The perceptual contrast of impossible shadow edges

Hdl Handle:
http://hdl.handle.net/10149/94543
Title:
The perceptual contrast of impossible shadow edges
Authors:
Soranzo, A. (Alessandro); Galmonte, A. (Alessandra); Agostini, T. (Tiziano)
Affiliation:
University of Teesside. School of Social Sciences and Law.
Citation:
Soranzo, A., Galmont, A. and Agostini, T. (2009) 'The perceptual contrast of impossible shadow edges', Perception, 38 (2), pp.164–172.
Publisher:
Pion
Journal:
Perception
Issue Date:
Feb-2009
URI:
http://hdl.handle.net/10149/94543
DOI:
10.1068/p5932
Abstract:
Luminance ratios along shadow edges remain the same even when they cross reflectance borders. According to Gilchrist (1988, Perception & Psychophysics 43 415-424) this so-called ratio-invariance property is a crucial factor in the perception of shadows. However, Soranzo and Agostini (2004, Perception 33 1359-1368) suggested that in some conditions (named 'impossible shadows'), a luminance pattern might still be perceived as a shadow even if the ratio-invariance property along its edge is violated. This can occur when an edge is collinear with another edge (contextual edge) which incorporates it, shares the same polarity, and generates a larger ratio. The hypothesis that impossible shadows are actually perceived as shadows is here tested by comparing the perceptual contrast of a luminance edge in the absence of a contextual edge (control condition) to that of both possible shadow edges (where the contextual and mediating edge share the same ratio) and impossible shadow edges (where the ratio of the contextual edge is larger rather than that at the mediating edge). We found that the perceived contrast of luminance edges shrinks in both possible and impossible shadow conditions rather than in the control condition. This evidence supports the hypothesis that a luminance pattern might be perceived as a shadow even when the ratio-invariance property is violated.
Type:
Article
Language:
en
Keywords:
luminance ratios; shadow edges; impossible shadows; luminance pattern; contrast
ISSN:
0301-0066; 1468-4233
Rights:
Subject to restrictions, author can archive post-print (ie final draft post-refereeing). For full details see http://www.sherpa.ac.uk/romeo/ [Accessed 19/03/2010]
Citation Count:
0 [Scopus, 19/03/2010]

Full metadata record

DC FieldValue Language
dc.contributor.authorSoranzo, A. (Alessandro)en
dc.contributor.authorGalmonte, A. (Alessandra)en
dc.contributor.authorAgostini, T. (Tiziano)en
dc.date.accessioned2010-03-19T14:40:11Z-
dc.date.available2010-03-19T14:40:11Z-
dc.date.issued2009-02-
dc.identifier.citationPerception; 38 (2): 164–172en
dc.identifier.issn0301-0066-
dc.identifier.issn1468-4233-
dc.identifier.doi10.1068/p5932-
dc.identifier.urihttp://hdl.handle.net/10149/94543-
dc.description.abstractLuminance ratios along shadow edges remain the same even when they cross reflectance borders. According to Gilchrist (1988, Perception & Psychophysics 43 415-424) this so-called ratio-invariance property is a crucial factor in the perception of shadows. However, Soranzo and Agostini (2004, Perception 33 1359-1368) suggested that in some conditions (named 'impossible shadows'), a luminance pattern might still be perceived as a shadow even if the ratio-invariance property along its edge is violated. This can occur when an edge is collinear with another edge (contextual edge) which incorporates it, shares the same polarity, and generates a larger ratio. The hypothesis that impossible shadows are actually perceived as shadows is here tested by comparing the perceptual contrast of a luminance edge in the absence of a contextual edge (control condition) to that of both possible shadow edges (where the contextual and mediating edge share the same ratio) and impossible shadow edges (where the ratio of the contextual edge is larger rather than that at the mediating edge). We found that the perceived contrast of luminance edges shrinks in both possible and impossible shadow conditions rather than in the control condition. This evidence supports the hypothesis that a luminance pattern might be perceived as a shadow even when the ratio-invariance property is violated.en
dc.language.isoenen
dc.publisherPionen
dc.rightsSubject to restrictions, author can archive post-print (ie final draft post-refereeing). For full details see http://www.sherpa.ac.uk/romeo/ [Accessed 19/03/2010]en
dc.subjectluminance ratiosen
dc.subjectshadow edgesen
dc.subjectimpossible shadowsen
dc.subjectluminance patternen
dc.subjectcontrasten
dc.titleThe perceptual contrast of impossible shadow edgesen
dc.typeArticleen
dc.contributor.departmentUniversity of Teesside. School of Social Sciences and Law.en
dc.identifier.journalPerceptionen
ref.citationcount0 [Scopus, 19/03/2010]en
or.citation.harvardSoranzo, A., Galmont, A. and Agostini, T. (2009) 'The perceptual contrast of impossible shadow edges', Perception, 38 (2), pp.164–172.-
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