Time-course and surround modulation of contrast masking in human vision
Time-course and surround modulation of contrast masking in human vision
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DOI：
10.1167/8.3.23
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发表时间：
2008-01-01
影响因子：
1.8
通讯作者：
Herzog, Michael H.
中科院分区：
文献类型：
--
作者：
Saarela, Toni P.;Herzog, Michael H.
对视觉刺激的神经和知觉反应可以被空间重叠和空间相邻的环境刺激抑制。我们在心理物理对比掩蔽实验中研究了这些抑制性相互作用的时间特征，使用Gabor和光栅刺激，空间频率为每度4个周期。我们发现掩膜的时间过程强烈依赖于掩膜的方向。最有趣的是，当目标在掩码之前或之后出现时，空间重叠的、等向掩码的掩码效果最强。这种掩蔽是短暂的，可能是由神经对掩蔽开始和抵消的反应引起的。在蒙版中加入环绕可以调节后向蒙版效果，但只有当目标和中央蒙版方向相同时才可以。我们的结果为环绕抑制机制提供了证据，该机制影响掩模开始时的瞬态响应，但不影响掩模偏移的响应。综上所述，这些结果证明了空间背景在视觉处理中的作用是如何严重依赖于刺激时间的。
Neural and perceptual responses to a visual stimulus can be suppressed by the addition of both spatially overlapping and spatially adjacent contextual stimuli. We investigated the temporal characteristics of these suppressive interactions in psychophysical contrast masking experiments using Gabor and grating stimuli with a spatial frequency of 4 cycles per degree. We found that the time course of masking strongly depended on mask orientation. Most interestingly, masking by a spatially overlaid, iso-oriented mask was strongest when the target was presented immediately before or immediately after the mask. This masking was transient, presumably caused by the neural responses to mask onset and offset. Adding a surround to the mask modulated the backward masking effect, but only when the target and the central mask were iso-oriented. Our results provide evidence for a surround suppression mechanism that affected the transient responses to the mask onset, but not the responses to the mask offset. Together, these results demonstrate how the effects of spatial context in visual processing critically depend on stimulus timing.