Document Detail

Second-order optic flow processing.
MedLine Citation:
PMID:  17462696     Owner:  NLM     Status:  MEDLINE    
Optic flow-large-field rotational and radial motion-is processed as efficiently as translational motion for first-order (luminance-defined) stimuli. However, it has been suggested recently that the same pattern does not hold for second-order (e.g. contrast-defined) stimuli. We used random dot kinematogram (RDK) stimuli to determine whether global processing of optic flow is as efficient as processing of global translational motion for both first- and second-order stimuli. For first-order stimuli, we found that coherence thresholds for radial and rotational motion were equivalent to thresholds for translational motion, supporting previous findings. For second-order stimuli we found, firstly, that given sufficient contrast, second-order optic flow can be processed as efficiently as first-order optic flow and, secondly, that rotational and translational second-order motion are processed with equal efficiency. This contradicts the suggestion that there is a loss of efficiency between integration of second-order global motion and second-order optic flow. The third interesting finding was that the processing of radial second-order motion appears to suffer from a deficit that is dependent upon both the contrast and spatial extent of the stimulus. Further experiments discounted the possibility that the observed deficit is caused by a centrifugal or centripetal bias, but demonstrated that a longer temporal integration period for radial second-order motion is responsible for the observed difference. For durations of approximately 850ms, all three types of motion are processed with equal efficiency.
Craig Aaen-Stockdale; Tim Ledgeway; Robert F Hess
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Publication Detail:
Type:  Journal Article     Date:  2007-04-25
Journal Detail:
Title:  Vision research     Volume:  47     ISSN:  0042-6989     ISO Abbreviation:  Vision Res.     Publication Date:  2007 Jun 
Date Detail:
Created Date:  2007-05-22     Completed Date:  2007-08-10     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0417402     Medline TA:  Vision Res     Country:  England    
Other Details:
Languages:  eng     Pagination:  1798-808     Citation Subset:  IM    
Department of Ophthalmology, McGill Vision Research, McGill University, Royal Victoria Hospital, 687 Pine Ave West, Rm H4-14, Montreal, Que., Canada H3A 1A1.
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MeSH Terms
Contrast Sensitivity
Depth Perception
Motion Perception*
Photic Stimulation / methods
Sensory Thresholds
Space Perception
Time Factors

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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