Effects of Perceptual and Working Memory Load on Neural Responses to Task-Relevant and Irrelevant Visual Stimuli

Oscar Jacoby (2010). Effects of Perceptual and Working Memory Load on Neural Responses to Task-Relevant and Irrelevant Visual Stimuli Honours Thesis, School of Psychology, The University of Queensland.

       
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Author Oscar Jacoby
Thesis Title Effects of Perceptual and Working Memory Load on Neural Responses to Task-Relevant and Irrelevant Visual Stimuli
School, Centre or Institute School of Psychology
Institution The University of Queensland
Publication date 2010
Thesis type Honours Thesis
Total pages 99
Abstract/Summary To help us efficiently negotiate our environment and accomplish our goals, our brains selectively enhance the processing of stimuli relevant to our current task, and suppress the processing of irrelevant stimuli. Our ability to selectively process only task-relevant stimuli – referred to as selective attention – can be affected by the perceptual demands of the task being performed, and by demands on working memory. This thesis investigated the role of perceptual and working memory load on selective attention during visual search through a rapidly changing visual display. Predictions about the effects of perceptual and working memory load on stimulus processing were made on the basis of the load theory of selective attention (Lavie, Hirst, Viding, & Fockert, 2004). In two experiments, participants searched for target items within streams of centrally presented letters and digits, while task- irrelevant checkerboard stimuli flickered in the periphery. We simultaneously measured the strength of neural responses to the task-relevant central stimuli and the irrelevant checkerboard stimuli using scalp-recorded electroencephalography (EEG). Increasing the perceptual demands of the central task reduced EEG activity associated with the task-relevant search items, but had no effect on EEG activity associated with the irrelevant checkerboard stimuli. Increasing working memory load yielded a similar pattern of results. Comparing these findings to those of previous studies suggests a number of additional factors which may modulate the effects of task load on stimulus processing. Future research should investigate the roles of these factors in modulating the relationships between perceptual load, working memory load, and selective attention.

 
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Created: Mon, 04 Apr 2011, 15:14:38 EST by Lucy O'Brien on behalf of School of Psychology