Changing the speed, size and material properties of optic flow can significantly alter the experience of vection (i.e. visually induced illusions of self-motion). Until now, there has not been a systematic investigation of the effects of luminance contrast, averaged luminance and stimulus spatial frequency on vection. This study examined the vection induced by horizontally oriented gratings that continuously drifted downwards at either 20° or 60°/s. Each of the visual motion stimuli tested had one of: (a) six different levels of luminance contrast; (b) four different levels of averaged luminance; and (c) four different spatial frequencies. Our experiments showed that vection could be significantly altered by manipulating each of these visual properties. Vection strength increased with the grating’s luminance contrast (in Experiment 1), its averaged luminance (in Experiment 2), and its spatial frequency (in Experiment 3). Importantly, interactions between these three factors were also found for the vection induced in Experiment 4. While simulations showed that these vection results could have been caused by effects on stimulus motion energy, differences in perceived grating visibility, brightness or speed may have also contributed to our findings.

改变光流的速度、大小和材料特性可以显着改变对流的体验（即视觉诱发的自运动错觉）。到目前为止，还没有对亮度对比度、平均亮度和刺激空间频率对矢量的影响进行系统研究。这项研究检查了由水平取向的光栅引起的矢量，这些光栅以 20° 或 60°/s 的速度连续向下漂移。测试的每个视觉运动刺激都具有以下之一：(a) 六个不同级别的亮度对比度；(b) 四种不同级别的平均亮度；(c) 四种不同的空间频率。我们的实验表明，通过操纵这些视觉属性中的每一个，可以显着改变矢量。矢量强度随着光栅亮度对比度的增加而增加（在实验 1 中），它的平均亮度（在实验 2 中）和它的空间频率（在实验 3 中）。重要的是，实验 4 中诱导的矢量也发现了这三个因素之间的相互作用。虽然模拟表明这些矢量结果可能是由对刺激运动能量的影响引起的，但感知光栅可见性、亮度或速度的差异也可能导致我们的发现。