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Apparent motion by edge discontinuities

Fantoni, Carlo and Pinna, Baingio (2008) Apparent motion by edge discontinuities. Perception, Vol. 37 (7), p. 973-992. eISSN 1468-4233. Article.

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DOI: 10.1068/p5782

Abstract

When the eyes move vertically across a jagged diamond, a local shift (LS) of edge discontinuities and a global shape distortion (GD) (ie expansion/contraction opposite to that expected by the aperture effect) are perceived. These phenomena cannot be accounted for by a local motion signals integration rule based either on the intersection of constraint lines or on the velocity vector summation. The threshold for GD perception and the salience of LS and GD (1 to 10 scale) were measured in two experiments by different methods and displays. In experiment 1 we induced GD through mimicking LS with a kinetic pattern constituted of a set of circular illusory apertures revealing drifting gratings. The point of subjective equality for compression/expansion was reached for gratings the linear extrapolations of which form an angle of 94.4°. In experiment 2 observers followed a dot moving along the vertical elongation axis of a static jagged diamond (with 70° or 90° angles), varying in the shape (triangular, wave, square), frequency, and amplitude of edge discontinuities. GD scores were correlated with LS scores that were inversely related to frequency/amplitude ratios of triangular edge discontinuities. Data are partially accounted for by averaging neighbouring local motion-capture vectors. Results prove that there are strong interrelations between phenomena in which visual motion affects visual localisation and phenomena involving apparent deformation of global shape.

Item Type:Article
ID Code:2949
Status:Published
Refereed:Yes
Uncontrolled Keywords:Edge discontinuity, eye movement, apparent motion
Subjects:Area 11 - Scienze storiche, filosofiche, pedagogiche e psicologiche > M-PSI/01 Psicologia generale
Divisions:001 Università di Sassari > 01 Dipartimenti > Scienze dei linguaggi
Publisher:Pion
eISSN:1468-4233
Deposited On:09 Sep 2009 13:28

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