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Visual summation of luminance lines and illusory contours induced by pictorial, motion, and disparity cues
Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
2001 (English)In: Vision Research, ISSN 0042-6989, E-ISSN 1878-5646, Vol. 41, no 28, 3805-3816 p.Article in journal (Refereed) Published
Abstract [en]

Illusory contours where no contrast exists in the image can be seen between pairs of spatially separate but aligned inducing real contours defined either by pictorial cues (luminance contrasts or offset gratings), kinetic contrast, or binocular disparity contrast. In previous studies it has been shown that the detection of a thin luminous line is facilitated when the line is superimposed on illusory contours and the inducing flanking elements are defined by luminance contrast. By using a spatial forced-choice technique I show that luminous lines summate with illusory contours induced by luminance contrast, offset gratings, motion contrast, and disparity contrast when the line is superimposed on the illusory contour. Control experiments show that the positional cues, offered by the inducing contours, are unable to account for these results. It is suggested that real luminous lines or edges and illusory contours activate common neural mechanisms in the brain irrespectively of the stimulus attributes that induce the illusory contour.

Place, publisher, year, edition, pages
2001. Vol. 41, no 28, 3805-3816 p.
National Category
Social Sciences
Identifiers
URN: urn:nbn:se:uu:diva-90144DOI: 10.1016/S0042-6989(01)00248-6PubMedID: 11738448OAI: oai:DiVA.org:uu-90144DiVA: diva2:162380
Available from: 2003-02-20 Created: 2003-02-20 Last updated: 2017-12-14Bibliographically approved
In thesis
1. Binding Three Kinds of Vision
Open this publication in new window or tab >>Binding Three Kinds of Vision
2003 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Pictorial cues, together with motion and stereoscopic depth fields, can be used for perception and constitute ‘three kinds’ of vision. Edges in images are important features and can be created in either of these attributes. Are local edge and global shape detection processes attribute-specific? Three visual phenomena, believed to be due to low-level visual processes, were used as probes to address these issues. (1) Tilt illusions (misperceived orientation of a bar caused by an inducing grating) were used to investigate possible binding of edges across attributes. Double dissociation of tilt repulsion illusions (obtained with small orientation differences between inducer and bar) and attraction illusions (obtained with large orientation differences) suggest different mechanisms for their origins. Repulsion effects are believed to be due to processes in striate cortex and attraction because of higher level processing. The double dissociation was reproduced irrespective of the attributes used to create the inducing grating and the test-bar, suggesting that the detection and binding of edges across attributes take place in striate cortex. (2) Luminance-based illusory contour perception is another phenomenon believed to be mediated by processes in early visual cortical areas. Illusory contours can be cued by other attributes as well. Detection facilitation of a near-threshold luminous line occurred when it was superimposed on illusory contours irrespective of the attributes used as inducers. The result suggests attribute-independent activation of edge detectors, responding to real as well as illusory contours. (3) The performance in detecting snake-like shapes composed of aligned oriented elements embedded in randomly oriented noise elements was similar irrespective of the attributes used to create the elements. Performance when the attributes alternated along the path was superior to that predicted with an independent channel model. These results are discussed in terms of binding across attributes by feed-forward activation of orientation selective attribute-invariant cells (conjunction cells) in early stages of processing and contextual modulation and binding across visual space mediated by lateral and/or feedback signals from higher areas (dynamic binding).

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2003. 60 p.
Series
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Social Sciences, ISSN 0282-7492 ; 121
Keyword
Psychology, Attribute-invariance, binding, contours, edge linking, gestalt-laws, illusory contour, lateral interactions, neuronal mechanisms, tilt effect, vision, Psykologi
National Category
Psychology
Research subject
Psychology
Identifiers
urn:nbn:se:uu:diva-3319 (URN)91-554-5518-2 (ISBN)
Public defence
2003-03-18, 1022, Jacobsson Widdingsalen, Uppsala, 13:15
Opponent
Available from: 2003-02-20 Created: 2003-02-20Bibliographically approved

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