Grating and plaid masks indicate linear summation in a contrast gain pool
Grating and plaid masks indicate linear summation in a contrast gain pool
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DOI：
10.1167/4.12.7
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发表时间：
2004-01-01
影响因子：
1.8
通讯作者：
Meese, TS
中科院分区：
文献类型：
--
作者：
Holmes, DJ;Meese, TS
在人类视觉中，对图像中每个小区域的亮度对比度的响应由更全局的过程控制，其中抑制信号在空间频率和方向带上被合并。但是，在抑制池中，是什么规则支配着刺激成分之间的总和呢？我们通过扩展基座加图案掩模范例来解决这个问题，以使用具有多达三个掩模分量的刺激：垂直1 c/deg基座，加上由光栅（取向=-45度）或格子（取向= +/-45度）制成的图案掩模，其中分量空间频率为3 c/deg。两种类型的图案掩模的总对比度固定在20%（即，格纹组分对比度为10%）。我们发现，这两种掩模都以完全相同的方式转换了传统的铲斗函数（阈值与无图案掩模的基座对比度）：铲斗区域升高并向右移动，但铲斗柄重叠。两个图案掩模的这种等效性表明，在掩模阶段之前，格子图案分量之间的对比度总和是完全线性的。此外，图案掩模没有驱动检测机制高于其检测阈值，因为它们没有消除基座的促进作用（Foley，1994）。因此，模式掩蔽不能归因于通道内掩蔽，这表明在抑制性对比度增益池内发生对比度信号的线性求和。我们提出了一个定量模型的影响，并讨论了神经生理模型的过程中的影响。
In human vision, the response to luminance contrast at each small region in the image is controlled by a more global process where suppressive signals are pooled over spatial frequency and orientation bands. But what rules govern summation among stimulus components within the suppressive pool? We addressed this question by extending a pedestal plus pattern mask paradigm to use a stimulus with up to three mask components: a vertical 1 c/deg pedestal, plus pattern masks made from either a grating (orientation = -45degrees) or a plaid (orientation = +/-45degrees), with component spatial frequency of 3 c/deg. The overall contrast of both types of pattern mask was fixed at 20% (i.e., plaid component contrasts were 10%). We found that both of these masks transformed conventional dipper functions (threshold vs. pedestal contrast with no pattern mask) in exactly the same way: The dipper region was raised and shifted to the right, but the dipper handles superimposed. This equivalence of the two pattern masks indicates that contrast summation between the plaid components was perfectly linear prior to the masking stage. Furthermore, the pattern masks did not drive the detecting mechanism above its detection threshold because they did not abolish facilitation by the pedestal (Foley, 1994). Therefore, the pattern masking could not be attributed to within-channel masking, suggesting that linear summation of contrast signals takes place within a suppressive contrast gain pool. We present a quantitative model of the effects and discuss the implications for neurophysiological models of the process.