Department of Psychology, City University, London, United Kingdom.
PLoS One. 2009 Dec 2;4(12):e8123. doi: 10.1371/journal.pone.0008123.
Contrast discrimination for an image is usually harder if another image is superimposed on top. We asked whether such contrast masking may be enhanced or relieved depending on cues promoting integration of both images as a single pattern, versus segmentation into two independent components.
METHODOLOGY & PRINCIPAL FINDINGS: Contrast discrimination thresholds for a foveal test grating were sharply elevated in the presence of a perfectly overlapping orthogonally-oriented mask grating. However thresholds returned to the unmasked baseline when a surround grating was added, having the same orientation and phase of either the test or mask grating. Both such masking and 'unmasking' effects were much stronger for moving than static stimuli.
CONCLUSIONS & SIGNIFICANCE: Our results suggest that common-fate motion reinforces the perception of a single coherent plaid pattern, while the surround helps to identify each component independently, thus peeling the plaid apart again. These results challenge current models of early vision, suggesting that higher-level surface organization influences contrast encoding, determining whether the contrast of a grating may be recovered independently from that of its mask.
如果在图像上叠加另一幅图像，那么对该图像的对比度进行辨别通常会更难。我们想知道，根据促进将两幅图像整合为单个图案的线索，而不是将其分割为两个独立的组件，这种对比度掩蔽是否会增强或减轻。
在存在完全重叠的正交掩蔽光栅的情况下，中央凹测试光栅的对比度辨别阈值急剧升高。但是，当添加具有与测试或掩蔽光栅相同的取向和相位的环绕光栅时，阈值会恢复到未掩蔽的基线。对于运动刺激而言，这两种掩蔽和“去掩蔽”效应都要强得多。
我们的结果表明，共同命运的运动增强了对单个一致的棋盘格图案的感知，而周围环境有助于独立识别每个组件，从而再次将棋盘格分开。这些结果挑战了早期视觉的现有模型，表明高层的表面组织会影响对比度编码，从而决定光栅的对比度是否可以与其掩蔽的对比度独立恢复。
