When alternately and repeatedly presented two pictures, we usually perceive back-and-forth motion between the two images, i.e. regressive motion. In some cases, however, we would perceive progressive motion to the alternate repetition. The present research aims to show the convincing examples and to consider the reason why they do not give the regressive impression to the sequences. We begin with distinguishing two cases; sequential motion and progressive motion. The latter is more important because it contains perceptual and/or technical problems relating to the animation research. We give some examples which belong to the latter; the progressive motion related to the representational momentum (Freyd and Finke, 1984) and the progressive motion known as the twostroke apparent motion (Mather, 2006). Based on the discussion concerning these phenomena, we concluded that the role of context and/or experience would be rather limited.
two-stroke apparent motion
Kanizsa's dancing ostrich