Motion streaks do not influence the perceived position of stationary flashed objects.
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.
Cognitive Neuroscience Sector, International School for Advanced Studies-Via Bonomea 265, 34136 Trieste, Italy. apavan@sissa.it
Andrea
A
Pavan
Rosilari
R
Bellacosa Marotti
D000465:Algorithms; D003196:Computer Graphics; D004867:Equipment Design; D006801:Humans; D007088:Illusions; D009038:Motion; D009039:Motion Perception; D016011:Normal Distribution; D010465:Perception; D010775:Photic Stimulation / Q000379:methods*; D015203:Reproducibility of Results; D013028:Space Perception; D014584:User-Computer Interface; D014792:Visual Acuity