Selective attention is a filtering system that focuses on relevant information in our environment while irrelevant information is suppressed. The two well-known components of selective attention, facilitation and inhibition, work hand in hand to aid the processing of relevant information. The main theme of the present thesis was to study the inhibitory component of visual selective attention using stimuli such as motion and shape in a rapid serial visual presentation. Therefore, the first three experimental chapters investigated how relevant motion and shape information are processed and perceived in the presence of similar irrelevant information. The findings showed that first order visual motion detection is impaired in the presence of distracters and this inhibition of distracters is generated in a bottom-up manner. The findings were, however, not straightforward. The findings from Experiments 6-10 showed that distracter information (shape) influences shape target detection only when distracters are made salient and the perceptual load of the task is moderately difficult. Collectively, the findings in this present thesis suggest that there may be more than one kind of inhibition generated for different kinds of stimuli.

Call number: LD2668 .T4 1959 P37

Healthy ageing in the absence of neurodegenerative diseases is accompanied by a variety of perceptual and cognitive changes, which can occur on various distinct but interacting levels. Much research has been devoted to understanding how basic cognitive functions such as working memory and attention change with age. However, only more recently has age-related changes on perceptual functions been investigated, thus less is understood. My thesis aimed to address this gap in the literature, by exploring age-related changes in visual perception, specifically changes related to visual temporal processing of natural and biological stimuli. Also investigated was the extent to which age-related changes in perceptual and cognitive functions affect each other. Chapter 2 investigated the time course of visual processing of natural scene categorisation in older adults. Younger, young-old and old-old adults performed a go/no-go task, in which they had to respond to images of animals whilst ignoring images of landscapes. The results showed that the temporal processing of complex scenes is impaired in healthy older adults and this deficit becomes more pronounced with increasing age. Chapter 3 assessed whether age-related decline in biological motion perception is mediated by impaired attentional abilities. Younger and older adults performed a series of tasks assessing biological motion perception and visual attention. The results indicated that age-related changes in biological motion perception are not driven by general attentional decline. Lastly, Chapter 4 explored whether age-related changes in biological motion and attention tasks can be explained by differences in the allocation of attention. Younger and older adults performed a conjunctive visual search, and two biological motion tasks, while their eye movements were being tracked. The results illustrated that differences in the allocation of attention cannot explain age-related differences found on biological motion perception and attention tasks. Overall, my findings provide substantial evidence to suggest that both visual perceptual and cognitive abilities change with healthy ageing. However, my results also indicate that certain aspects of these two functions remain relatively preserved in older adulthood.

Thesis. 1976. M.S.--Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics. / Microfiche copy available in Archives and Barker. / Bibliography: p.101-102. / M.S.

Thesis (Ph. D.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.

The processes underlying the perceptual analysis of visual form are believed to have minimal interaction with those subserving the perception of visual motion (Livingstone and Hubel, 1987; Victor and Conte, 1990). Recent reports of functionally and anatomically segregated parallel streams in the primate visual cortex seem to support this hypothesis (Ungerlieder and Mishkin, 1982; VanEssen and Maunsell, 1983; Shipp and Zeki, 1985; Zeki and Shipp, 1988; De Yoe et al., 1994). Here we present perceptual evidence that is at odds with this view and instead suggests strong symmetric interactions between the form and motion processes. In one direction, we show that the introduction of specific static figural elements, say 'F', in a simple motion sequence biases an observer to perceive a particular motion field, say 'M'. In the reverse direction, the imposition of the same motion field 'M' on the original sequence leads the observer to perceive illusory static figural elements 'F'. A specific implication of these findings concerns the possible existence of (what we call) motion end-stopped units in the primate visual system. Such units might constitute part of a mechanism for signalling subjective occluding contours based on motion-field discontinuities.

Thesis (Ph.D.)--York University, 2004. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 292-305). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pNQ99265

Thesis (Ph. D.)--University of California, San Diego, and San Diego State University, 2004. / Vita. Includes bibliographical references.

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 California, San Diego and San Diego State University, 2003. / Vita. Includes bibliographical references (leaves 182-208).