Watanabe Katsumi
Visual Cognition Group, Institute for Human Science and Biomedical Engineering, National Institute of Advanced Industrial Science and Technology, AIST Tsukuba Central 6, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan.
Perception. 2005;34(6):687-98. doi: 10.1068/p5415.
When subjects localize a flash relative to another stationary stimulus, the flash appears displaced in the direction of nearby motion signals (position capture; Whitney and Cavanagh, 2000 Nature Neuroscience 3 954-959). Our previous study had suggested that the position capture is larger for a flash presented ahead of a moving stimulus than for a flash behind it (Watanabe et al, 2003 Perception 32 545-559). In the present study, I investigated the spatial asymmetry of position capture. Experiment 1 demonstrated that asymmetric position capture occurs primarily in a moving-object-centered coordinate. Experiment 2 showed evidence that the asymmetric position capture operates after individuation of single visual objects. Finally, experiment 3 demonstrated that, when attention was reduced with a dual-task procedure, the asymmetric position capture increased. These results suggest that the spatial asymmetry of position capture occurs without attention but the spatial bias can be reduced by attention. Therefore, the underlying mechanism for the asymmetric spatial bias may be different from attentive tracking (Cavanagh, 1992 Science 257 1563-1565) and mislocalization during smooth pursuit (Brenner et al, 2001 Vision Research 41 2253-2259).
当受试者将一个闪光相对于另一个静止刺激进行定位时，闪光会朝着附近运动信号的方向出现位移（位置捕获；惠特尼和卡瓦纳，2000年《自然神经科学》第3卷954 - 959页）。我们之前的研究表明，对于出现在移动刺激之前的闪光，位置捕获比出现在其之后的闪光更大（渡边等人，2003年《知觉》第32卷545 - 559页）。在本研究中，我调查了位置捕获的空间不对称性。实验1表明，不对称位置捕获主要发生在以移动物体为中心的坐标系中。实验2显示有证据表明，不对称位置捕获在单个视觉对象个体化之后起作用。最后，实验3表明，当通过双任务程序减少注意力时，不对称位置捕获增加。这些结果表明，位置捕获的空间不对称性在没有注意力的情况下发生，但空间偏差可以通过注意力来减少。因此，不对称空间偏差的潜在机制可能与注意力跟踪（卡瓦纳，1992年《科学》第257卷1563 - 1565页）以及平稳跟踪过程中的错误定位（布伦纳等人，2001年《视觉研究》第41卷2253 - 2259页）不同。
