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The Scientific World Journal
Volume 2012 (2012), Article ID 909547, 6 pages
Research Article

Motion Streaks Do Not Influence the Perceived Position of Stationary Flashed Objects

1Cognitive Neuroscience Sector, International School for Advanced Studies (SISSA)—Via Bonomea 265, 34136, Trieste, Italy
2Department of General Psychology, University of Padua, Via Venezia 8, 35131 Padua, Italy

Received 28 October 2011; Accepted 5 December 2011

Academic Editors: M. Rosa and H. Super

Copyright © 2012 Andrea Pavan and Rosilari Bellacosa Marotti. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


In the present study, we investigated whether motion streaks, produced by fast moving dots Geisler 1999, distort the positional map of stationary flashed objects producing the well-known motion-induced position shift illusion (MIPS). The illusion relies on motion-processing mechanisms that induce local distortions in the positional map of the stimulus which is derived by shape-processing mechanisms. To measure the MIPS, two horizontally offset Gaussian blobs, placed above and below a central fixation point, were flashed over two fields of dots moving in opposite directions. Subjects judged the position of the top Gaussian blob relative to the bottom one. The results showed that neither fast (motion streaks) nor slow moving dots influenced the perceived spatial position of the stationary flashed objects, suggesting that background motion does not interact with the shape-processing mechanisms involved in MIPS.