Barton J J, Rizzo M, Nawrot M, Simpson T
Division of Neurology, University of Toronto, Ontario, Canada.
Vision Res. 1996 Oct;36(19):3051-9. doi: 10.1016/0042-6989(96)00063-6.
We evaluated the effect of +3.25 dioptres of optical blur on the discrimination of motion direction in random dot cinematograms. Dot displacement between frames varied from 2.1 to 63' of visual angle while the temporal interval was held constant. Optical blur worsened discrimination in three normal subjects at displacements below 16', but improved discrimination at displacements of 21' or more. In a second experiment, two subjects viewed equivalent velocity stimuli constructed with different combinations of temporal interval and spatial displacement. Results showed that the effect of blur was specific to displacement and not velocity. Furthermore, varying the dot density of the display showed that the effect of blur correlated with dot displacement and not the probability of dot mismatches. Since optical blur attenuates high spatial frequencies, this suggests that high spatial frequencies are important for motion perception when dot displacements are less than 16' to 21', but reduce motion perception at larger dot displacements. The use of random dot cinematograms in populations must take into account stimulus displacement and optical causes of reduced spatial acuity.
我们评估了 +3.25 屈光度的光学模糊对随机点电影图像中运动方向辨别能力的影响。各帧之间的点位移在视角的 2.1 至 63' 之间变化，而时间间隔保持恒定。在位移低于 16' 时，光学模糊使三名正常受试者的辨别能力变差，但在位移为 21' 或更大时，辨别能力得到改善。在第二个实验中，两名受试者观看了由不同时间间隔和空间位移组合构建的等效速度刺激。结果表明，模糊的影响特定于位移而非速度。此外，改变显示器的点密度表明，模糊的影响与点位移相关，而非点不匹配的概率。由于光学模糊会衰减高空间频率，这表明当点位移小于 16' 至 21' 时，高空间频率对运动感知很重要，但在较大点位移时会降低运动感知。在人群中使用随机点电影图像时，必须考虑刺激位移和空间敏锐度降低的光学原因。
