Linked Life Data

10958913

Source:http://linkedlifedata.com/resource/pubmed/id/10958913

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
19
pubmed:dateCreated
2000-9-15
pubmed:abstractText
We investigated human sensitivity to vertical mirror symmetry in noise patterns filtered for narrow bands of variable orientations. Sensitivity is defined here as the amount of spatial phase randomization corresponding to 75% correct performance in a 2AFC detection task. In Experiment 1, sensitivity was found to be high for tests patterns of all orientations except those parallel to the axis of symmetry. This implies that corresponding mirror-orientations (e.g. -45 and +45 degrees ) are combined prior to symmetry detection. In Experiment 2, observers detected symmetry in tests of variable orientation in the presence of either non-symmetric or symmetric masks filtered for orientations either parallel or perpendicular to the axis. Observers were found to be primarily affected by masks of the same orientation as the test, thus suggesting that symmetry is computed separately in distinct mirror-orientation channels. In Experiment 3, observers detected a symmetric test of variable height and width embedded in random noise. Data revealed that mirror symmetry is computed over a spatial integration region (IR) that remains approximately constant in area but whose height-to-width aspect ratio changes from 20:1 to 2:1 as orientation is varied from parallel to perpendicular to the axis. We compare human data against that of an ideal observer to identify key factors that limit visual performance and discuss the implications for the functional architecture of symmetry perception. We also propose a multi-channel model of symmetry detection that combines the output of oriented spatial filters in a simple and physiologically plausible manner. Particular emphasis is placed on the notion that changes in the shape of the IR with orientation compensate for changes in information density and partially equate performance across orientations.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:status
MEDLINE
pubmed:issn
0042-6989
pubmed:author
pubmed:issnType
Print
pubmed:volume
40
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2621-44
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
2000
pubmed:articleTitle
The functional role of oriented spatial filters in the perception of mirror symmetry--psychophysics and modeling.
pubmed:affiliation
McGill Vision Research Unit, Room H4-14, 687 Pine Ave W., Québec, H3A 1A1, Montréal, Canada. stephane@cvs.rochester.edu
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't