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 grouping of superimposed elements affect the illusory rotation for the circles (136mm in diameter) and motion capture for the superimposed elements that were located at the inner area of the concentric circles. The inner and outer rings each consist of black or white 72 oblique lines on a gray background. Each line was tilted radially by 30 degree. The sum of black and white dots was 40. Within those 40 dots, the amount of black dots was 0, 4, 10, 20, 30, 36, or 40. Observers viewed the stimuli by repeatedly moving the head forward and backward at a rate that felt comfortable. They reported the direction of the rotation, and evaluated the magnitude of the illusory motion for the inner and outer circles, as well as the superimposed dots. The illusory rotation for the inner circle and motion capture most reduced when the amount of black dots was 20, and grouping of dots was difficult because no proximal dots organize a group in terms of similarity in luminance. These results suggest that the motion capture for the superimposed elements is caused by the leakage of motion signal from the oblique components, and accumulation of that motion signal within each group of superimposed elements.
Meeting abstract presented at VSS 2014