Feature extraction is an important step in the classification of high-dimensional data such as face images. Furthermore, linear feature extractors are more prevalent due to computational efficiency and preservation of the Gaussianity. This research proposes a simple and fast linear feature extractor approximating the sufficient statistic for Gaussian distributions. This method preserves the discriminatory information in both first and second moments of the data and yields the linear discriminant analysis as a special case. Additionally, an accurate upper bound on the error probability of a plug-in classifier can be used to approximate the number of features minimizing the error probability. Therefore, tighter error bounds are derived in this work based on the Bayes error or the classification error on the trained distributions. These bounds can also be used for performance guarantee and to determine the required number of training samples to guarantee approaching the Bayes classifier performance.

The literature shows that maxillofacial fractures in children are uncommon. Although the Department of Oral and Maxillofacial Surgery of the Faculty of Dentistry, of the University of the Western Cape, has been providing a service to the Red Cross Children&rsquo / s Hospital (RXH) for the past twenty years, no study had been undertaken to determine the age, gender, number of patients per year, aetiology, patterns, and management of maxillofacial fractures at this institution. A retrospective records based study was undertaken to determine these features. This study accessed the records of patients seen at the trauma unit at RXH, from 1994 to 2003 inclusive, and referred for maxillofacial attention.<br /> <br /> One-hundred-and-five patient records were obtained and analyzed using the SPSS statistic package. One-hundred-and-twenty-seven fractures were recorded in one hundred and five patients. The age of the patients ranged from one to thirteen. Sixty-five male and forty female patients were seen. Dentoalveolar fractures were the most common fracture seen in both the midface and mandible. Midface fractures were more common than mandibular fractures. Falls, followed by motor vehicle accidents, were the most common cause of facial fractures. Most fractures were successfully managed by closed procedures. At this institution, nasal and frontal fractures have surprisingly little or no input from the Department of Oral and Maxillofacial Surgery.

Component-based automatic face recognition has been of interest to a growing number of researchers in the past fifteen years. However, the main challenge remains the automatic extraction of facial components for recognition in different face orientations without any human intervention; or any assumption on the location of these components. In this work, we investigate a solution to this problem. Facial components: eyes, nose, and mouth are firstly detected in different orientations of face. To ensure that the components detected are appropriate for recognition, the Support Vector Machine (SVM) classifer is applied to identify facial components that have been accurately detected. Thereafter, features are extracted from the correctly detected components by Gabor Filters and Zernike Moments combined. Gabor Filters are used to extract the texture characteristics of the eyes and Zernike Moments are applied to compute the shape characteristics of the nose and the mouth. The texture and the shape features are concatenated and normalized to build the final feature vector of the input face image. Experiments show that our feature extraction strategy is robust, it also provides a more compact representation of face images and achieves an average recognition rate of 95% in different face orientations. / Thesis (M.Sc.)-University of KwaZulu-Natal, 2008.

