Illusory contour strength does not depend on the dynamics or relative phase of the inducers

We use a new objective measure of illusory contour strength, threshold redu ction for aspect ratio discrimination, to examine the effect of dynamics an d relative phase on the Kanizsa illusion. We found no dependence of illusor y contour strength on the relative phase of flickering inducers (in phase, antiphase, or in quadrature phase) either for the standard Kanizsa square, or for modifications that facilitated or interfered with amodal completion. Comparison with a vernier acuity task indicates that the distance between the inducers, rather than the nature of the task, accounts for the insensit ivity to relative phase. (C) 2000 Published by Elsevier Science Ltd.