Bulakowski Paul F, Bressler David W, Whitney David
Department of Psychology, University of California, Davis, CA, USA.
J Vis. 2007 Jul 24;7(10):10.1-10. doi: 10.1167/7.10.10.
One of the most important aspects of visual attention is its flexibility; our attentional "window" can be tuned to different spatial scales, allowing us to perceive large-scale global patterns and local features effortlessly. We investigated whether the perception of global and local motion competes for a common attentional resource. Subjects viewed arrays of individual moving Gabors that group to produce a global motion percept when subjects attended globally. When subjects attended locally, on the other hand, they could identify the direction of individual uncrowded Gabors. Subjects were required to devote their attention toward either scale of motion or divide it between global and local scales. We measured direction discrimination as a function of the validity of a precue, which was varied in opposite directions for global and local motion such that when the precue was valid for global motion, it was invalid for local motion and vice versa. There was a trade-off between global and local motion thresholds, such that increasing the validity of precues at one spatial scale simultaneously reduced thresholds at that spatial scale but increased thresholds at the other spatial scale. In a second experiment, we found a similar pattern of results for static-oriented Gabors: Attending to local orientation information impaired the subjects' ability to perceive globally defined orientation and vice versa. Thresholds were higher for orientation compared to motion, however, suggesting that motion discrimination in the first experiment was not driven by orientation information alone but by motion-specific processing. The results of these experiments demonstrate that a shared attentional resource flexibly moves between different spatial scales and allows for the perception of both local and global image features, whether these features are defined by motion or orientation.
视觉注意力最重要的一个方面在于其灵活性；我们的注意力“窗口”可以调整到不同的空间尺度，使我们能够轻松地感知大规模的全局模式和局部特征。我们研究了对全局和局部运动的感知是否会竞争共同的注意力资源。受试者观看单个移动的加博尔条纹阵列，当受试者进行全局注意力时，这些阵列会组合产生全局运动感知。另一方面，当受试者进行局部注意力时，他们能够识别单个未拥挤的加博尔条纹的方向。受试者被要求将注意力集中在运动的任一尺度上，或者在全局和局部尺度之间分配注意力。我们测量了方向辨别能力，它是预提示有效性的函数，对于全局和局部运动，预提示在相反方向上变化，使得当预提示对全局运动有效时，它对局部运动无效，反之亦然。全局和局部运动阈值之间存在权衡，即在一个空间尺度上增加预提示的有效性会同时降低该空间尺度上的阈值，但会增加另一空间尺度上的阈值。在第二个实验中，我们发现对于静态定向的加博尔条纹也有类似的结果模式：关注局部方向信息会损害受试者感知全局定义方向的能力，反之亦然。然而，方向的阈值高于运动的阈值，这表明第一个实验中的运动辨别并非仅由方向信息驱动，而是由特定于运动的处理驱动。这些实验结果表明，一种共享的注意力资源在不同空间尺度之间灵活移动，并允许对局部和全局图像特征进行感知，无论这些特征是由运动还是方向定义的。