Understanding how human and animal visual systems work is an important and still largely unsolved problem. The neural mechanisms for low-level visual processing have been studied in detail, focusing on early visual areas. Much less is known about the neural basis of high-level perception, particularly in humans. An important issue is whether and how lessons learned from low-level studies, such as how neurons in the primary visual cortex respond to oriented edges, can be applied to understanding highlevel perception, such as human processing of faces. Visual aftereffects are a useful tool for investigating how stimuli are represented, because they reveal aspects of the underlying neural organisation. This thesis focuses on identifying neural mechanisms involved in high-level visual processing, by studying the relationship between low- and high-level visual aftereffects. Previous psychophysical studies have shown that humans exhibit reliable orientation (tilt) aftereffects, wherein prolonged exposure to an oriented visual pattern systematically biases perception of other orientations. Humans also show face identity aftereffects, wherein prolonged exposure to one face systematically biases perception of other faces. Despite these apparent similarities, previous studies have argued that the two effects reflect different mechanisms, in part because tilt aftereffects show a characteristic S-shaped curve, with the effect magnitude increasing and then decreasing with orientation difference, while face aftereffects appeared to increase monotonically (in various units of face morphing strengths) with difference from a norm (average) face. Using computational models of orientation and face processing in the visual cortex, I show that the same computational mechanisms derived from early cortical processing, applied to either orientation-selective or face-selective neurons, are sufficient to replicate both types of effects. However, the models predict that face aftereffects would also be S-shaped, if tested on a sufficiently wide range of face stimuli. Based on the modelling work, I designed psychophysical experiments to test this theory. An identical experimental paradigm was used to test both face gender and tilt aftereffects, with strikingly similar S-shape curves obtained for both conditions. Combined with the modelling results, this result provides evidence that low- and high level visual adaptation reflect similar neural mechanisms. Other psychophysical experiments have recently shown interactions between low and high-level aftereffects, whereby orientation and line curvature processing (in early visual area) can influence judgements of facial emotion (by high-level face-selective neurons). An extended multi-level version of the face processing model replicates this interaction across levels, but again predicts that the cross-level effects will show similar S-shaped aftereffect curves. Future psychophysical experiments can test these predictions. Together, these results help us to understand how stimuli are represented and processed at each level of the visual cortex. They suggest that similar adaptation mechanisms may underlie both high-level and low-level visual processing, which would allow us to apply much of what we know from low-level studies to help understand high-level processing.

This thesis describes a series of empirical studies about perceptions of trustworthiness and trusting behaviour. My first three studies investigate how perceptions of trustworthiness are related to both general preferences for sexually dimorphic face characteristics and individual differences in these preferences. My first study (Chapter 2) provided evidence against a simplistic 'halo-effect' view of the relationship between attractiveness and trustworthiness. The next two studies (Chapters 3 and 4) clarified the role of perceptions of trustworthiness in individual differences in women’s preferences for sexually dimorphic cues in men’s faces; while perceptions of trustworthiness did not explain condition-dependent individual differences (Chapter 3), they were implicated in temporal context-dependent preferences, such as when women assessed men’s attractiveness for long-term relationships (Chapter 4). My next two studies examined perceptions of trustworthiness in different contexts. The first of these studies demonstrated that different individuals are more likely to be trusted according to the type of information that they are conveying (Chapter 5); men are more likely to be trusted when delivering male-stereotyped information and women are more likely to be trusted when delivering female-stereotyped information. The last of my studies (Chapter 6) demonstrated how own appearance affects trusting behaviour in an economic game; the extent to which participants trusted game partners who could see them more than game partners who could not see them was positively related to their other-rated attractiveness. Collectively, the findings reported in this thesis demonstrate the relationship between perceptions of attractiveness and perceptions of trustworthiness, highlighting the complexity and sophistication of the perception of these fundamental social characteristics.

The main focus of this investigation was to examine the automaticity of facial expression recognition through valence judgments in a modified photo-word Stroop paradigm. Positive and negative words were superimposed across male and female faces expressing positive (happy) and negative (angry, sad) emotions. Subjects categorized the valence of each stimulus. Gender biases in judgments of expressions (better recognition for male angry and female sad expressions) and the valence hypothesis of hemispheric advantages for emotions (left hemisphere: positive; right hemisphere: negative) were also examined. Four major findings emerged. First, the valence of expressions was processed automatically (robust interference effects). Second, male faces interfered with processing the valence of words. Third, no posers' gender biases were indicated. Finally, the emotionality of facial expressions and words was processed similarly by both hemispheres.

