Understanding and Preventing Violence, Volume 2: Biobehavioral Influences (1994)
Chapter: PSYCHOPHYSIOLOGIC STUDIES RELATED TO VIOLENCE
The studies of Lansdell and a confirmatory finding by Sundet (1986) are summarized in Table 11. One additional study is included in this table although it does not pertain directly to the effects of temporal lobe surgery or epilepsy. Instead, this study by Hampson and Kimura (1988) shows that women exhibit large and significant ''reciprocal performance fluctuations over the menstrual cycle in two types of skills." The possibility exists that these hormonal effects in the female may have some bearing on the apparently greater resilience of the female brain; further, it is conceivable that these sex differences may have some bearing on the greater propensity for male aggressiveness/violence. If it is true that violence is a symptom due to a lesion somewhere in the brain, then the increased prevalence of the symptom in the male may be due to the greater vulnerability of the male brain to injury and/or to the greater apparent plasticity of the female brain. Clearly, much additional research would be needed before the merit of this hypothesis could be evaluated.
PSYCHOPHYSIOLOGIC STUDIES RELATED TO VIOLENCE
There are numerous psychophysiologic techniques that have been employed in the study of disordered populations. However, even a cursory review of these would go beyond the limits of this paper. We will refer here only to some recent studies of Event-Related Brain Potentials (ERPs) in populations relevant to the current discussion: prison inmates rated high on a psychopathy scale, although not necessarily selected for unusual violence or aggressiveness. Other research, however (Hare and McPherson, 1984), has shown that psychopaths are more likely than other criminals to commit violent and aggressive crimes. In this series of studies (Jutai et al., 1987; Hare and Jutai, 1988) summarized in Table 12, the findings suggest that high psychopathy is associated with poor information processing capacities. Specifically, those inmates rated high in psychopathy showed both ERP and neuropsychologic evidence of left hemisphere dysfunction and/or weak or unusual lateralization of language functions. The results are compatible with the view that psychopaths have fewer language processing resources than do normal individuals.
The results of these studies are important for two reasons: (1) they highlight a possible cognitive deficit in persons who may commit violent crimes; and (2) they exemplify a powerful noninvasive technique (ERPs) for studying brain functions and information processing in violence-prone populations. Such research, as Duncan (1990) and colleagues (1985, 1989) have shown, can help illuminate
