Is there an auditory-visual 'flash-lag' effect?
A flash adjacent to the path of a moving object appears behind the moving object: the 'flash-lag effect'. We sought to test the flash-lag effect with a 'click' instead of a flash: a white triangle horizontally traversed the screen at a constant 12௳ passing through a fixation cross in the presence of a quiet click. The subject judged whether the click occurred before or after the triangle passed through the cross. To be perceived as co-instantaneous events, the click had to be presented 127 ms after the moving triangle reached the cross (a 'click-lead' effect, providing falsification of predictive accounts of the flash-lag effect), as opposed to a standard flash-lag effect condition where a flashed triangle replaced the click and had to appear 60 ms before the moving triangle to appear aligned. With the auditory versus visual processing speed advantage considered, the neural time required to calculate a moving object's position is constant, independent of the modality of the flag.
Clinical and Experimental Ophthalmology
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