Counter-changing luminance: A non-Fourier, nonattentional basis for the perception of single-element apparent motion.

Motion perception was studied for generalized apparent motion stimuli composed of 2 simultaneously visible elements whose luminance alternated between 2 values (only 1 element is visible at a time for standard apparent motion). It was demonstrated that 1st-order motion energy is neither necessary nor sufficient for the perception of apparent motion. Instead, it was found that counter-changing luminance--simultaneous luminance changes at 2 element locations--is the informational basis for perceiving luminance-defined apparent motion: Motion starts where luminance changes toward the background luminance value and ends where luminance changes away from the background luminance. The results were not attributable to either 2nd-order motion mechanisms (for which rectification precedes the computation of motion energy) or attention-based, 3rd-order motion mechanisms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)