Studies on Induced Motion in the Third Dimension

Abstract

Three experiments are described on induced motion in the third dimension. In experiment 1 two constant lines on a sheet of glass appear to move in depth as a consequence of the rapid displacements of a back surface (real inducing motion); this apparent motion is the more evident (i) the longer the inspection time and (ii) the faster the inducing stimulus. In experiment 2 a constant circle appears to move in depth as a consequence of the stroboscopic displacement of a surrounding circle (apparent inducing motion). Experiment 3 compares this last induced-motion effect with the aftereffect. The importance of a dynamic frame of reference is stressed.