Laboratory and psychometric measurements of impulsivity among violent and nonviolent female parolees

Background: Female parolees participated in a study to determine the relationship between behavioral and psychometric measures of impulsivity and their previous criminal history. Methods: Subjects were assigned to a violent (n = 10) or nonviolent group (n = 20) based upon their criminal history. Subjects were given two response options defined as: 1) an impulsive choice-small monetary reward (5 cents) after a short fixed delay of 5 sec, and 2) a self-control choice-a lar-ger monetary reward (15 cents) after a variable longer delay initially set at 15 sec. The measure of impulsivity in this behavioral choice procedure was the number of trials on which the subject selected the impulsive option. This definition of impulsivity is based upon an extensive experimental literature in nonhumans and humans related to delay of gratification, that is, the ability to tolerate long delays imposed between the initiation of behavior and the presentation of a reinforcer, Results: Our results indicated that the violent female subjects selected the impulsive option significantly more often than the nonviolent female parolees. Conclusions: The correlation between impulsive and aggressive responses among the female parolees was nonsignificant and negative, in contrast to a significant positive correlation previously reported among male parolees. (C) 1999 Society of Biological Psychiatry.