Department of Psychology, New York University, New York, NY, USA.
Department of Psychology, New York University Abu Dhabi, Abu Dhabi, UAE.
J Vis. 2023 Mar 1;23(3):19. doi: 10.1167/jov.23.3.19.
The discriminability of motion direction is asymmetric, with some motion directions that are better discriminated than others. For example, discrimination of directions near the cardinal axes (upward/downward/leftward/rightward) tends to be better than oblique directions. Here, we tested discriminability for multiple motion directions at multiple polar angle locations. We found three systematic asymmetries. First, we found a large cardinal advantage in a cartesian reference frame - better discriminability for motion near cardinal reference directions than oblique directions. Second, we found a moderate cardinal advantage in a polar reference frame - better discriminability for motion near radial (inward/outward) and tangential (clockwise/counterclockwise) reference directions than other directions. Third, we found a small advantage for discriminating motion near radial compared to tangential reference directions. The three advantages combine in an approximately linear manner, and together predict variation in motion discrimination as a function of both motion direction and location around the visual field. For example, best performance is found for radial motion on the horizontal and vertical meridians, as these directions encompass all three advantages, whereas poorest performance is found for oblique motion stimuli located on the horizontal and vertical meridians, as these directions encompass all three disadvantages. Our results constrain models of motion perception and suggest that reference frames at multiple stages of the visual processing hierarchy limit performance.
运动方向的可辨别性是不对称的，有些运动方向比其他方向更容易辨别。例如，与斜向方向相比，更接近主坐标轴（向上/向下/向左/向右）的方向的辨别能力往往更好。在这里，我们测试了多个极角位置的多个运动方向的可辨别性。我们发现了三个系统的不对称性。首先，我们在笛卡尔参考系中发现了一个大的主优势——与斜向方向相比，更接近主参考方向的运动具有更好的辨别能力。其次，我们在极坐标参考系中发现了一个中等的主优势——与其他方向相比，更接近径向（向内/向外）和切向（顺时针/逆时针）参考方向的运动具有更好的辨别能力。第三，我们发现径向运动比切向运动更有利于辨别。这三个优势以近似线性的方式结合在一起，共同预测了运动辨别力随运动方向和视野周围位置的变化。例如，在水平和垂直子午线处的径向运动表现最佳，因为这些方向包含了所有三个优势，而在水平和垂直子午线上的斜向运动刺激表现最差，因为这些方向包含了所有三个劣势。我们的结果限制了运动感知模型，并表明视觉处理层次结构多个阶段的参考系限制了性能。
