Is the straddle effect in contrast perception limited to second-order spatial vision?
Is the straddle effect in contrast perception limited to second-order spatial vision?
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DOI：
10.1167/18.5.15
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发表时间：
2018-05-01
影响因子：
1.8
通讯作者：
Wolfson, S. Sabina
中科院分区：
文献类型：
--
作者：
Graham, Norma, V;Wolfson, S. Sabina
之前关于对比度感知中的跨骑效应的研究（Foley，2011; Graham & Wolfson，2007; Wolfson & Graham，2007，2009）使用了视觉模式和被称为空间二阶的观察者任务。在适应约1秒的网格的Gabor补丁都在一个对比度，二阶测试模式组成的两个不同的测试对比可以是容易或难以正确地感知。当两个测试对比度都比自适应对比度小一点（或都比自适应对比度大一点）时，观察者表现得非常好。然而，当两个测试对比跨越适配对比时（即，一个测试对比度大于适配对比度，另一个测试对比度小于适配对比度），性能显著下降。为了解释这种性能的下降-跨式效应-我们提出了一个对比比较过程。我们开始怀疑：二阶模式是跨式效应所必需的吗？在这里，我们表明，答案是“不”。我们展示了跨效应使用空间一阶视觉模式和几个不同的观察员任务。我们还看到了使用一阶视觉模式的对比度归一化的效果，类似于我们之前对二阶视觉模式的发现。我们确实发现了一阶任务和二阶任务之间的一个区别：一阶任务的表现略低。性能稍低可能是由于内存负载稍大。对于许多视觉场景，人类对比度处理中的重要量可能不是物理对比度的单调性，而是可能更像当前对比度和最近平均对比度之间的无符号差异。
Previous work on the straddle effect in contrast perception (Foley, 2011; Graham & Wolfson, 2007; Wolfson & Graham, 2007, 2009) has used visual patterns and observer tasks of the type known as spatially second-order. After adaptation of about 1 s to a grid of Gabor patches all at one contrast, a second-order test pattern composed of two different test contrasts can be easy or difficult to perceive correctly. When the two test contrasts are both a bit less (or both a bit greater) than the adapt contrast, observers perform very well. However, when the two test contrasts straddle the adapt contrast (i.e., one of the test contrasts is greater than the adapt contrast and the other is less), performance drops dramatically. To explain this drop in performance-the straddle effect-we have suggested a contrast-comparison process. We began to wonder: Are second-order patterns necessary for the straddle effect? Here we show that the answer is "no". We demonstrate the straddle effect using spatially first-order visual patterns and several different observer tasks. We also see the effect of contrast normalization using first-order visual patterns here, analogous to our prior findings with second-order visual patterns. We did find one difference between first- and second-order tasks: Performance in the first-order tasks was slightly lower. This slightly lower performance may be due to slightly greater memory load. For many visual scenes, the important quantity in human contrast processing may not be monotonic with physical contrast but may be something more like the unsigned difference between current contrast and recent average contrast.