Fornaciai Michele, Park Joonkoo
Department of Psychological & Brain Sciences, University of Massachusetts, Amherst, MA, USA.
Commonwealth Honors College, University of Massachusetts, Amherst, MA, USA.
J Vis. 2018 Sep 4;18(9):15. doi: 10.1167/18.9.15.
Our conscious experience of the external world is remarkably stable and seamless, despite the intrinsically discontinuous and noisy nature of sensory information. Serial dependencies in visual perception-reflecting attractive biases making a current stimulus to appear more similar to previous ones-have been recently hypothesized to be involved in perceptual continuity. However, while these effects have been observed across a variety of visual features and at the neural level, several aspects of serial dependence and how it generalizes across visual dimensions is still unknown. Here we explore the behavioral signature of serial dependence in numerosity perception by assessing how the perceived numerosity of dot-array stimuli is biased by a task-irrelevant "inducer" stimulus presented before task-relevant stimuli. First, although prior work suggests that numerosity perception starts in the subcortex, the current study rules out a possible involvement of subcortical processing in serial dependence, confirming that the effect likely starts in the visual cortex. Second, we show that the effect is coarsely spatially localized to the position of the inducer stimulus. Third, we demonstrate that the effect is present even with a stimulus presentation procedure minimizing the involvement of post-perceptual processes, but only when participants actively pay attention to the inducer stimulus. Overall, these results provide a comprehensive characterization of serial dependencies in numerosity perception, demonstrating that attractive biases occur by means of spatially localized attentional modulations of early sensory activity.
尽管感官信息本质上是不连续且嘈杂的，但我们对外部世界的有意识体验却非常稳定且无缝。视觉感知中的序列依赖性——反映出一种吸引偏差，使当前刺激看起来更类似于先前的刺激——最近被假设与感知连续性有关。然而，虽然这些效应已在各种视觉特征和神经层面被观察到，但序列依赖性的几个方面及其如何在视觉维度上泛化仍然未知。在这里，我们通过评估与任务相关的刺激之前呈现的与任务无关的“诱导”刺激如何影响点阵刺激的感知数量，来探索数量感知中序列依赖性的行为特征。首先，尽管先前的研究表明数量感知始于皮层下，但当前研究排除了皮层下处理在序列依赖性中的可能参与，证实这种效应可能始于视觉皮层。其次，我们表明这种效应在空间上大致定位于诱导刺激的位置。第三，我们证明即使在最小化感知后过程参与的刺激呈现程序下，这种效应仍然存在，但前提是参与者积极关注诱导刺激。总体而言，这些结果全面描述了数量感知中的序列依赖性，表明吸引偏差是通过早期感觉活动的空间局部注意调制产生的。
