Mechanism independence for texture-modulation detection is consistent with a filter-rectify-filter mechanism
Mechanism independence for texture-modulation detection is consistent with a filter-rectify-filter mechanism
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DOI：
10.1017/s0952523803201073
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发表时间：
2003-01-01
影响因子：
1.9
通讯作者：
Hayes, A
中科院分区：
文献类型：
--
作者：
Kingdom, FAA;Prins, N;Hayes, A
视觉系统检测亮度或颜色以外的沿着维度变化的刺激--“二阶”刺激--的能力近年来引起了相当大的兴趣。一个重要的未解决的问题是，不同类型的二阶刺激是否被检测到的一个单一的，所有的目的，机制，或由特定的刺激类型的机制。使用传统的心理物理学范式，我们表明，对于一类二阶刺激纹理正弦调制的方向（OM），空间频率（FM），和对比度（CM）-人类视觉系统采用的机制是选择性的刺激类型。而增加一个阈下掩模的测试模式相同的刺激类型，以促进检测的测试，没有便利化时，观察到掩模和测试是不同的类型，这表明机制的独立性，为不同类型的刺激。这一发现提出了一个重要的问题，即机制独立性是否与众所周知的滤波器-整流器-滤波器（FRF）模型的二阶刺激检测兼容，因为FRF机制，在原则上，不区分刺激类型。我们表明，所有的面具/测试的组合，除了那些与CM面具，频响机制给出最大的响应测试调制在很大程度上不受阈下水平的不同刺激类型的面具。因此，我们不能排除FRF机制介导我们对刺激的检测的可能性。然而，对于涉及CM掩模的组合，我们建议对比度归一化的过程使得测试刺激对掩模刺激不敏感。
The ability of the visual system to detect stimuli that vary along dimensions other than luminance or color - "second-order" stimuli-has been of considerable interest in recent years. An important unresolved issue is whether different types of second-order stimuli are detected by a single, all purpose, mechanism, or by mechanisms that are specific to stimulus type. Using a conventional psychophysical paradigm, we show that for a class of second-order stimuli-textures sinusoidally modulated in orientation (OM), spatial frequency (FM), and contrast (CM)-the human visual system employs mechanisms that are selective to stimulus type. Whereas the addition of a subthreshold mask to a test pattern of the same stimulus type was found to facilitate the detection of the test, no facilitation was observed when mask and test were of different types, suggesting mechanism independence for the different types of stimulus. This finding raises the important question of whether mechanism independence is compatible with the well-known filter-rectify-filter (FRF) model of second-order stimulus detection, since FRF mechanisms, in principle, do not discriminate between stimulus types. We show that for all mask/test combinations except those with CM masks, the FRF mechanism giving the largest response to the test modulation is largely unaffected by subthreshold levels of a different stimulus-type mask. For this reason, we cannot rule out the possibility that FRF mechanisms mediate the detection of our stimuli. For combinations involving CM masks, however, we propose that a process of contrast normalization renders the test stimulus insensitive to the mask stimulus.