Masahiro SUZUKI^*

Human Media Research Center, Kanagawa Institute of Technology, Atsugi, Kanagawa 243-0292, Japan

(Received September 5, 2013; Revised January 27, 2014; Accepted April 21, 2014)

This study examined the mechanism of alpha motion, the apparent motion of the Müller–Lyer figure's shaft that occurs when the arrowheads and arrow tails are alternately presented. The following facts were found: (a) reduced exposure duration decreased the amount of alpha motion, and this phenomenon was not explainable by the amount of the Müller–Lyer illusion; (b) the motion aftereffect occurred after adaptation to alpha motion; (c) occurrence of alpha motion became difficult when the temporal frequency increased, and this characteristic of alpha motion was similar to the characteristic of a motion detector that motion detection became difficult when the temporal frequency increased from the optimal frequency. These findings indicated that alpha motion occurs on the basis of a motion detector but not on the Müller–Lyer illusion, and that the mechanism of alpha motion is the same as that of general motion perception.

Key words: Müller–Lyer illusion, geometrical-optical illusions, optical illusions, alpha motion, apparent motion, motion perception, motion detectors, motion detection mechanism, temporal characteristics, temporal frequency characteristics

^*E-mail address: msuzuki@ctr.kanagawa-it.ac.jp