追踪会影响小视角下感知航向的精度。

Beintema J A, van den Berg A V

Department of Zoology and Neurobiology, Ruhr University Bochum, 44780, Bochum, Germany.

Vision Res. 2001 Aug;41(18):2375-91. doi: 10.1016/s0042-6989(01)00077-3.

We investigated the interaction between extra-retinal rotation signals and retinal motion signals in heading perception during pursuit eye movement. For limited viewing aperture, the variability in perceived heading strongly depends on the pattern of motion directions. Heading towards a point outside the aperture generates nearly parallel aperture flow. This results in lower precision of perceived heading than heading that renders the radial pattern of flow visible. We ask if the precision is limited by the pattern of flow visible on the retina or that on the screen. During fixation, the two patterns are identical. They are decoupled during pursuit, since pursuit changes radial flow within the aperture on the screen into nearly parallel flow on the retina, and vice versa. The extra-retinal signal is known to reduce systematic errors in the direction of pursuit, thus compensating for the rotational flow during pursuit. We now ask if the extra-retinal signal also affects the precision of heading percepts. It might if at the spatial integration stage the rotational flow has been subtracted out already. A compensation beyond the integration stage, however, cannot undo the change in retinal motion directions so that an effect of pursuit on precision cannot be avoided. We measured the variable and systematic errors in perceived heading during fixation and pursuit for a frontal plane approach, while varying duration, dot lifetime and aperture size. We found precision is effected by pursuit as much as predicted from the pattern of retinal flow, while compensation is significantly greater than zero. This means that the interaction between the extra-retinal signal and visual motion signals takes place after spatial integration of local motion signals. Furthermore, compensation increased significantly with longer duration (0.5-3.0 s), but not with larger aperture size (10-50 degrees ). A larger aperture size did increase the eccentricity of perceived heading.

我们研究了在追踪眼球运动过程中，视网膜外旋转信号与视网膜运动信号在航向感知中的相互作用。对于有限的观察孔径，感知航向的变异性很大程度上取决于运动方向模式。朝向孔径外一点的航向会产生几乎平行的孔径流。这导致与能呈现径向流模式的航向相比，感知航向的精度较低。我们探究这种精度是否受视网膜上可见的流模式或屏幕上的流模式限制。在注视期间，这两种模式是相同的。在追踪过程中它们会解耦，因为追踪会将屏幕上孔径内的径向流变为视网膜上几乎平行的流，反之亦然。已知视网膜外信号可减少追踪方向上的系统误差，从而补偿追踪过程中的旋转流。我们现在要问视网膜外信号是否也会影响航向感知的精度。如果在空间整合阶段旋转流已经被减去，那么可能会有影响。然而，在整合阶段之后的补偿无法消除视网膜运动方向的变化，所以追踪对精度的影响无法避免。我们测量了在固定和追踪过程中，对于正面平面接近时，不同持续时间、点寿命和孔径大小时，感知航向的可变误差和系统误差。我们发现精度受追踪的影响程度与从视网膜流模式预测的一样大，而补偿显著大于零。这意味着视网膜外信号与视觉运动信号之间的相互作用发生在局部运动信号的空间整合之后。此外，补偿随着持续时间延长（0.5 - 3.0秒）显著增加，但随孔径增大（10 - 50度）并未增加。更大的孔径确实增加了感知航向的偏心率。