Derrington A, Cox M
Department of Optometry, University of Bradford, UK.
Vision Res. 1998 Nov;38(22):3531-9. doi: 10.1016/s0042-6989(98)00050-9.
We addressed the question of whether low-level motion analysers can integrate signals binocularly. We compared the temporal sensitivity in motion discrimination tasks using monocular and dichoptic first-order motion and monocular and dichoptic second-order motion. Three human observers were required to discriminate the direction of motion of either sinusoidal gratings (1 c/deg), used as a stimulus for first-order motion analysers, or the envelopes of contrast-modulated stationary sinusoidal gratings (carrier frequency 5 c/deg, carrier contrast 0.1, modulation frequency 1 c/deg), used as a stimulus for second-order motion analysers. Contrast sensitivity was measured as a function of temporal frequency. The moving grating or envelope was generated by summing two non-moving sinusoidally flickering gratings or envelopes in spatiotemporal quadrature. These were either combined monocularly or presented dichoptically. Sensitivity to the moving envelope was highest at a temporal frequency between 0.5 and 2 Hz, depending on the observer, and declined rapidly at high temporal frequencies. None of the observers was able to discriminate the direction of motion of envelopes moving faster than 4 Hz. Dichoptic and monocular presentation produced very similar results. Sensitivity to a monocularly presented moving grating was fairly uniform between 1 and 8 Hz, and declined slightly at 16 Hz. In one of three observers sensitivity to the dichoptically presented grating was very close to that of the monocularly presented grating at all temporal frequencies tested (from 1 to 16 Hz). All observers could discriminate the direction of motion of the dichoptically presented grating at 8 Hz, but two of the three were unable to discriminate its direction of motion at 16 Hz. These results indicate that second-order motion analysers have very poor temporal resolution and that dichoptic motion analysers have very good resolution. We suggest that this implies that there are low-level motion analysers that are capable of integrating information binocularly.
我们探讨了低水平运动分析器能否进行双眼信号整合的问题。我们比较了在运动辨别任务中使用单眼和双眼一阶运动以及单眼和双眼二阶运动时的时间敏感性。三名人类观察者需要辨别正弦光栅（1周/度）的运动方向，正弦光栅用作一阶运动分析器的刺激物，或者辨别对比度调制的静止正弦光栅（载波频率5周/度，载波对比度0.1，调制频率1周/度）的包络线方向，该静止正弦光栅用作二阶运动分析器的刺激物。对比度敏感性作为时间频率的函数进行测量。移动光栅或包络线是通过将两个非移动的正弦闪烁光栅或包络线在时空正交中相加而生成的。这些光栅或包络线要么单眼组合，要么双眼呈现。对移动包络线的敏感性在0.5至2赫兹之间的时间频率处最高，具体取决于观察者，并且在高时间频率处迅速下降。没有观察者能够辨别移动速度超过4赫兹的包络线的运动方向。双眼和单眼呈现产生了非常相似的结果。对单眼呈现的移动光栅的敏感性在1至8赫兹之间相当均匀，在16赫兹时略有下降。在三名观察者中的一名中，在所有测试的时间频率（从1至16赫兹）下，对双眼呈现光栅的敏感性与对单眼呈现光栅的敏感性非常接近。所有观察者都能辨别在8赫兹时双眼呈现光栅的运动方向，但三名观察者中有两名无法辨别其在16赫兹时的运动方向。这些结果表明，二阶运动分析器的时间分辨率非常差，而双眼运动分析器具有非常好的分辨率。我们认为，这意味着存在能够双眼整合信息的低水平运动分析器。
