Abstract
When viewing the concentric circles, which consist of oblique components, the observers see illusory rotation of those circles by changing the viewing distance. If several additional elements were superimposed on the concentric circles, they will see the illusory rotation not only for the circles, but also for the superimposed elements (Ichikawa et al, 2006, Perception, 35, 933-946). This illusory rotation of the superimposed elements is caused by “motion capture”. We examined the basis of the motion capture by changing the number of the superimposed elements (dots) when the rotation of the circles was generated by the Pinna illusion, which is generated by automatic size change of the stimulus on the display, or by apparent motion. A CRT display presented the inner and outer circles (14.3 and 17.2 deg in diameter) each that consisted of 72 oblique lines, which were tilted radially by 30 deg. The numbers of the dots ranged from 0 to 40. The viewing distance was fixed at 50 cm. In the Pinna illusion condition, the stimulus changed its size from 17.2 to 6.9 deg. In the apparent rotation condition, the inner and outer circles rotated to opposite direction by 10.0 deg and 6.0 deg, respectively. In the complex motion condition, the inner and outer circles, which consisted of 72 radial lines, rotated to opposite direction by 10.0 deg and 6.0, respectively, and changed its size from 17.2 to 6.9 deg. In the Pinna illusion and complex motion conditions, we observed the motion capture; the dots moved with the same direction as the rotation of the inner circle. However, in the apparent rotation condition, we observed the induced motion; the dots moved with the opposite direction to the rotation of the inner circle. These results suggest that the motion capture depends upon the assignment of complex motion signals.
Meeting abstract presented at VSS 2015