| Evidence for an attentional component of the perceptual misalignment between moving and flashing stimuli. | |
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MedLine Citation:
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PMID: 11971260 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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If a pair of dots, diametrically opposed to each other, is flashed in perfect alignment with another pair of dots rotating about the visual fixation point, most observers perceive the rotating dots as being ahead of the flashing dots (flash-lag effect). This psychophysical effect was first interpreted as the result of a perceptual extrapolation of the position of the moving dots. Also, it has been conceived as the result of differential visual latencies between flashing and moving stimuli, arising from purely sensory factors and/or expressing the contribution of attentional mechanisms as well. In a series of two experiments, we had observers judge the relative position between rotating and static dots at the moment a temporal marker was presented in the visual field. In experiment 1 we manipulated the nature of the temporal marker used to prompt the alignment judgment. This resulted in three main findings: (i) the flash-lag effect was observed to depend on the visual eccentricity of the flashing dots; (ii) the magnitude of the flash-lag effect was not dependent on the offset of the flashing dot; and (iii) the moving stimulus, when suddenly turned off, was perceived as lagging behind its disappearance location. Taken altogether, these results suggest that neither visible persistence nor motion extrapolation can account for the perceptual flash-lag phenomenon. The participation of attentional mechanisms was investigated in experiment 2, where the magnitude of the flash-lag effect was measured under both higher and lower predictability of the location of the flashing dot. Since the magnitude of the flash-lag effect significantly increased with decreasing predictability, we conclude that the observer's attentional set can modulate the differential latencies determining this perceptual effect. The flash-lag phenomenon can thus be conceived as arising from differential visual latencies which are determined not only by the physical attributes of the stimulus, such as its luminance or eccentricity, but also by attentional mechanisms influencing the delays involved in the perceptual processing. |
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Authors:
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Marcus V C Baldo; Alexandre H Kihara; Janaina Namba; Stanley A Klein |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Perception Volume: 31 ISSN: 0301-0066 ISO Abbreviation: Perception Publication Date: 2002 |
Date Detail:
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Created Date: 2002-03-29 Completed Date: 2002-05-29 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0372307 Medline TA: Perception Country: England |
Other Details:
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Languages: eng Pagination: 17-30 Citation Subset: IM |
Affiliation:
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Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, SP, Brazil. baldo@fisio.icb.usp.br |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adult Attention* Humans Models, Psychological Motion Perception* Optical Illusions* Photic Stimulation / methods Reaction Time Rotation Space Perception* |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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