Phonological processing in psychopathic offenders

Abstract

Recent research has demonstrated that psychopathic offenders exhibit dynamic cognitive and behavioral deficits on a variety of lab tasks that differentially activate left hemisphere resources. The Left Hemisphere Activation (LHA) hypothesis is a cognitive perspective that aims to address these deficits by conceptualizing psychopathy as a disorder in which behavior and cognitive processing change dynamically as a function of the differential taxation of left hemisphere resources. This study aimed to investigate whether psychopathic traits are associated with electrophysiological anomalies under conditions that place differential demands on left hemisphere language processing systems. We examined in a sample of 43 incarcerated indivdiuals the evocation of the N320, an event-related potential (ERP) elicited by nontarget stimuli during a phonological/phonetic decision task that has been shown to elicit greater activation and cognitive processing within the left hemisphere than the right hemisphere. Findings for a subsample of 18 offenders low in psychopathic traits were generally consistent with previous findings in healthy individuals, suggesting similar electrophysiological activity during phonological processing. However, psychopathic traits impacted the amplitude of the N320. Higher levels of psychopathic traits were associated with reduced left-lateralization in phonological processing as well as enhanced ERP differentiation between pronounceable and nonpronounceable stimuli. These findings provide physiological evidence of a relationship between psychopathic traits and anomalous language processing at the phonological level of word processing.

Keywords: Antisocial personality disorder; Electroencephalography (EEG); Event-related potential (ERP); Language; Left Hemisphere Activation (LHA) hypothesis; N320; Psychopathy.

Figure 1.

Averaged ERPs elicited by pronounceable nontarget stimuli and nonpronounceable stimuli across all participants during a rhyming task at T3, T4, T5, and T6.

Figure 2.

Scatterplot illustrating the significant positive correlation (r = .31, p = .04) between the mean difference in N320 amplitude between stimulus types (i.e., nonpronounceable vs. pronounceable) across all electrodes and total PCL-R score. As PCL-R total scores increase, the difference in N320 amplitude between nonpronounceable and pronounceable stimuli increases.

Figure 3.

Scatterplot illustrating the negative correlation (r = −.31, p = .05) between the mean difference in N320 amplitude between hemispheres (i.e., right and left) across all electrodes and total PCL-R score. As PCL-R total scores increase, the difference in N320 amplitude between left and right hemispheres decreases.