Baker Daniel H, Graf Erich W
School of Psychology, University of Southampton, Highfield, Southampton, SO17 1BJ, UK.
Vision Res. 2010 Jan;50(2):193-201. doi: 10.1016/j.visres.2009.11.011. Epub 2009 Nov 16.
How does nearby motion affect the perceived speed of a target region? When a central drifting Gabor patch is surrounded by translating noise, its speed can be misperceived over a fourfold range. Typically, when a surround moves in the same direction, perceived centre speed is reduced; for opposite-direction surrounds it increases. Measuring this illusion for a variety of surround properties reveals that the motion context effects are a saturating function of surround speed (Experiment I) and contrast (Experiment II). Our analyses indicate that the effects are consistent with a subtractive process, rather than with speed being averaged over area. In Experiment III we exploit known properties of the motion system to ask where these surround effects impact. Using 2D plaid stimuli, we find that surround-induced shifts in perceived speed of one plaid component produce substantial shifts in perceived plaid direction. This indicates that surrounds exert their influence early in processing, before pattern motion direction is computed. These findings relate to ongoing investigations of surround suppression for direction discrimination, and are consistent with single-cell findings of direction-tuned suppressive and facilitatory interactions in primary visual cortex (V1).
附近的运动如何影响目标区域的感知速度？当一个中心漂移的高斯包络片被平移噪声包围时，其速度可能会在四倍的范围内被错误感知。通常，当周围环境向相同方向移动时，感知到的中心速度会降低；对于相反方向的周围环境，速度会增加。针对各种周围环境属性测量这种错觉发现，运动背景效应是周围环境速度（实验I）和对比度（实验II）的饱和函数。我们的分析表明，这些效应与减法过程一致，而不是速度在区域上进行平均。在实验III中，我们利用运动系统的已知属性来询问这些周围环境效应在何处产生影响。使用二维格子刺激，我们发现一个格子成分的感知速度的周围环境诱导变化会导致感知格子方向的显著变化。这表明周围环境在处理过程的早期就施加了影响，即在计算图案运动方向之前。这些发现与正在进行的关于用于方向辨别周围抑制的研究相关，并且与初级视觉皮层（V1）中方向调谐抑制和促进相互作用的单细胞发现一致。
