Perceived onset time and position of a moving stimulus

During the few past years, there has been a growing interest in the timing and locating of moving stimuli. The most popular spatio-temporal phenomena that have been studied are the flash-lag effect (FLE) [Nature 370 (1994) 256] and the Fröhlich effect (FE) [Z. Sinnesphysiol. 54 (1923) 58]. Most often these phenomena are examined by some spatial task (e.g., judging whether moving and flashed stimuli are spatially aligned or not; explicitly pointing or adjusting the moving stimulus position). Usually, from the measured spatial offset temporal differences in processing of moving and stationary stimuli are inferred. Our experiments show that this practice may not be justified because the spatial and temporal properties were clearly disassociated for the movement onset perception. The disassociation demonstrates that the FLE and FE are most probably based on different internal representations.