Dissertation Information for Yili Liu
MPACT Status: Incomplete - Not_Inspected
Title: Effects of spatial uncertainty in visual scanning on divided and selective attention and multi-task performance
Abstract: The objective of this study is to address the relation between single channel theories of selective attention and the multiple resource theory of divided attention by examining the relation of visual scanning as a sequential and selective attention process to other concurrent spatial or verbal tasks. A distinction is proposed between visual scanning with or without spatial uncertainty regarding the possible differential effects of these two types of scanning on interference with other concurrent processes. It is proposed that visual scanning without spatial uncertainty will only produce peripheral interference, whereas scanning with spatial uncertainty will produce central as well as peripheral interference. An experiment was conducted to test this hypothesis. The experiment required the subject to perform a primary tracking task, which was time-shared with a secondary spatial or verbal decision task. The relevant information that was needed to perform the decision tasks were displayed with or without spatial uncertainty. The experiment employed a 2 x 2 x 2 design with types of scanning (with or without spatial uncertainty), expected scanning distance (short/long) and codes of concurrent processing (spatial/verbal) as the three experimental factors. The results provide evidence that visual scanning as a spatial exploratory activity produces greater task interference with concurrent spatial tasks than with concurrent verbal tasks, as predicted by the multiple resource theory. Furthermore, spatial uncertainty in visual scanning is identified to be the crucial factor in producing this differential effect. An analysis of additive factors also showed a close fit between the current data and the data that would be predicted by results of previous eye movement studies and single channel assumptions. Theoretical and practical implications of these results are discussed.
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