Abstract
When viewing the concentric circles, which consist of oblique components, the observers see an illusory rotation of the circles by changing the viewing distance (Pinna & Brelstaff, 2000, Vision Research, 40, 2091-2096). 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, which have no means for generating illusory motion themselves, is based on "motion capture". In this study, we examined how the amount of superimposed elements affect the illusory rotation for the circles (150mm in diameter) and motion capture for the superimposed elements. The inner and outer rings each consist of 72 oblique black lines on a white background. Each line was tilted radially by 30 degree. The amount of superimposed element, which were arc-shape with intersection angle of 9 degree, ranged from 0 to 40. Observers viewed the stimuli by repeatedly moving the head forward and backward at a rate that felt comfortable. Observers reported the direction of the rotation (clockwise or anticlockwise when approaching the figure), and evaluated the magnitude of the illusory motion for the inner circle and superimposed elements. While the illusory rotation for the circles mostly decreased at the middle range of the amount of superimposed elements, that for the superimposed elements increased monotonically with the increment of elements. These results suggest that the motion capture is not caused by perceptual dragging of the superimposed elements by the motion illusion for the oblique lines. Rather, the motion capture for the superimposed elements is caused by the local leakage of motion signal from the oblique components, and accumulation of the motion signal at each superimposed element.
Meeting abstract presented at VSS 2013