed to classify an individual's aggressive behavior as predominantly premeditated or predominantly impulsive. The IPAS consists of 30-items that are scored on a 5-point Likert scale. This study used a nonrandom sample of convenience (N = 85) from a forensic state hospital. Principal-components analysis of the 30 items revealed 2 distinct factors (Impulsive and Premeditated Aggression), which accounted for 33% of the variance. The results of this study further validate the bimodal classification of aggression through its application to a forensic sample. The implications for general assessment, diagnosis, and treatment are discussed.