Geometrical features underlying the perception of collinearity. (November 2016)

• Record Type: Journal Article
• Authors: Morgan, Michael; Dillenburger, Barbara
• Is Part Of: Vision research. Volume 128(2016)
• Page Start: 83
• Page End: 94
• Publication Date: 2016-11
• Subjects: Spatial vision -- Alignment acuity -- Poggendorff; Vision -- Periodicals; 573.88
• DOI: 10.1016/j.visres.2016.09.008
• Languages: English
• ISSNs: 0042-6989

Abstract

Abstract: The magnitude of the Poggendorff bias in perceived collinearity was measured with a 2AFC task and roving pedestal, and was found to be in the region of 6–8 deg, within the range of previous estimates. Further measurements dissected the bias into several components: (1) The small (∼1 deg) repulsion of the orientation of the pointer from the parallel, probably localized in the part of the line near the intersection (2) A small (<1 deg) location bias affecting the intersection of pointers and inducing lines; and (3) A larger (>1 deg) bias in the orientation of virtual lines crossing the gap between two parallels, towards the orientation of the parallels, or equivalently (4) An orthogonal bias in actively constructing a virtual line across the gap. We conclude that orientation repulsion by itself is an inadequate explanation of the Poggendorff effect, and that a full explanation must take account of the way in which observers construct virtual lines in visual space in order to carry out elementary geometrical tasks such as extrapolation.