Loewenstein Rehabilitation Center, Raanana and Sackler Faculty of Medicine, Tel Aviv University.
J Cogn Neurosci. 1997 Nov;9(6):824-34. doi: 10.1162/jocn.1997.9.6.824.
The present research examines the effect of spatial (object-centered) attentional constraints on pattern recognition. Four normal subjects and two right-hemisphere-damaged patients with left visual neglect participated in the study. Small, letterlike, prelearned patterns served as stimuli. Short exposure time prevented overt scanpaths during stimulus presentation. Attention was attracted to a central (midsagittal) hation point by precuing this location prior to each stimulus presentation. Minute (up to 1.5° of visual angle) rightward and leftward stimulus shifts caused attention to be allocated each time to a different location on the object space, while remaining in a fixed central position in viewercentered coordinates. The task was to decide which of several prelearned patterns was presented in each trial. In the normal subjects, best performance was achieved when the luminance centroid (LC; derived from the analysis of low-spatial frequencies in the object space) of each pattern coincided with the spatial position of the precue. In contrast, the patients with neglect showed optimal recognition performance when precuing attracted attention to locations within the object space, to the left of the LC. The normal performance suggests that the LC may serve as a center of gravity for attention allocation during pattern recognition. This point seems to be the target location where focal attention is normally directed, following a primary global analysis based on the low spatial frequencies. Thus, the LC of a simple pattern may serve as the origin point for an object-centered-coordiate-frame (OCCF), dividing it into right and left. This, in turn, serves to create a prototype description of the pattern, in its own coordinates, in memory, to be addressed during subsequent recognition tasks. The best match of the percept with the stored description may explain the observed advantage of allocating attention to the LC. The performance of the brain- damaged patients can be explained in terms of neglect operating in the OCCE.
本研究考察了空间（以物体为中心）注意约束对模式识别的影响。四名正常受试者和两名右脑损伤、左侧视觉忽视的患者参与了研究。小的、字母形状的、预先学习的模式作为刺激。短的呈现时间防止在刺激呈现过程中出现明显的扫视路径。通过在每次刺激呈现前预先提示这个位置，将注意力吸引到中央（正中矢状面）位置。微小的（最多 1.5°的视角）向右和向左的刺激转移每次都会将注意力分配到物体空间的不同位置，而在以观察者为中心的坐标中保持在固定的中央位置。任务是在每次试验中决定呈现了几个预先学习的模式中的哪一个。在正常受试者中，当每个模式的亮度质心（LC；从物体空间的低空间频率分析中得出）与预提示的空间位置相吻合时，表现最佳。相比之下，忽视患者在预提示吸引注意力到 LC 左侧的物体空间位置时表现出最佳的识别性能。正常表现表明，LC 可能作为模式识别过程中注意力分配的重心。这个点似乎是正常情况下焦点注意力指向的目标位置，遵循基于低空间频率的初步全局分析。因此，简单模式的 LC 可能作为以物体为中心的坐标框架（OCCF）的原点，将其分为左右两部分。这反过来又会在记忆中创建模式的原型描述，以其自身的坐标，以便在后续的识别任务中使用。感知与存储描述的最佳匹配可能解释了将注意力分配到 LC 的优势。脑损伤患者的表现可以用 OCCE 中的忽视来解释。
