Verstraten F A, Verlinde R, Fredericksen R E, van de Grind W A
Utrecht Biophysics Research Institute, The Netherlands.
Perception. 1994;23(10):1181-8. doi: 10.1068/p231181.
Under transparent motion conditions overlapping surfaces are perceived simultaneously, each with its own direction. The motion aftereffect (MAE) of transparent motion, however, is undirectional and its direction is opposite to that of a sensitivity-weighted vector sum of both inducing vectors. Here we report a bidirectional and transparent MAE contingent on binocular disparity. Depth (from retinal disparity) was introduced between two patterns. A fixation dot was presented at zero disparity, that is, located between the two adaptation patterns. After adaptation to such a stimulus configuration testing was carried out with two stationary test patterns at the same depths as the preceding moving patterns. For opposite directions a clear transparent MAE was perceived. However, if the adaptation directions were orthogonal the chance of a transparent MAE being perceived decreased substantially. This was subject dependent. Some subjects perceived an orthogonal transparent MAE whereas others saw the negative vector sum-an integrated MAE. In addition the behavior of the MAE when the distance in depth between adapting and test patterns was increased was investigated: it was found that the visibility of the MAE then decreased. Visibility is defined in this paper as: (i) the percentage of the trials in which MAEs are perceived and (ii) the average MAE duration. Both measures decreased with increasing distance. The results suggest that segregation and integration may be mediated by direction-tuned channels that interact with disparity-tuned channels.
在透明运动条件下，重叠表面能同时被感知，每个表面都有其自身的方向。然而，透明运动的运动后效（MAE）是无方向的，其方向与两个诱导向量的敏感度加权向量和的方向相反。在此，我们报告一种基于双眼视差的双向透明MAE。在两种图案之间引入了深度（由视网膜视差产生）。在零视差处呈现一个注视点，即位于两个适应图案之间。在适应这种刺激配置后，用与先前运动图案相同深度的两个静止测试图案进行测试。对于相反方向，能清晰地感知到透明MAE。然而，如果适应方向是正交的，感知到透明MAE的可能性会大幅降低。这因个体而异。一些受试者感知到正交透明MAE，而另一些受试者看到的是负向量和——一种整合的MAE。此外，还研究了适应图案和测试图案之间深度距离增加时MAE的表现：发现此时MAE的可见度降低。本文将可见度定义为：（i）感知到MAE的试验百分比，以及（ii）平均MAE持续时间。这两种测量指标都随距离增加而降低。结果表明，分离和整合可能由与视差调谐通道相互作用的方向调谐通道介导。
