Global contour saliency and local colinear interactions
Global contour saliency and local colinear interactions
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DOI：
10.1152/jn.00289.2002
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发表时间：
2002-11-01
影响因子：
2.5
通讯作者：
Gilbert, CD
中科院分区：
文献类型：
--
作者：
Li, W;Gilbert, CD
我们的视觉系统可以根据几何分组规则连接轮廓的组成部分并将轮廓与复杂背景分离。这是物体识别中重要的中间步骤。轮廓整合的基础可能是基于初级视觉皮层（V1）中的上下文交互和内在水平连接。我们研究了感知规则的轮廓显着性，以确定是否上下文的相互作用和水平连接的空间范围匹配那些中介显着性。为了量化这些规则，我们使用随机取向的非重叠线段组成的刺激。在这个复杂的背景下，显着的轮廓形成的共线对齐附近的片段。轮廓可检测性采用2-区间-强制选择设计进行测量。轮廓检测能力恶化的轮廓元素之间的间距增加和改善的共线线元素的数量增加。在短的轮廓间距，可检测性达到一个平台与几个线段，共同形成一个轮廓对着几个视觉程度的对齐。在中间间距，显着性逐渐建立了更多的共线，延伸到30度。然而，当轮廓间距超过一个临界范围（约20度）时，检测能力下降到机会水平，而不管共线线的数量。轮廓检测能力被发现是一个函数，不仅相对于噪声元素的轮廓元素的相对间距，但也是整体图案的平均密度。此外，训练显著改善了轮廓检测，增加了线元素的临界间距，超过该间距，轮廓不再被检测到。我们的数据表明，全球轮廓整合是基于有限的空间范围内的机制，在V1中观察到的相互作用。这些相互作用可以级联在更大的距离提供刺激元素的间距保持在有限的范围内。
Our visual system can link components of contours and segregate contours from complex backgrounds based on geometric grouping rules. This is an important intermediate step in object recognition. The substrate for contour integration may be based on contextual interactions and intrinsic horizontal connections seen in primary visual cortex (V1). We examined the perceptual rules governing contour saliency to determine whether the spatial extents of contextual interactions and horizontal connections match those mediating saliency. To quantify these rules, we used stimuli composed of randomly oriented nonoverlapping line segments. Salient contours within this complex background were formed by colinear alignment of nearby segments. Contour detectability was measured using a 2-interval-forced-choice design. Contour detectability deteriorated with increasing spacing between contour elements and improved as the number of colinear line elements was increased. At short contour spacing, the detectability reached a plateau with alignment of a few line segments that together formed a contour subtending several visual degrees. At intermediate spacing, saliency built up progressively with a greater number of colinear lines, extending up to 30degrees. When contour spacing was beyond a critical range (about 2degrees), however, the detectability dropped to chance levels, regardless of the number of colinear lines. Contour detectability was found to be a function not only of the relative spacing of contour elements with respect to the noise elements but also of the average density of the overall pattern. Furthermore, training significantly improved contour detection, increasing the critical spacing of line elements beyond which contours were no longer detectable. Our data suggest that global contour integration is based on mechanisms of limited spatial extent, comparable to the interactions observed in V1. These interactions can cascade over larger distances provided the spacing of stimulus elements is kept within a limited range.