SPATIAL PHASE DIFFERENCES CAN DRIVE APPARENT MOTION

Can shape differences drive apparent motion? Results from previous res earch are equivocal. Much of the confusion may be due to the use of re latively complex stimuli: letters or geometric shapes, comprising many spatial frequencies, phases, orientations, and contrasts. We focus on relatively simple stimuli: Gaussian damped f+nf compound sinewave gra tings. We examine whether relative phase differences, which are critic al for shape perception, can drive apparent motion. We find that some, but not all, phase differences can drive apparent motion. Specificall y, stimuli that are easily discriminable and perceptually dissimilar c an affect the solution of the correspondence problem. In this case, ob servers consistently perceive stimuli in one frame moving to the posit ion of perceptually similar stimuli in the next frame. This general re sult holds over a wide range of spatial frequencies, orientations, and contrasts. Implications for theories of motion processing are discuss ed.