Chen Siyi, Töllner Thomas, Müller Hermann J, Conci Markus
Department of Psychology, Ludwig-Maximilians-Universität München, Munich , Germany.
Graduate School of Systemic Neurosciences, Ludwig-Maximilians-Universität München, Munich , Germany.
J Neurophysiol. 2018 Jan 1;119(1):347-355. doi: 10.1152/jn.00469.2017. Epub 2017 Oct 25.
Completion of a partially occluded object requires that a representation of the whole is constructed based on the information provided by the physically specified parts of the stimulus. Such processes of amodal completion rely on the generation and maintenance of a mental image that renders the completed object in visual working memory (VWM). The present study examined this relationship between VWM storage and processes of object completion. We recorded event-related potentials to track VWM maintenance by means of the contralateral delay activity (CDA) during a change detection task in which composite objects (notched shapes abutting an occluding shape) to be memorized were primed to induce either a globally completed object or a noncompleted, mosaic representation. The results revealed an effect of completion in VWM despite physically identical visual input: change detection was more accurate for completed compared with mosaic representations when observers were required to memorize two objects, and these differences were reduced with four memorized items. At the electrophysiological level, globally completed (vs. mosaic) objects gave rise to a corresponding increase in CDA amplitudes. These results indicate that although incorporating the occluded portions of the presented shapes requires mnemonic resources, the complete object representations thus formed in VWM improve change detection performance by providing a more simple, regular shape. Overall, these findings demonstrate that mechanisms of object completion modulate VWM, with the memory load being determined by the structured representations of the memorized stimuli. NEW & NOTEWORTHY This study shows that completion of partially occluded objects requires visual working memory (VWM) resources. In the experiment reported, we induced observers to memorize a given visual input either as completed or as noncompleted objects. The results revealed both a behavioral performance advantage for completed vs. noncompleted objects despite physically identical input, and an associated modulation of an electrophysiological component that reflects VWM object retention, thus indicating that constructing an integrated object consumes mnemonic resources.
完成一个部分被遮挡的物体需要基于刺激的物理指定部分所提供的信息构建一个整体的表征。这种无模态完成过程依赖于在视觉工作记忆（VWM）中生成并维持一个呈现完整物体的心理意象。本研究考察了VWM存储与物体完成过程之间的这种关系。在一个变化检测任务中，我们记录了事件相关电位，通过对侧延迟活动（CDA）来追踪VWM维持，在该任务中，要记忆的复合物体（与遮挡形状邻接的有缺口形状）被启动以诱导出一个全局完整的物体或一个未完成的镶嵌表征。结果显示，尽管视觉输入在物理上相同，但在VWM中存在完成效应：当观察者需要记忆两个物体时，与镶嵌表征相比，完成表征的变化检测更准确，而这些差异在记忆四个项目时减小。在电生理水平上，全局完成（相对于镶嵌）的物体导致CDA振幅相应增加。这些结果表明，尽管纳入呈现形状的被遮挡部分需要记忆资源，但由此在VWM中形成的完整物体表征通过提供更简单、规则的形状提高了变化检测性能。总体而言，这些发现表明物体完成机制调节VWM，记忆负荷由所记忆刺激的结构化表征决定。新内容与值得注意之处 本研究表明，完成部分被遮挡的物体需要视觉工作记忆（VWM）资源。在报告的实验中，我们诱导观察者将给定的视觉输入记忆为已完成或未完成的物体。结果显示，尽管输入在物理上相同，但已完成物体相对于未完成物体在行为表现上具有优势，并且反映VWM物体保持的电生理成分也有相关调制，从而表明构建一个整合物体消耗记忆资源。
