PURPOSE:Tilt aftereffect (TAE)[1]is the phenomenon that the perceived orientation of a test stimulus is altered after prolonged exposure to an oriented adaptor.This phenomenon has been widely considered to result from adaptation of orientation-selective neurons in the early visual cortex.In this study,we investigated whether the TAE could be induced from a perceived illusory orientation of adapting stimulus dissociated from its physical orientation,by taking advantage of a new illusion— the flash grab effect[2].