Recent work on the visual system of primates has delineated several cortical fields involved in the processing of visual motion. These cortical areas appear to be connected anatomically in stages, which suggests that there is a hierarchy in the machinery for motion perception. In this paper, we outline experiments that we have performed along the most prominent pathway for motion analysis, which begins in area V1 and proceeds through the middle temporal area (MT) to the medial superior temporal area (MST).