Abstract：
We compare the recognition of foveal crowded Landolt Cs of two sizes: brief (40 ms), large, low-contrast Cs and high-contrast (1 sec) tests at the resolution limit of the visual system. In different series, the test Landolt C was surrounded by two identical distractors located symmetrically along the horizontal or by a single distractor. The distractors were Landolt Cs or rings. At the resolution limit, the critical spacing was similar in the two series and did not depend on the type of distractor. The result supports the hypothesis that crowding at the resolution limit occurs when both the test and the distractors fall into the same smallest receptive field responsible for the target recognition. For large stimuli, at almost all separations distractors of the same shape caused greater impairment than did rings, and recognition errors were non-random. The critical spacing was equal to 0.5 test diameters only in the presence of one distracting Landolt C. This result suggests that attention is involved: When one distractor is added, involuntary attention, which is directed to the centre of gravity of the stimulus, can lead to confusion of features that are present in both tests and distractors and thus to non-random errors.
摘要：
我们比较了两种尺寸的中央凹拥挤的LandoltCs的识别：简短(40毫秒)，大,低对比度Cs和高对比度（1秒）测试在视觉系统的分辨率极限。在不同的系列中，测试LandoltC被沿水平方向对称放置的两个相同的干扰物或单个干扰物包围。干扰者是LandoltCs或环。在分辨率限制下，临界间距在两个系列中相似，并且不取决于干扰物的类型。结果支持以下假设：当测试和干扰物都落入负责目标识别的同一最小感受域时，会发生分辨率极限下的拥挤。对于大的刺激，在几乎所有的分离中，相同形状的干扰物造成的损害比戒指更大，识别错误是非随机的。仅在存在一个分散注意力的LandoltC的情况下，临界间距等于0.5个测试直径。该结果表明涉及到注意力：当添加一个分散器时，非自愿的注意，指向刺激的重心，会导致测试和干扰因素中存在的特征混淆，从而导致非随机错误。
