Center for Mind/Brain Sciences, University of Trento, Rovereto, Italy.
Department of Psychology and Cognitive Science, University of Trento, Rovereto, Italy.
PLoS One. 2022 Mar 2;17(3):e0264127. doi: 10.1371/journal.pone.0264127. eCollection 2022.
While zebrafish represent an important model for the study of the visual system, visual perception in this species is still less investigated than in other teleost fish. In this work, we validated for zebrafish two versions of a visual discrimination learning task, which is based on the motivation to reach food and companions. Using this task, we investigated zebrafish ability to discriminate between two different shape pairs (i.e., disk vs. cross and full vs. amputated disk). Once zebrafish were successfully trained to discriminate a full from an amputated disk, we also tested their ability to visually complete partially occluded objects (amodal completion). After training, animals were presented with two amputated disks. In these test stimuli, another shape was either exactly juxtaposed or only placed close to the missing sectors of the disk. Only the former stimulus should elicit amodal completion. In human observers, this stimulus causes the impression that the other shape is occluding the missing sector of the disk, which is thus perceived as a complete, although partially hidden, disk. In line with our predictions, fish reinforced on the full disk chose the stimulus eliciting amodal completion, while fish reinforced on the amputated disk chose the other stimulus. This represents the first demonstration of amodal completion perception in zebrafish. Moreover, our results also indicated that a specific shape pair (disk vs. cross) might be particularly difficult to discriminate for this species, confirming previous reports obtained with different procedures.
虽然斑马鱼是研究视觉系统的重要模型，但与其他硬骨鱼相比，这种鱼的视觉感知仍较少被研究。在这项工作中，我们验证了两种基于觅食和同伴动机的视觉辨别学习任务在斑马鱼中的应用。使用该任务，我们研究了斑马鱼辨别两种不同形状对（即圆盘与十字和完整圆盘与截断圆盘）的能力。一旦斑马鱼成功地学会了区分完整圆盘和截断圆盘，我们还测试了它们对部分遮挡物体进行视觉完形感知（即模态补缺）的能力。训练后，动物会被呈现两个截断圆盘。在这些测试刺激中，另一个形状要么完全相邻，要么仅放置在圆盘缺失区域附近。只有前者应该引起模态补缺的感觉。在人类观察者中，这种刺激会让人感觉另一个形状正在遮挡圆盘缺失的部分，从而使圆盘看起来是完整的，尽管部分隐藏。与我们的预测一致，在完整圆盘上受到强化的鱼选择了引起模态补缺的刺激，而在截断圆盘上受到强化的鱼选择了另一个刺激。这是在斑马鱼中首次证明模态补缺感知的存在。此外，我们的结果还表明，对于这种鱼类来说，特定的形状对（圆盘与十字）可能特别难以区分，这与使用不同程序获得的先前报告一致。
