Alais David, Leung Johahn, Van der Burg Erik
School of Psychology, The University of Sydney, New South Wales 2006, Australia, and
School of Psychology, The University of Sydney, New South Wales 2006, Australia, and.
J Neurosci. 2017 Apr 19;37(16):4381-4390. doi: 10.1523/JNEUROSCI.4601-15.2017. Epub 2017 Mar 22.
Recent work from several groups has shown that perception of various visual attributes in human observers at a given moment is biased toward what was recently seen. This positive serial dependency is a kind of temporal averaging that exploits short-term correlations in visual scenes to reduce noise and stabilize perception. To date, this stabilizing "continuity field" has been demonstrated on stable visual attributes such as orientation and face identity, yet it would be counterproductive to apply it to dynamic attributes in which change sensitivity is needed. Here, we tested this using motion direction discrimination and predict a negative perceptual dependency: a contrastive relationship that enhances sensitivity to change. Surprisingly, our data showed a cubic-like pattern of dependencies with positive and negative components. By interleaving various stimulus combinations, we separated the components and isolated a positive perceptual dependency for motion and a negative dependency for orientation. A weighted linear sum of the separate dependencies described the original cubic pattern well. The positive dependency for motion shows an integrative perceptual effect and was unexpected, although it is consistent with work on motion priming. These findings suggest that a perception-stabilizing continuity field occurs pervasively, occurring even when it obscures sensitivity to dynamic stimuli. Recent studies show that visual perception at a given moment is not entirely veridical, but rather biased toward recently seen stimuli: a positive serial dependency. This temporal smoothing process helps perceptual continuity by preserving stable aspects of the visual scene over time, yet, for dynamic stimuli, temporal smoothing would blur dynamics and reduce sensitivity to change. We tested whether this process is selective for stable attributes by examining dependencies in motion perception. We found a clear positive dependency for motion, suggesting that positive perceptual dependencies are pervasive. We also found a concurrent negative (contrastive) dependency for orientation. Both dependencies combined linearly to determine perception, showing that the brain can calculate contrastive and integrative dependencies simultaneously from recent stimulus history when making perceptual decisions.
几个研究团队最近的工作表明，人类观察者在某一时刻对各种视觉属性的感知会偏向于最近看到的事物。这种正向序列依赖性是一种时间平均，它利用视觉场景中的短期相关性来减少噪声并稳定感知。迄今为止，这种稳定的“连续性场”已在诸如方向和面部识别等稳定视觉属性上得到证实，但将其应用于需要变化敏感性的动态属性上可能会适得其反。在这里，我们通过运动方向辨别对此进行了测试，并预测会出现负向感知依赖性：一种增强对变化敏感性的对比关系。令人惊讶的是，我们的数据显示出具有正负成分的类似立方的依赖性模式。通过交错各种刺激组合，我们分离了这些成分，并分离出了运动的正向感知依赖性和方向的负向依赖性。单独依赖性的加权线性和很好地描述了原始的立方模式。运动的正向依赖性显示出一种整合性的感知效应，这是出乎意料的，尽管它与运动启动的研究结果一致。这些发现表明，一种稳定感知的连续性场普遍存在，即使它会掩盖对动态刺激的敏感性。最近的研究表明，某一时刻的视觉感知并非完全如实反映，而是偏向于最近看到的刺激：一种正向序列依赖性。这种时间平滑过程通过随着时间保留视觉场景的稳定方面来帮助感知连续性，然而，对于动态刺激，时间平滑会模糊动态并降低对变化的敏感性。我们通过检查运动感知中的依赖性来测试这个过程是否对稳定属性具有选择性。我们发现运动有明显的正向依赖性，表明正向感知依赖性是普遍存在的。我们还发现了方向的并发负向（对比）依赖性。两种依赖性线性组合以确定感知，表明大脑在做出感知决策时可以根据最近的刺激历史同时计算对比性和整合性依赖性。
