Key Laboratory for Neuroinformatics, Ministry of Education of China, University of Electronic Sciences and Technology, Chengdu, China.
PLoS One. 2011 Jan 21;6(1):e16343. doi: 10.1371/journal.pone.0016343.
Instantaneous object discrimination and categorization are fundamental cognitive capacities performed with the guidance of visual attention. Visual attention enables selection of a salient object within a limited area of the visual field; we referred to as "field of attention" (FA). Though there is some evidence concerning the spatial extent of object recognition, the following questions still remain unknown: (a) how large is the FA for rapid object categorization, (b) how accuracy of attention is distributed over the FA, and (c) how fast complex objects can be categorized when presented against backgrounds formed by natural scenes.
METHODOLOGY/PRINCIPAL FINDINGS: To answer these questions, we used a visual perceptual task in which subjects were asked to focus their attention on a point while being required to categorize briefly flashed (20 ms) photographs of natural scenes by indicating whether or not these contained an animal. By measuring the accuracy of categorization at different eccentricities from the fixation point, we were able to determine the spatial extent and the distribution of accuracy over the FA, as well as the speed of categorizing objects using stimulus onset asynchrony (SOA). Our results revealed that subjects are able to rapidly categorize complex natural images within about 0.1 s without eye movement, and showed that the FA for instantaneous image categorization covers a visual field extending 20° × 24°, and accuracy was highest (>90%) at the center of FA and declined with increasing eccentricity.
CONCLUSIONS/SIGNIFICANCE: In conclusion, human beings are able to categorize complex natural images at a glance over a large extent of the visual field without eye movement.
瞬间目标识别和分类是在视觉注意力引导下进行的基本认知能力。视觉注意力能够在有限的视野区域内选择一个显著的目标；我们称之为“注意域”（FA）。虽然有一些关于目标识别的空间范围的证据，但以下问题仍不清楚：（a）快速目标分类的 FA 有多大，（b）注意力的准确性如何在 FA 上分布，以及（c）当呈现由自然场景形成的背景时，复杂目标可以多快被分类。
方法/主要发现：为了回答这些问题，我们使用了一种视觉感知任务，要求被试在被要求将注意力集中在一个点上的同时，通过指示这些照片是否包含动物来快速分类短暂闪现（20 毫秒）的自然场景照片。通过测量从注视点到不同偏心率的分类准确性，我们能够确定 FA 的空间范围和准确性分布，以及使用刺激起始异步（SOA）对物体进行分类的速度。我们的结果表明，被试能够在不进行眼动的情况下，在大约 0.1 秒内快速分类复杂的自然图像，并且表明瞬间图像分类的 FA 覆盖了 20°×24°的视野，并且在 FA 的中心处准确性最高（>90%），随着离心率的增加而下降。
结论/意义：总之，人类能够在不进行眼动的情况下，在很大的视野范围内快速地对复杂的自然图像进行分类。
