Motion direction discrimination becomes impaired when combinations of drifting high spatial frequency (HSF) and static low spatial frequency (LSF) patterns are merged into a compound stimulus. Such impairment has been suggested to occur due to an interaction between motion sensors tuned to coarse and fine scale spatial patterns. This interaction is modulated by different stimulus parameters like temporal frequency, size, the spectral components mixed, and their relative contrast. The present research precisely aims to explore in a deeper way the interaction's dependency upon the spatial frequency and the relative contrast of the components when both move coherently. Two experiments were therefore performed measuring duration thresholds (Experiment 1) and proportion of correct responses (Experiment 2) in a motion direction discrimination task. Stimuli were vertical Gabor patches of 4 deg diameter horizontally drifting with a speed of 2 deg/sec. Simple LSF and HSF stimuli as well as complex stimuli where both components moved coherently (LSFm + HSFm) were used. These were grouped in the following LSF and HSF pairs: 0.25-0.75, 0.5-1.5, 1-3 and 2-6 c/deg. Each component had a Michelson contrast of 28% or 7%, giving rise to different relative contrast combinations. Most interestingly, the results show a decrease in performance for complex stimuli with respect to each of their simple components when the LSF component has a lower contrast than the HSF one. The decrease depends on the particular spatial frequencies mixed in a stimulus. Further knowledge about the inhibitory mechanism is thus provided, revealing its joint dependency upon contrast and spatial frequency.

中文翻译：

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运动标度之间的相互作用：当复合刺激的运动判别性能比其积分成分差时。

当漂移高空间频率（HSF）模式和静态低空间频率（LSF）模式的组合合并为复合刺激时，运动方向判别会受到损害。已经提出，由于被调整为粗略和精细尺度的空间模式的运动传感器之间的相互作用而发生这种损伤。这种交互作用是通过不同的刺激参数进行调制的，例如时间频率，大小，混合的光谱成分及其相对对比度。本研究的目的在于以更深层次的方式探索相互作用在空间上的依赖关系以及当组分相干运动时组分之间的相对对比度。因此，进行了两个实验，测量了运动方向判别任务中的持续时间阈值（实验1）和正确响应的比例（实验2）。刺激是直径为4度的垂直Gabor斑块，以2度/秒的速度水平漂移。使用简单的LSF和HSF刺激以及复杂的刺激，其中两个成分相干移动（LSFm + HSFm）。将它们分为以下LSF和HSF对：0.25-0.75、0.5-1.5、1-3和2-6 c / deg。每个分量的迈克尔逊对比度为28％或7％，从而产生了不同的相对对比度组合。最有趣的是，结果显示，当LSF分量的对比度低于HSF分量时，相对于其每个简单分量，复杂刺激的性能都会下降。减少取决于刺激中混合的特定空间频率。因此，提供了有关抑制机制的更多知识，揭示了其对对比度和空间频率的共同依赖性。