Bours Roger J E, Kroes Marijn C W, Lankheet Martin J M
Functional Neurobiology & Helmholtz Institute, Utrecht University, Utrecht, The Netherlands.
J Vis. 2007 Aug 24;7(11):8.1-10. doi: 10.1167/7.11.8.
Periodically flipping the contrast of a moving pattern causes a reversal of the perceived direction of motion. This direction reversal, known as reverse-phi motion, has been generally explained with the notion that flipping contrasts actually shifted the balance of motion energy toward the opposite direction. In this sense, the reversal is trivial because any suitable motion energy detector would be optimally excited in a direction opposite to that for regular motion. This notion, however, does not address the question how these two types of motion are initially detected. Here we show several perceptual phenomena indicating that low-level detection of the two types of motion is quite different. Reverse-phi motion percepts in many respects behave more like motion aftereffects than like regular motion. Motion adaptation causes reduced activity during a stationary test stimulus, which by means of directional opponency leads to motion perceived in the opposite direction. Our findings suggest that reverse-phi motion similarly reduces the activity of low-level motion detectors.
周期性地翻转运动图案的对比度会导致所感知的运动方向发生反转。这种方向反转，即所谓的反向-phi运动，通常被解释为翻转对比度实际上将运动能量的平衡转移到了相反方向。从这个意义上说，这种反转并不重要，因为任何合适的运动能量探测器都会在与常规运动相反的方向上被最佳激发。然而，这个概念并没有解决这两种运动最初是如何被检测到的问题。在这里，我们展示了几种感知现象，表明这两种运动的低水平检测有很大不同。反向-phi运动在许多方面的表现更像运动后效，而不是常规运动。运动适应会导致在静止测试刺激期间活动减少，通过方向对立，这会导致在相反方向上感知到运动。我们的研究结果表明，反向-phi运动同样会降低低水平运动探测器的活动。
