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The detection of multiple global directions: Capacity limits with spatially segregated and transparent-motion signals

Greenwood, John; Edwards, Mark

Description

An important constraint on motion processing is the maximum number of directions that can be perceived at the same time. When transparent-motion stimuli are constructed based solely on direction differences, prior studies demonstrate that no more than two directions are seen simultaneously. However, this limit has been extended to three when signal directions drive independent speed- or disparity-tuned global-motion systems. The present study sought to determine whether this three-direction...[Show more]

dc.contributor.authorGreenwood, John
dc.contributor.authorEdwards, Mark
dc.date.accessioned2015-12-08T22:45:01Z
dc.date.available2015-12-08T22:45:01Z
dc.identifier.issn1534-7362
dc.identifier.urihttp://hdl.handle.net/1885/37652
dc.description.abstractAn important constraint on motion processing is the maximum number of directions that can be perceived at the same time. When transparent-motion stimuli are constructed based solely on direction differences, prior studies demonstrate that no more than two directions are seen simultaneously. However, this limit has been extended to three when signal directions drive independent speed- or disparity-tuned global-motion systems. The present study sought to determine whether this three-direction capacity reflects the specific mechanisms of transparent-motion detection or a more general restriction on global-motion processing. Using both transparent and spatially segregated stimuli, observers indicated which of the two intervals contained the most directions, with simultaneous processing ensured through brief durations and n vs. n + 1 signal comparisons. When spatially segregated directions were interleaved in patches, no more than two were seen, as with direction-defined transparent motion. In contrast, separating these directions into distinct spatial regions allowed the detection of up to three. Signal-detection thresholds did not vary across these signal arrangements, suggesting that the two-direction capacity results from signal-to-noise pooling across the entire stimulus, with the higher capacity for spatially distinct directions arising from independent pooling within each region. Together, these results provide further evidence for an upper capacity of three directions within the global-motion stage.
dc.publisherAssociation for Research in Vision and Opthalmology
dc.sourceJournal of Vision
dc.subjectKeywords: adult; article; attention; depth perception; differential threshold; human; male; methodology; movement perception; perceptive discrimination; photostimulation; Adult; Attention; Differential Threshold; Humans; Male; Motion Perception; Photic Stimulation; Attention; Capacity limit; Global motion; Motion perception; Transparency
dc.titleThe detection of multiple global directions: Capacity limits with spatially segregated and transparent-motion signals
dc.typeJournal article
local.description.notesImported from ARIES
local.identifier.citationvolume9
dc.date.issued2009
local.identifier.absfor170112 - Sensory Processes, Perception and Performance
local.identifier.ariespublicationu9312950xPUB151
local.type.statusPublished Version
local.contributor.affiliationGreenwood, John, College of Medicine, Biology and Environment, ANU
local.contributor.affiliationEdwards, Mark, College of Medicine, Biology and Environment, ANU
local.bibliographicCitation.issue1:40
local.bibliographicCitation.startpage1
local.bibliographicCitation.lastpage15
local.identifier.doi10.1167/9.1.40
dc.date.updated2016-02-24T11:58:17Z
local.identifier.scopusID2-s2.0-59649090968
local.identifier.thomsonID000264448300040
CollectionsANU Research Publications

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