Studies of violent and nonviolent male parolees: I. Laboratory and psychometric measurements of aggression.

Male parolees were recruited into a laboratory study to determine the relationship between their previous aggression history, psychometric measures of aggression, and behavioral measures of aggressive responding using a laboratory methodology: the Point Subtraction Aggression Paradigm. Subjects were assigned to a violent or nonviolent group based upon their criminal history. Subjects participated in sessions in which they were given three response options defined as: (1) nonaggressive responding which earned money, (2) aggressive responding which ostensibly subtracted money from another fictitious person, (This responding was defined as aggressive since it resulted in the ostensible delivery of an aversive stimulus (subtraction of money) to another person), and (3) escape which protected the subject's earnings from subtractions initiated by the other person. Results indicated that the violent subjects emitted significantly more aggressive responses than subjects in the nonviolent group. The number of aggressive responses parolees emitted was significantly correlated with most psychometric measures of aggression. This study provides external validity for our laboratory measurement of human aggressive responding, since aggressive responding was directly related to violent criminal histories.