Disentangling feedforward versus feedback processing in numerosity representation
Disentangling feedforward versus feedback processing in numerosity representation
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DOI：
10.1016/j.cortex.2020.11.013
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发表时间：
2021-01-04
期刊：
影响因子：
3.6
通讯作者：
Park, Joonkoo
中科院分区：
文献类型：
--
作者：
Fornaciai, Michele;Park, Joonkoo
数量是外部环境的一个基本方面，需要以有效的方式指导我们的行为。以往的研究表明，在早期的视皮层，数字加工至少涉及两个时间阶段(类似于100毫秒和类似于刺激开始后的150毫秒)。一种可能性是，这两个阶段反映了最初的前馈处理，随后是来自更高级别皮质区域的反馈信号，这些反馈信号是将视觉输入分割成定义数量的感知单元的基础。或者，多个阶段的前馈处理可以逐步精炼输入，从而得到分段表示。在这里，我们通过利用连通性错觉(即，对成对连通点的系统低估)、后向掩蔽(以抑制反馈信号)和序列依赖(即，使刺激看起来更类似于其前一个刺激的知觉偏差)来区分这两个假设。我们的结果表明，一个连通的点阵基于其虚幻的感知来偏向后续点阵的数字表示，而不管它是可见的还是被掩蔽抑制的。这些发现表明，反馈处理对于产生知觉数量的知觉分割并不是严格必要的，而是表明前馈活动的不同阶段可能携带低和高空间频率信息足以在早期视觉区域创建数量表征。(C)2020爱思唯尔有限公司。保留所有权利。
Numerosity is a fundamental aspect of the external environment, needed to guide our behavior in an effective manner. Previous studies show that numerosity processing involves at least two temporal stages (similar to 100 and similar to 150 msec after stimulus onset) in early visual cortex. One possibility is that the two stages reflect an initial feedforward processing followed by feedback signals from higher-order cortical areas that underlie segmentation of visual inputs into perceptual units that define numerosity. Alternatively, multiple stages of feedforward processing might progressively refine the input leading to the segmented representation. Here, we distinguish these two hypotheses by exploiting the connectedness illusion (i.e., the systematic underestimation of pairwise-connected dots), backward masking (to suppress feedback signals), and serial dependence (i.e., a perceptual bias making a stimulus appear to be more similar to its preceding one). Our results show that a connected dot array biases the numerosity representation of the subsequent dot array based on its illusory perception, irrespective of whether it is visible or suppressed by masking. These findings demonstrate that feedback processing is not strictly necessary for the perceptual segmentation that gives rise to perceived numerosity, and instead suggest that different stages of feedforward activity presumably carrying low and high spatial frequency information are sufficient to create a numerosity representation in early visual areas. (C) 2020 Elsevier Ltd. All rights reserved.