三度空間平面結構對知覺組織圖形之周邊調節效應的影響

Abstract

The percept of the global form of a Glass pattern can be modulated by the presence of a surround Glass pattern (Li &Chen, 2010). This modulation depends on the global structures of both the central target and the surround. Here, we investigated whether such modulation can be influenced by the 3D configuration of the stimuli. The stimuli contained a central target (2.5 deg radius) and an annulus surround (2.1 deg width). Both the target and surround were either concentric, radial or spiral Glass patterns (4% dot density). The depth modulations were achieved by binocular disparity. There were six 3D configurations: The target and surround were (A) on the same frontoparallel plane; (B) on different frontoparallel planes; (C) on the same 45 deg slanted plane; (D) on different slanted planes (+/-45 deg); (E) on the same concave or convex surface; and (F) on different concave or convex surfaces. The coherence thresholds of the central target Glass patterns were measured at 75% accuracy with a 2AFC paradigm with or without the presence of a surround Glass pattern. When they were on the same surface, the concentric surround suppressed the detection of a concentric target, and the spiral surround suppressed the detection of both concentric and radial target when the surface was frontoparallel or slanted, but not concave/convex. Such surround modulation effect was reduced or abolished when the target and the surround were on different surfaces. The surround modulation occurred only when the target and surround were coplanar regardless the depth difference between the target and the surround. Our results show that the surround modulation in Glass patterns depends on plane assignment.