Thesis (MA(Psychology))-University of Pretoria, 2008. / Includes bibliographical references.

Thesis (M.Sc.)--York University, 2004. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 59-66). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pMQ99314

Thesis (Ph.D.)--McMaster University, 2003. / Includes bibliographical references (p. 87-97) Also available via World Wide Web.

Thesis (Ph.D.)--University of Texas at Dallas, 2007. / Includes vita. Includes bibliographical references (leaves 95-100)

Thesis (Ph.D.)--University of Texas at Dallas, 2007. / Includes vita. Includes bibliographical references (leaves 64-68)

[Truncated abstract] Recent studies have provided evidence that face-coding mechanisms reference a norm or average face (Leopold, O`Toole, Vetter & Blanz, 2001; Rhodes & Jeffery, 2006). The central aim of this thesis was to establish whether distinct norms, and dissociable neural mechanisms code faces of different race and sex categories. Chapter 1 provides a brief introduction to norm based coding of faces, and reviews evidence for the existence of distinct norms for different races and sexes. Chapter 1 then introduces adaptation as a tool for investigating these ideas. Chapter 2 presents two adaptation studies that examined how faces of different races are coded. The aim of these studies was to determine whether dissociable neural mechanisms (or distinct face norms) code faces of different races. Chinese and Caucasian participants rated the normality of Caucasian and Chinese test faces, before and after adaptation to distorted faces of one race (e.g., 'contracted' Chinese faces; Experiment 1) or distorted faces of both races (e.g., 'contracted' Chinese faces and 'expanded' Caucasian faces; Experiment 2). Following adaptation to faces of one race, there were changes in perceived normality for faces of both races (i.e., perceptual aftereffects), indicating that common neural mechanisms code Chinese and Caucasian faces. However, aftereffects were significantly smaller in faces of the unadapted race suggesting some sensitivity to the race of faces. This sensitivity was also evident in Experiment 2. ... Some dissociability was also found in the coding of faces of different iv sexes. In Experiments 2 and 3, participants adapted to oppositely distorted faces of both sexes. Weak sex-selective aftereffects were found. Taken together, the findings suggest that male and female faces are coded by dissociable but not completely distinct neural populations. Chapter 4 examined whether the aftereffects reported for faces of different races or sexes reflected the adaptation of high-level neural mechanisms tuned to the social category information in faces, or earlier coding mechanisms tuned to simple physical differences between face groups. Chinese and Caucasian participants adapted to oppositely distorted face sets that were the same distance apart on a morph continua. The face sets were either from different race categories (e.g., contracted Chinese faces and expanded Caucasian faces), or from the same race category, (e.g., contracted Chinese faces and expanded caricatured Chinese faces). Larger opposite aftereffects were found when face sets were from different race categories, than when they were from the same race category suggesting that oppositely adapted neural mechanisms are tuned to social category differences rather than simple physical differences in faces. Together, these studies shed new light on how we code faces from different face categories. Specifically, the findings indicate that faces of different races and sexes are coded by both common and race- or sex-selective neural mechanisms. In addition, the findings are consistent with the possibility that race- and sex-selective norms and dimensions are used to code faces in face space. The implications of these findings and possible avenues for future research are discussed.

Thesis (Ph. D.)--University of California, San Diego, 2007. / Title from first page of PDF file (viewed January 14, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references. Faces are central stimuli in our everyday life, hence, face processing is a sophisticated and highly specialized cognitive ability, at which adults are experts and children are proficient. Unlike other visuospatial abilities, face perception develops very slowly, becoming adult-like only well into adolescence. Some performance disparities between children and adults may reflect differences in general cognitive abilities, such as attention and memory. Alternatively, performance differences can be attributed to specific cognitive strategies implemented during face processing by different age groups; or to the interaction between the improvement of general abilities throughout development and the refinement of face specific cognitive strategies. The intent of the current studies was to further assess the development of and relationship between cognitive strategies in face processing. Specifically, we investigated the behavior and neurocorrelates associated with holistic face processing in children (8- to 11-year-olds), adolescents, and adults, utilizing the composite face effect. The task requires participants to engage in both holistic and featural processing, but certain trials (aligned-same) elicit a visual illusion called the composite face effect (CFE, calculated as difference between misaligned-same and aligned-same trials), which is considered an index of holistic processing. All age groups (adults, adolescents, 8- to 9-year-olds, 10- to 11-year-olds) showed a CFE, suggesting reliance on holistic processing. Notably, about half of the 8- to 11-year-old children displayed adult-like behavior and adult-like CFE, suggesting their reliance on holistic processing. However, the other half of the children performed below-chance on aligned-same trials, displayed an extremely large CFE, and a significant difference between different trials, suggesting reliance on a featural strategy. Thus child age groups were regrouped according to their accuracy performance on the hardest condition (aligned-same trials) into high performing and low performing children. We hypothesize that the aligned-same trials were too taxing for low-performing children, thus they fell back into relying on simpler strategies such as a difference-detection featural strategy. In order to further investigate the CFE behavioral differences between age and performance groups, we completed an imaging study. For the fMRI study children were grouped by performance rather than age following the results of our behavioral study. Overall, our imaging results for the CFE, thus for holistic processing, resembled behavioral results in that adult and high performing child groups revealed a similar (but not identical) whole-brain pattern of activation, whereas the low performing child group showed a distinctive pattern of activation for the composite face effect. Adults and high performing children showed a pattern of activation spanning frontal, parietal, temporal, and occipital lobes. In contrast, low performing children revealed a pattern of activation that spanned frontal, temporal, cingulate, and cerebellar regions. Brain areas typically associated with face processing, such as the right fusiform gyrus and right inferior temporal gyrus did not reach significance for the low performing child group. These differences may be attributable to the use of different cognitive strategies. However, the extent of frontal and cingulate cortex activation in low performing children may also suggest that because the task was especially difficult for them, working memory resources were particularly taxed, thus affecting the neural network engaged. Importantly, not only were performance differences associated with distinct neurocorrelates (i.e., differing profiles for low performing children vs. high performing children and adults), but age differences also had an appreciable effect. In fact, high performing children did not significantly differ from adults in the behavioral CFE, but did show differences in the neural CFE.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Matching unfamiliar faces is known to be a very difficult task. Yet, despite this, we frequently rely on this method to verify people's identity in high security situations, such as at the airport. Because of such security implications, recent research has focussed on investigating methods to improve our ability to match unfamiliar faces. This has involved methods for improving the document itself, such that photographic-ID presents a better representation of an individual, or training matchers to be better at the task. However, to date, no method has demonstrated significant improvements that would allow the technique to be put into practice in the real world. The experiments in this thesis therefore further explore methods to improve unfamiliar face matching. In the first two chapters both variability and feedback are examined to determine if these previously used techniques do produce reliable improvements. Results show that variability is only of use when training to learn a specific identity, and feedback only leads to improvements when the task is difficult. In the final chapter, collaboration is explored as a new method for improving unfamiliar face matching in general. Asking two people to perform the task together did produce consistent accuracy improvements, and importantly, also demonstrated individual training benefits. Overall, the results further demonstrate that unfamiliar face matching is difficult, and although finding methods to improve this is not straightforward, collaboration does appear to be successful and worth exploring further. The findings are discussed in relation to previous attempts at improving unfamiliar face matching, and the effect these may have on real world applications.

Qu, Zhiyi. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 110-118). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.