Psychopathy and Event-Related Brain Potentials (ERPs) associated with attention to speech stimuli

Event-related brain potentials (ERPs) were used to determine whether low left-hemisphere arousal or unusual cortical responses to speech stimuli might be associated with anomalies in language function that reportedly occur when psychopaths perform lateralized information-processing tasks. ERPs to phonemic stimuli were recorded while 11 psychopathic (P) and 13 nonpsychopathic (NP) male prison inmates performed a Single-Task and a Dual-Task. In the Single-Task, a speech discrimination ‘oddball’ paradigm, the subject was required to respond whenever a target stimulus (the less frequent of two phonemes) occured. In the Dual-Task, he had to respond to target stimuli while simultaneously performing a perceptual-motor (distractor) task. There were no group differences in ERP measures of central arousal (N100) during performance of the Single- and Dual-Tasks. For both groups, the P300 component of the ERP to the target stimulus was smaller and had longer latency during the Dual-Task than during the Single-Task, indicating that in the Dual-Task phonemic discrimination and the perceptual-motor task completed for similar perceptual resources. Overlapping Group P's P300 responses to the target stimulus during the Dual-Task was a vertex and asymmetric (left-hemisphere) positive slow wave (SW), suggesting unusual speech processing in psychopaths under conditions of distraction, perhaps related to reduced sensitivity to the sequential probabilities associated with events presented in an auditory channel. The results were consistent with the hypothesis that psychopaths have limited left-hemisphere resources for processing linguistic stimuli.