Dillenburger Barbara, Morgan Michael
Max-Planck Institute for Metabolism Research, Cologne, Germany.
Division of Optometry and Visual Science, Institute of Health Sciences, City University London, London, UK.
Iperception. 2017 Apr 21;8(2):2041669517699221. doi: 10.1177/2041669517699221. eCollection 2017 Mar-Apr.
Human participants made saccadic eye movements to various features in a modified vertical Poggendorff figure, to measure errors in the location of key geometrical features. In one task, subjects ( = 8) made saccades to the vertex of the oblique T-intersection between a diagonal pointer and a vertical line. Results showed both a small tendency to shift the saccade toward the interior of the angle, and a larger bias in the direction of a shorter saccade path to the landing line. In a different kind of task (visual extrapolation), the same subjects fixated the tip of a 45° pointer and made a saccade to the implicit point of intersection between pointer and a distant vertical line. Results showed large errors in the saccade landing positions and the saccade polar angle, in the direction predicted from the perceptual Poggendorff bias. Further experiments manipulated the position of the fixation point relative to the implicit target, such that the Poggendorff bias would be in the opposite direction from a bias toward taking the shortest path to the landing line. The bias was still significant. We conclude that the Poggendorff bias in eye movements is in part due to the mislocation of visible target features but also to biases in planning a saccade to a virtual target across a gap. The latter kind of error comprises both a tendency to take the shortest path to the landing line, and a perceptual error that overestimates the vector component orthogonal to the gap.
人类参与者对经过修改的垂直波根多夫图形中的各种特征进行眼跳运动，以测量关键几何特征位置的误差。在一项任务中，8名受试者对对角指针与垂直线之间的倾斜T形交叉点的顶点进行眼跳。结果显示，眼跳有向角内侧偏移的小趋势，以及向着陆线的较短眼跳路径方向的较大偏差。在另一种任务（视觉外推）中，相同的受试者注视45°指针的尖端，并向指针与远处垂直线的隐式交点进行眼跳。结果显示，眼跳着陆位置和眼跳极角存在较大误差，误差方向符合感知波根多夫偏差的预测。进一步的实验操纵了注视点相对于隐式目标的位置，以使波根多夫偏差与向着陆线取最短路径的偏差方向相反。偏差仍然显著。我们得出结论，眼跳中的波根多夫偏差部分是由于可见目标特征的位置错误，也是由于计划跨越间隙向虚拟目标进行眼跳时的偏差。后一种误差既包括向着陆线取最短路径的趋势，也包括高估与间隙正交的矢量分量的感知误差。
