Aberrant neural processing of moral violations in criminal psychopaths

Abstract

A defining characteristic of psychopathy is the willingness to intentionally commit moral transgressions against others without guilt or remorse. Despite this "moral insensitivity," the behavioral and neural correlates of moral decision-making in psychopathy have not been well studied. To address this issue, the authors used functional magnetic resonance imaging (fMRI) to record hemodynamic activity in 72 incarcerated male adults, stratified into psychopathic (n = 16) and nonpsychopathic (n = 16) groups based on scores from the Hare Psychopathy Checklist-Revised (R. D. Hare, 2003), while they made decisions regarding the severity of moral violations of pictures that did or did not depict moral situations. Consistent with hypotheses, an analysis of brain activity during the evaluation of pictures depicting moral violations in psychopaths versus nonpsychopaths showed atypical activity in several regions involved in moral decision-making. This included reduced moral/nonmoral picture distinctions in the ventromedial prefrontal cortex and anterior temporal cortex in psychopaths relative to nonpsychopaths. In a separate analysis, the association between severity of moral violation ratings and brain activity across participants was compared in psychopaths versus nonpsychopaths. Results revealed a positive association between amygdala activity and severity ratings that was greater in nonpsychopaths than psychopaths, and a negative association between posterior temporal activity and severity ratings that was greater in psychopaths than nonpsychopaths. These results reveal potential neural underpinnings of moral insensitivity in psychopathy and are discussed with reference to neurobiological models of morality and psychopathy.

Figure 1

Severity of moral violation ratings by condition in psychopaths and nonpsychopaths. Bars = standard error.

Figure 2

Interaction in A) anterior temporal cortex (BA 21; x = 57, y = −9, z = −18, F = 17.16, p = .000082 FWE corrected) and B) ventromedial prefrontal cortex (BA 10; x = 12, y = 39, z = −9, F = 6.54, p = .066 FDR corrected) revealing increased activity during moral vs. non-moral and neutral picture viewing in nonpsychopaths but not psychopaths. Bars = standard error.

Figure 3

A) Positive association between right amygdala activity and violation severity ratings present in nonsychopaths (N = 16; x = 33, y = 0, z = −21, t = 4.31, p = .014 FWE corrected), absent in psychopaths (N = 16), and greater in nonpsychopaths than psychopaths (x = 33, y = 0, z = −21; F = 9.43, p = .099 FWE corrected). B) Negative association between right posterior temporal activity (BA 39) and violation severity ratings absent in nonpsychopaths (N = 16), present in psychopaths (N = 16, x = 51, y = −60, z = 27, t = 3.77, p = .035 FWE corrected), and greater in nonpsychopaths than psychopaths (x = 57, y = −51, z = 27; F = 9.83, p < .001, uncorrected). Although both the amygdala and posterior temporal activity – severity rating associations are greater in nonpsychopaths vs. psychopaths, the individual group results illustrate that the latter is due to the negative association in psychopaths (rather than a positive association in nonpsychopaths, as is the case with the amygdala).