Spatiotemporal characteristics of thresholds adjacent to a luminance edge.
Spatiotemporal characteristics of thresholds adjacent to a luminance edge.
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邻近亮度边缘的阈值的时空特征。
DOI：
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发表时间：
1981
影响因子：
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通讯作者：
U. Tulunay
中科院分区：
文献类型：
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作者：
J. Limb;U. Tulunay
测量了与短暂呈现的垂直边缘相邻的细垂直线（目标）的时空增量和递减阈值。这里使用的刺激物与以前研究中使用的刺激物之间的一个显著差异是呈现边缘的背景水平。在这里，边缘是通过短暂地降低浅色背景左侧的亮度而形成的。这种新条件与更常见的条件进行了比较，在这种情况下，边缘是通过短暂地增加黑暗背景右半部分的亮度形成的。在进一步的测试中，还测量了打开边缘后阈值的积累。当目标呈现在亮度保持固定的边缘一侧时，在边缘附近测量一个小但可靠的阈值变化。在亮度变化的边缘一侧进行测量时，这种影响要大得多；然而，两种情况下的差异是相当的。对于呈现在边缘轻侧的目标，递减阈值远大于递增阈值。这至少部分归因于观察者需要完成不同类型的任务。最大时间阈值提升发生在边缘和目标之间的0异步时或之前（即小于16毫秒）。结果在定性层面上被解释为支持一种接受野类型的模型，在这种模型中，相对于目标的不同时空位置的边缘会抑制或激发以目标为中心的接受野的活动。
Spatiotemporal incremental and decremental thresholds were measured for a thin vertical line (target) positioned adjacent to a briefly presented vertical edge. A significant difference between the stimuli used here and those used in previous studies is the background level against which the edge was presented. Here the edge was formed by briefly decreasing the luminance of the left side of a light background. This novel condition was compared with the more usual condition in which the edge is formed by briefly increasing the luminance of the right half of a dark background. In a further test the buildup of threshold after an edge was switched on was also measured. When the target was presented on the side of the edge that remained fixed in luminance, a small but reliable threshold change adjacent to the edge was measured. The effect was much larger for measurements made on the side of the edge that changed in luminance; however, the spread was comparable for the two conditions. For the target presented on the light side of the edge, decremental thresholds were much larger than incremental thresholds. This is attributed, at least in part, to the different types of tasks required of the observer. Maximum temporal threshold elevation occurs at or just before (i.e., less than 16 msec) 0 asynchrony between edge and target. The results are interpreted at a qualitative level as supporting a receptive-field type of model in which the edge, at various spatiotemporal locations relative to the target, inhibits or excites activity at the receptive field centered on the target.