Stimulus dependence of the flash-lag effect.

When two moving objects are presented in perfect alignment, but are not visible for the same amount of time, the briefer object will often be perceived as "lagging" the object of greater duration. Most investigations of this flash-lag effect (FLE) employ high velocity broadband stimuli, such as lines or dots with sharp boundaries and flashes with rapid onset and offset. We introduce a stimulus paradigm with narrow-band stimuli and measure the stimulus dependence of the FLE when basic stimulus parameters of spatio-temporal frequency and temporal duration are varied. We suggest that this dependence is consistent with the involvement of early visual mechanisms and interpret our results in the context of existing theories of the FLE.