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Psychopathy is a complex personality disorder denned by a constellation of affective and behavioral characteristics. There is accumulating behavioral evidence suggesting that the condition is associated with impairments in affective, cognitive, and language functions. However, relatively little is known regarding the neural systems underlying these abnormalities. The present thesis is comprised of five experiments designed to elucidate and characterize the abnormal functional architecture underlying these abnormalities in psychopathic criminals. In Experiments 1 and 2, functional magnetic resonance imaging (fMRI) was used to elucidate the neural systems underling abnormal semantic and affective processes in these individuals. In Experiments 3, 4 and 5, event-related potentials (ERPs) were used to characterize the temporal features of cognitive and language functions in psychopaths. The results from Experiment 1 revealed that compared to control participants, psychopaths performed more poorly and failed to showed the appropriate neural differentiation between abstract and concrete stimuli during a lexical decision task. These deficits were located in the right anterior superior temporal gyrus. The results from Experiment 2 indicated that psychopaths, relative to control participants, showed less activation for processing affective stimuli than for neutral stimuli in several neural regions, including the right amygdala/hippocampal formation, left parahippocampal gyrus, ventral striatum, and in the anterior and posterior cingulate. Psychopaths did show greater activation for processing affective than for neutral stimuli in regions located outside the limbic system, including bilateral inferior frontal gyrus. These latter data suggesting that psychopaths used different neural systems than did controls for performing the task. The results from Experiments 3 and 4 indicated that psychopathy is associated with abnormalities in the P3 ERP component elicited by target stimuli during visual and auditory oddball tasks. In addition, the psychopaths' ERPs to visual and auditory target stimuli were characterized by large fronto-central negativities in the 350-600 millisecond time window. These fronto-central ERP negativities are similar to those observed for patients with temporal lobe damage. In Experiment 5, using a standard sentence processing paradigm, no group differences were observed between psychopaths and nonpsychopaths in the amplitude of the N400 potential elicited by terminal words of sentences that were either congruent or incongruent with the previous sentence context. These results indicate that the abnormal fronto-central ERP negativities observed in previous studies of language function in psychopaths are not related to processes involved in the generation of the N400. Taken together, these data suggest that one of the cardinal abnormalities in psychopathy is abnormal semantic processing of conceptually abstract information and affective information and that these abnormalities are related to the function of neural circuits in the anterior temporal lobes and lateral frontal cortex.

The experiments in this thesis used behavioural measures and event-related potentials (ERPs) to investigate the influence of race on face processing in the brain. Previous behavioural research has highlighted an own-race effect in face processing, whereby individuals are more accurate at recognizing own-race compared to other-race faces. The current Thesis examined the own-race effect at perceptual and neural levels. Social influences on the own-race effect were also investigated, such as other-race experience, anxiety and implicit social bias, as these may account for differential own- versus other-race face processing. The main aim of the experiments contained in this thesis was to delve deeper into the examination of own and other-race face perception through a series of original experiments. Participants performed a variety of perceptual discrimination and identification tasks, and completed measures of explicit other-race experience and implicit racial bias to record their perceptions of other-race individuals. Chapters 2-4 saw the development of a new paradigm that tested the own-race effect in perception, in contrast to traditional recognition memory investigations. In Chapter 2 the own-race effect was investigated developmentally and found across three age-groups, and was larger in the two older age-groups. Chapters 3 and 4 found that the own-race effect differed across racial groups, and that social variables such as other-race experience influenced the strength of the own-race effect. In the latter experimental chapters, ERPs revealed that the behavioural own-race effect was evident at a neural level. Chapter 7 demonstrated that face-related stages of processing in the brain were sensitive to race of face. In Chapters 8 and 9, the sensitivity of face processing to own and other-race emotional expression processing was also examined. The additional social factor of emotional expression was explored in order to further the investigation of socially relevant information processing from the face. Findings from the last two experimental chapters demonstrated differential emotional face processing for own- versus other-race faces. Confirming the findings of the behavioural experiments, own- versus other-race emotion processing varied across racial groups and was subject to social influences such as other-race experience, intergroup anxiety and implicit racial bias. Overall, behavioural and neural investigations of the own-race effect demonstrated the influence of social variables such as other-race experience, intergroup anxiety and implicit racial bias on the way in which individuals processed own- versus other-race faces in the human brain.

Introduction: Psychophysical and electrophysiological techniques have shown that chromatic contrast sensitivity improves between infancy and adolescence. In adults, electrophysiological and psychophysical methods usually agree. However, in infants electrophysiological techniques may underestimate ability to see chromatic contrast (Suttle et al., 2002). It is not known if the discrepancy between electrophysiological and psychophysical methods continues during childhood nor whether the chromatic VEP can be used as an indicator of colour perception in children. Purpose: To investigate the transient L-M chromatic visual evoked potential and its ability to indicate perception (psychophysical thresholds) of chromatic stimuli in children and adults. In particular, to determine whether a discrepancy between VEP and psychophysical L-M thresholds exists during childhood and if so, to gain some understanding about the nature of the discrepancy. Methods: Transient chromatic VEPs were recorded in children (aged 4.5-13 years) and adults (aged 20-40 years). VEP thresholds were compared with psychophysical thresholds (within-subjects comparison). Because the VEPs of the children were less intra-individually repeatable in morphology than those of the adults, post-hoc objective analysis of the VEPs, linear (Fourier) and nonlinear dynamical (Grassberger and Procaccia's (1983) correlation dimension) analyses, was conducted. Results: VEP and psychophysical estimates of chromatic contrast thresholds agreed using a variety of methods in the adults. In the children, however, the objective methods of assessment (extrapolation from Fourier-derived amplitudes and the correlation dimension) were more accurate than the methods that employed subjective evaluations of VEP morphology. Conclusion: The L-M transient chromatic VEPs of both children (aged 4.5-13 years) and adults appear to contain chromatic information, even in the absence of repeatable VEP morphology and should therefore be able to indicate chromatic perception (psychophysical thresholds). However, the chromatic information may be present as a nonlinear dynamical signal, which may require objective methods (Fourier analysis, the correlation dimension) to reveal the chromatic signal. The greater intra-individual variability of VEP morphology in children compared to adults may reflect poorer precision when switching between cortical states in children's brains. Alternatively, interactions between the immature visual system of the children and their general EEG may occur. Children's VEPs should therefore be interpreted differently to adult VEPs.

Thesis (Ph. D.)--University of California, San Diego and San Diego State University, 2007. / Title from first page of PDF file (viewed January 9, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 258-271).

Thesis (M.S.)--University of Texas at El Paso, 2007. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Thesis (Ph.D.)--Tufts University, 2004. / Adviser: Phillip J. Holcomb. Submitted to the Dept. of Psychology. Includes bibliographical references (leaves 211-216). Access restricted to members of the Tufts University community. Also available via the World Wide Web;

Thesis (M.A.)--University of Nevada, Reno, 2007. / "August, 2007." Includes bibliographical references (leaves 10-11). Online version available on the World Wide Web.

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves [97]-103).

Thesis (Ph. D.)--University of Oregon, 2004. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 432-460). Also available for download via the World Wide Web; free to University of Oregon users.