Perceptual load modulations of spatial and non -spatial visual selection processes: An event -related brain potential study.
Item
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Title
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Perceptual load modulations of spatial and non -spatial visual selection processes: An event -related brain potential study.
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Identifier
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AAI3231953
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identifier
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3231953
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Creator
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Barnhardt, Jack.
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Contributor
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Adviser: Hilary Gomes
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Date
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2006
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Language
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English
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Publisher
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City University of New York.
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Subject
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Psychology, Physiological | Psychology, Cognitive
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Abstract
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The act of paying attention to only a portion of the sensory information that is present is referred to as selective attention. One of the major questions to be answered toward understanding this cognitive mechanism regards the 'locus' of selection---when the selection of this 'relevant' information, and hence the filtering out of irrelevant information, occurs. One theory contends that the locus of selection in vision is determined primarily by the perceptual load (PL) imposed by the relevant stimuli. According to the theory, if this load is relatively high such that attentional capacity is filled, irrelevant stimuli will be filtered early and so will not interfere with task performance. If this load is relatively low, the attentional capacity that remains will be directed automatically to the irrelevant information, even in situations where task interference may result. The current study attempts to test and extend this theory in order to understand better the role of PL. We therefore examined its effects on event-related brain potentials (ERPs)-voltage fluctuations recorded at the scalp that reflect underlying cognitive operations. Participants responded to rare deviant stimuli presented either to a predetermined side of fixation (spatial task) or of a particular color (non-spatial task) while attempting to ignore the other side/color. PL was manipulated by varying the similarity between the deviant and standard stimulus, and was found to modulate the magnitude of the attend---unattend difference waveforms in both the spatial and nonspatial tasks at the predicted latencies. These findings, when considered in light of the fact that no irrelevant information was present when subjects responded to targets as in the interference studies that provide the primary body of support for PL theory, collectively suggest that perceptual load is important not only for preventing attention from being directed to the irrelevant information that is currently present, but also affects attentional selection that is tonically maintained across many experimental trials. The results further suggest that this occurs not only when selection is spatially based as in past studies, but also when it is based upon non-spatial cues. Additions to the existing theory may therefore be warranted.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
