This study tested the hypothesis that low electrodermal activity (EDA) & fast habituation reflect impulsivity & violence as a biological part of suicidal behavior. EDA values were measured in 11 female patients with personality disorders (PA) & histories of suicide attempts. Their EDA values were compared to nonsuicidal/suicidal depressed or schizophrenic patients. Significant differences were found between the PA group & nonsuicidal depressives, but no other group. (31 refs.)