Symmetry: Modeling the Effects of Masking Noise, Axial Cueing and Salience
Symmetry: Modeling the Effects of Masking Noise, Axial Cueing and Salience
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DOI：
10.1371/journal.pone.0009840
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发表时间：
2010-04-06
期刊：
影响因子：
3.7
通讯作者：
Tyler, Christopher W.
中科院分区：
文献类型：
--
作者：
Chen, Chien-Chung;Tyler, Christopher W.
对称检测是模式处理中一个有趣的探索，因为它需要在没有先验识别的情况下匹配新的模式。然而，有证据表明，轴位置的先验知识在对称性检测中起着重要作用。研究了在噪声掩蔽条件下，对称轴的先验信息对对称性检测的影响。目标刺激是随机点显示，其结构为围绕垂直轴、水平轴或对角轴对称，并通过围绕6度直径圆均匀分布的8个孔(1.2度直径)观看。关于轴方向的信息是通过(1)在试验前提示轴方向和(2)通过包括或排除噪声孔内的轴区域来改变轴突出度来处理的。对于目标和掩蔽噪声密度的范围，对称性的正确检测百分比被测量为。阈值-噪声密度函数在低噪声密度下是平坦的，在超过临界密度时以0.75-0.8的斜率增加。轴线提示使目标阈值在所有噪声密度下降低2-4倍，而轴线突显仅在高噪声密度下有影响。我们的结果与对称性检测的理想观测器或信噪比解释不一致，但可以用多通道模型来解释，即每个通道的响应是一组早期对称检测器的响应的非线性变换与外部和内部噪声源之和的比率。
Symmetry detection is an interesting probe of pattern processing because it requires the matching of novel patterns without the benefit of prior recognition. However, there is evidence that prior knowledge of the axis location plays an important role in symmetry detection. We investigated how the prior information about the symmetry axis affects symmetry detection under noise-masking conditions. The target stimuli were random-dot displays structured to be symmetric about vertical, horizontal, or diagonal axes and viewed through eight apertures (1.2 degrees diameter) evenly distributed around a 6 degrees diameter circle. The information about axis orientation was manipulated by (1) cueing of axis orientation before the trial and (2) varying axis salience by including or excluding the axis region within the noise apertures. The percentage of correct detection of the symmetry was measured at for a range of both target and masking noise densities. The threshold vs. noise density function was flat at low noise density and increased with a slope of 0.75-0.8 beyond a critical density. Axis cueing reduced the target threshold 2-4fold at all noise densities while axis salience had an effect only at high noise density. Our results are inconsistent with an ideal observer or signal-to-noise account of symmetry detection but can be explained by a multiple-channel model is which the response in each channel is the ratio between the nonlinear transform of the responses of sets of early symmetry detectors and the sum of external and intrinsic sources of noise.