Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 71-75).

Thesis (M.Sc.)--York University, 2008. Graduate Programme in Higher Education. / Typescript. Includes bibliographical references. Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR45975

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 59-63).

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (p. 124-140).

Thesis (M.A.)--York University, 2008. Graduate Programme in Psychology. / Typescript. Includes bibliographical references (leaves 72-94). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR45951

published_or_final_version / Clinical Psychology / Master / Master of Social Sciences

published_or_final_version / Psychology / Master / Master of Philosophy

published_or_final_version / Anaesthesiology / Doctoral / Doctor of Philosophy

Previous bilingual studies showed reduced hemispheric asymmetry in visual tasks such as face perception in bilinguals compared with monolinguals, which suggested that hemispheric asymmetry in visual tasks could be modulated by experience in reading one or two languages. Here I examined whether differences in hemispheric asymmetry in visual tasks can also be observed in bilinguals who have different language backgrounds. I compared the behavior of three language groups: (1) English monolinguals, who acquire only one alphabetic language, (2) European-English bilinguals, who know two alphabetic languages, and (3) Chinese-English bilinguals, who master an alphabetic language and a logographic language; in three tachistoscopic tasks: (1) English word sequential matching task, (2) Intact-altered face judgment task, and (3) face sequential matching task. The results showed that European-English bilinguals had a stronger right visual field (RVF)/ left hemispheric (LH) advantage in the English word sequential matching task than English monolinguals and Chinese-English bilinguals, suggesting that different language learning experiences can influence how visual words are processed in the brain. However, the results showed no group difference between the left visual field (LVF)/ right hemisphere (RH) advantage in the intact-altered face judgment task and the face sequential matching task. These results suggested a modulation of language experience on visual word processing but not on face processing. In addition, I showed that the hemispheric asymmetry in visual word processing could be accounted for by a computational model that implements a theory of hemispheric asymmetry in perception (i.e. the Double Filtering by Frequency theory, Ivry & Robertson, 1998); the modeling data suggested that this lateralization difference in visual word processing may be due to both the difference in participants’ vocabulary size and the difference in word-to-sound mapping between alphabetic and logographic languages. / published_or_final_version / Psychology / Master / Master of Philosophy

Visual working memory (VWM) has long been considered to be limited in capacity, but the way in which it is limited remains unclear. One of the theoretical debates in visual working memory concerns whether the number of objects that can be stored is fixed (discrete slot models) or variable (flexible resource models). Recent research on the resolution of VWM has helped elucidate this debate by acknowledging an important trade-off between number and resolution: as the number of items stored increases, the resolution of representation declines. Yet, a different conception suggests that the number and resolution may represent distinct aspects of visual working memory, evidenced by both behavioral and neuroimaging data. In this thesis, I examined three theoretical questions regarding the relationship between the number and the resolution of items in VWM. First, how does set size affect high- & low-resolution representations (differentially)? If an item limit can be evidenced in the high-resolution measure, but not in the low-resolution measure, my second research question emerges. That is, how much resolution do we have for the remaining objects when the item limit is exceeded? Third, if both high- & low-resolution representations of an item exist in VWM, are they stored together or independently? In a series of five experiments, I addressed these questions using an adapted continuous report paradigm, in which participants were asked to remember a mixture of objects from two categories and respond firstly to the category of the item-to-report (low-resolution measure), followed by a second within-category response (high-resolution measure) which was contingent on the first. In Experiments 1-2, only performance in the low-resolution, but not in the high-resolution, measure was largely indifferent to set size, which was not compatible with either discrete slot or flexible resource models, but was largely consistent with predictions from the two-factor model and the neural object-file theory. In Experiments 3-4, precision of high-resolution representations declined monotonically until the set size reached around four items, fitting to the predictions from discrete slot models. The overall accuracy in low-resolution measure, however, remained relatively high, suggesting differential set size influence on high- and low-resolution representations. In Experiment 5, capacity comparison revealed no significant difference when the low-resolution task was absent. Taken together, I demonstrate that 1) both low-resolution ensemble representations and high-resolution individual item representations exist in VWM, and 2) high-resolution representations (i.e. object identity) and low-resolution representations (i.e. objects’ categories, configural information and perhaps some coarse feature information) of an object might be stored independently. / published_or_final_version / Psychology / Master / Master of Philosophy