Thesis (Ph.D.)--University of Delaware, 2009. / Principal faculty advisor: James E. Hoffman, Dept. of Psychology. Includes bibliographical references.

Thesis (M.Sc.) - Swinburne University of Technology, Brain Sciences Institute, 2008. / A thesis submitted for M.Sc by Research, Brain Sciences Institute, Swinburne University of Technology - 2008. Typescript. Includes bibliographical references (p. 117-153)

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Research on the Auditory Brainstem Response (ABR) has been dominated by attempts to develop techniques to enhance the clarity of the ABR waveform and to define the parameters that separate normal from abnormal responses. While the effects of stimulus rate are clearly documented, the effects of stimulus polarity on the ABR are not. There may be an interaction of polarity and rate which accounts for the inconsistent results reported in the literature. This study examined the effect of stimulus rate and polarity for waves I, III, and V, on the ABR latency, amplitude, and amplitude ratio. Rarefaction and condensation clicks were delivered at rates of 11.l; 21.1, 41.1, and 81.1 clicks per second. Fourteen male subjects were used, each having normal hearing thresholds and normal middle ear function.

This research aimed to explore and contextualise research on the electrophysiological potentials evoked in response to human face recognition within the South African context. Previous research provides evidence that there is a measurable difference in the electrophysiological response to faces of people of other racial groups when compared to the response to one’s own race group. The difference is seen in greater peak amplitudes in response to one’s own-race (indicating greater attention being granted) in comparison to the other-race. This has been labelled the Cross-Race Effect. This research also attempted to expand on previous research in the use of a mixed-race sample and realistic colour images, in contrast to previously used greyscale images. A purposive sample of 40 students at the University of the Witwatersrand was split equally between gender and race (Black and White) with an Indian control group. The electrical potentials elicited by the facial stimuli were extracted from the ongoing electroencephalograms. The results obtained displayed inverse results to those found internationally, with Black participants eliciting no differences between racial groups, and White participants eliciting a greater peak amplitude to Black (other-race) faces. A gender effect was also seen, with White participants eliciting greater peak amplitudes towards female faces, while Black participant again showed no differences between male and female faces. Trends displayed in the results, and the significance thereof, are discussed, and the importance of the effect of society of developmental neurology is highlighted, with the rephrasing of cultural neuroscience to Socio-Cultural Neuroscience. The results ultimately suggest that the internationally seen cross-race effect is absent in a young South African population (with the principle of increased exposure leading to increased attention still in effect), indicating that South Africa is beginning to move away from racial discrimination, and moving towards a future of true integration and equality.

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