Edwin Dickinson J, Badcock David R
School of Psychology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
Vision Res. 2009 Mar;49(6):648-56. doi: 10.1016/j.visres.2009.01.009. Epub 2009 Jan 29.
The retinal flow of information during locomotion provides cues to instantaneous heading. Reconciliation of observer trajectory with the internal representation of the environment implies that the positions of the centre of structure of global motion can be localized relative to points in the visual field. Humans are also sensitive to global structure in Glass patterns, which can approximate temporally integrated optic flow. Encoding of the position of centre of structure of Glass patterns could augment the motion information. However, Glass-like pattern structure could also be present in the texture of objects and indicate their centres, raising the question of whether the centres of form and motion patterns are encoded separately. Psychophysical methods are used to examine ability to localize the centres of structure of Glass and global dot motion (GDM) patterns. Radial and concentric Glass patterns are localized more precisely than spiral Glass patterns but performance in localizing the centres of radial, concentric and spiral GDM patterns is equally precise. Also, Glass patterns centres can be localized at signal levels close to their threshold for discrimination from wholly incoherent patterns but GDM pattern centres cannot, suggesting that detectors for looming and rotating stimuli exist that do not rely on the provision of a centre of structure. Collectively, our results provide evidence for independent encoding of the positions of the centres of structure of global motion and form patterns. These positions can be accurately and precisely localized within the visual field. While the centres of structure of a number of form patterns can be simultaneously encoded, allowing their positions to be compared, only a single focus of expansion for optic flow is returned.
运动过程中视网膜的信息流为即时航向提供线索。将观察者轨迹与环境的内部表征相协调意味着，全局运动结构中心的位置可以相对于视野中的点进行定位。人类对格拉斯图案中的全局结构也很敏感，这种图案可以近似于时间整合的光流。格拉斯图案结构中心的编码可以增强运动信息。然而，类似格拉斯图案的结构也可能存在于物体的纹理中并指示其中心，这就提出了形式和运动图案的中心是否被分别编码的问题。采用心理物理学方法来检验定位格拉斯图案和全局点运动（GDM）图案结构中心的能力。径向和同心格拉斯图案的定位比螺旋格拉斯图案更精确，但在定位径向、同心和螺旋GDM图案中心方面的表现同样精确。此外，格拉斯图案中心可以在接近其与完全不连贯图案区分阈值的信号水平上被定位，但GDM图案中心则不能，这表明存在不依赖于提供结构中心的逼近和旋转刺激探测器。总体而言，我们的结果为全局运动和形式图案结构中心位置的独立编码提供了证据。这些位置可以在视野内被准确且精确地定位。虽然一些形式图案的结构中心可以同时被编码，从而能够比较它们的位置，但光流的扩展只有一个焦点。