Master of Science / Department of Apparel, Textiles, and Interior Design / Joy Kozar / China is the world’s largest apparel producer, exporter, and maintains the largest domestic apparel market. Since economic reform in the 1980s that opened up the Chinese market for foreign investors, China’s domestic apparel market has attracted many foreign (Western) apparel brands (Shenkar, 2005). More than 10,000 different international apparel brands share China’s domestic apparel market, including brands from France, Germany, Italy, Japan, the United States, Britain, and South Korea, among others. Around 2,000 Chinese domestic apparel brands have experienced difficultly surviving in China’s domestic apparel market. Besides the large number of foreign (Western) apparel brands, counterfeit apparel products have grown faster than China’s government can control. As a result, China has become the world’s largest counterfeit market. This has become a secondary threat to China’s domestic apparel market and national economy. Additionally, because of economic growth and modernization in China, Chinese consumers have accepted more Westernized values, but also retained their traditional face-saving values. Therefore, the purpose of this study is to explore how their attitudes toward counterfeit apparel products, China’s domestic apparel brands, and foreign (Western) apparel brands are influenced by their level of perception about knowledge and attitudes toward counterfeit apparel products, face-saving values, materialistic values, and ethical values. This study utilized a sample of males and females between the ages of 18 and 64, who reside in Guangzhou, Shanghai, Chengdu, and Wuhan, China. A questionnaire was utilized as part of this study and data was collected online by SOJUMP Survey Company. A total of 1,192 participants (736 males and 456 females) participated in this study. There are in total nine significant relationships that have been found in this study. First, the researcher found a positive relationship between Chinese consumers’ perception about knowledge of counterfeit apparel products and their attitudes about counterfeit apparel products. Second and third, the present study also discovered that Chinese consumers with favorable attitudes of foreign apparel brands or negative attitude of China’s domestic apparel brands would similarly hold positive attitudes of counterfeit apparel products. Fourth, the present scholar concluded that Chinese consumers with favorable attitudes of China’s domestic apparel brands tend to hold negative attitudes of counterfeit apparel products. Fifth and sixth, it was found that Chinese consumers with high level of face-saving values show positive attitudes of foreign (Western) apparel brands and counterfeit apparel products. Seventh, Chinese consumers with high level of face-saving values also possess strong materialistic values. Consequently Chinese consumers with strong materialistic values tend to hold positive attitudes of counterfeit apparel products and foreign (Western) apparel products, but negative attitudes of China’s domestic apparel brands. The findings of this study show that Chinese consumers have a very low level of perception about knowledge of counterfeit apparel products. It is necessary to connect educators, government, apparel industry, and brand owners to develop and enhance anti-counterfeit educational programs. These programs should clearly explain the perception about knowledge of Intellectual Property Rights (IPR), trademark, and the negative causes of counterfeit products are warranted. Also, it is better for China’s domestic apparel brand companies to develop better brand images and improve product quality to meet Chinese consumers’ face-saving standards and materialistic values.

Potential impacts of climate change on grain sorghum (Sorghum bicolor) productivity were investigated using the CERES-sorghum model in the Decision Support System for Agrotechnology Transfer v4.5. The model was first calibrated for a sorghum cultivar grown in a free air CO2 enrichment experiment at the University of Arizona, Maricopa, Arizona, USA in 1998. The model was then validated with an independent dataset collected in 1999. The simulated grain yield, growth, and soil water of sorghum for the both years were in statistical agreement with the corresponding measurements, respectively. Neither simulated nor measured yields responded to elevated CO2, but both were sensitive to water supply. The validated model was then applied to simulate possible effects of climate change on sorghum grain yield and water use efficiency in western North America for the years 2080-2100. The projected CO2 fertilizer effect on grain yield was dominated by the adverse effect of projected temperature increases. Therefore, temperature appears to be a dominant driver of the global climate change influencing future sorghum productivity. These results suggest that an increase in water demand for sorghum production should be anticipated in a future high-CO2 world.

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This thesis discusses cognitive processes theories with special emphasis on those affecting recognition and identification of human faces, introduces the issue of eyewitness testimony and the issue of methods and techniques of criminal identification proven in forensic science and actually in use in police work. The literature and previous empirical studies dealing with the issue of line-up and show-up reliability and accuracy are reviewed afterwards. The effect of selected variables, i.e. retention interval and similarity of suspect clothing, within the show-up and line-up procedures is well mentioned. Experiments in this thesis examine these interrelated goals: determining the effect of two variables on show up accuracy as well as the suggestivity of show up method and exploring carryover effect from show up to line up identification procedure. Keywords: cognitive processes, facial recognition, individual identification, eyewitness testimony