Spatial and temporal characteristics of perceptual completion at the blind spot

本研究考察了盲点知觉完成或填充，知觉完成是视觉系统恢复外部世界的重要功能之一，具体地说，盲点知觉完成是物理空间恢复的代表。以往关于盲点知觉完成的研究主要是定性的，而不是定量的(如Ramachandran，1992)。在本研究中，我们使用带间隙的线刺激来定量检验盲点知觉完成。测试线被呈现在盲点上，因此缺口正好落在观察者右眼的盲点上。观察者被要求报告测试线似乎与参考线相同，参考线是连续的，并以与测试线相同的偏心率呈现给颞部视网膜。知觉完成被定义为测试线的空隙看起来像参考线一样被填充，并测量了发生填充的线段的最小长度。6个实验结果表明：(1)当盲区两侧的线段很短时，表现为分别位于不同位置的两个线段。(2)直线垂直方向的最小填充线段长度大于水平方向的最小长度。(3)知觉完成的各向异性不依赖于盲点水平轴和垂直轴的不同。(4)测试线的宽度和曝光时间影响盲点的知觉完成。(5)我们发现的各向异性被另一种刺激模式所证实。(6)盲点的知觉完成容忍线段在错位、定向和对比度方面的差异。

The present study examined perceptual completion, or filling-in, at the blind spot Perceptual completion is one of important functions of the visual system in order to restore the outer world Specifically, perceptual completion at the blind spot is representative of the restoration of physical space. Previous studies on perceptual completion at the blind spot were mainly qualitative, not quantitative (e.g., Ramachandran, 1992).In this study, we examined quantitatively perceptual completion at the blind spot by using a line stimulus with a gap. The test line was presented across the blind spot so that the gap fell exactly on the blind spot of observer's right eye. Observers were required to report that the test line appeared to be identical to the reference line, which was continuous and presented to the temporal retina with the same eccentricity of the test line. Perceptual completion was defined as that the gap of the test line appeared filled in as like as the reference line and the minimum length of the line segment for filling-in to occur was measured. The following results were obtained from the six experiments.(1)When the line segments in the opposite sides of the blind spot were very short, they appeared as the two line segments located separately in different positions.(2)The minimum length of the line segments for filling-in to occur was larger in the vertical orientation of the line than that in the horizontal orientation. Thus, there is anisotropy of perceptual completion at the blind spot.(3)The anisotropy of perceptual completion does not depend on the difference of the horizontal and vertical axis of the blind spot.(4)The width and exposure duration of the test line affected on perceptual completion at the blind spot.(5)The anisotropy we found was confirmed by another stimulus pattern, such as line grating.(6)Perceptual completion at the blind spot tolerated differences in misalignment, orientation, and contrast of the line segments.