Cropper S J, Hammett S T
School of Psychology, University of Wales, Cardiff, Wales.
Vision Res. 1997 Aug;37(16):2247-59. doi: 10.1016/s0042-6989(97)00028-x.
It has become apparent from recent work that the spatial frequency and orientation content of the first-order (luminance) carrier is very important in determining the properties of a second-order (contrast) modulation of that carrier. In light of this we examined whether there was any evidence for a motion aftereffect in one-dimensional second-order patterns containing only two sinusoidal luminance components: a spatial beat. The stimuli were either 1 cpd luminance sinusoids or 1 cpd luminance beats modulating a carrier sinusoid of 5 cpd. The magnitude of any motion aftereffect, or any directionally specific effect of adaptation, was measured for all combinations of first and second-order test and adapting patterns. Both flickering and non-flickering stimuli were used. The results indicate that a motion aftereffect is only induced by first-order adapting stimuli, and likewise, is only measurable in first-order test stimuli. We find no evidence for any directionally specific effect of adaptation in second-order stimuli, whether the test is counterphased or otherwise. These results apparently conflict with recent reports of a second-order induced motion aftereffect, but are consistent with many other findings which show differences between the detection of motion for first and second-order stimuli. We conclude that the induction of a motion aftereffect for second-order stimuli is not a general result and is critically dependent upon (amongst other things) the local properties of the stimulus, including the spatial frequency and orientation content of the first-order carrier.
近期的研究工作已表明，一阶（亮度）载波的空间频率和方向内容在决定该载波的二阶（对比度）调制特性方面非常重要。鉴于此，我们研究了在仅包含两个正弦亮度分量的一维二阶图案（空间拍频）中是否存在运动后效的证据。刺激物要么是1周/度的亮度正弦波，要么是调制5周/度载波正弦波的1周/度亮度拍频。针对一阶和二阶测试及适应图案的所有组合，测量了任何运动后效的大小或适应的任何方向特异性效应。使用了闪烁和非闪烁刺激。结果表明，运动后效仅由一阶适应刺激诱发，同样，也仅在一阶测试刺激中可测量。我们没有发现二阶刺激中适应的任何方向特异性效应的证据，无论测试是反相的还是其他情况。这些结果显然与最近关于二阶诱发运动后效的报道相冲突，但与许多其他表明一阶和二阶刺激运动检测存在差异的研究结果一致。我们得出结论，二阶刺激诱发运动后效并非普遍现象，并且（除其他因素外）严重依赖于刺激物的局部特性，包括一阶载波的空间频率和方向内容。
