Previous research has provided rich evidence that a set of visual objects can be encoded in isolation along with their exact coordinate positions as well as a global configuration that provides a network of interrelated spatial information. However, much less data is available on how unoccupied locations are encoded and maintained in memory. We tested this ability in adults using a novel paradigm that involved both empty and filled locations and required participants to monitor the addition or deletion of an item, which occurred 50% of the time. Crucially, a number of locations remained hidden to the participant—thus, information on the absence of an item at a location could not be inferred from the presence of items elsewhere. We used eye-tracking to measure the proportion of target looking during encoding and the amount of pupil dilation during memory retention. Participants looked significantly longer at filled compared with empty targets, and target looking during encoding only predicted accuracy in case of filled targets. Increased pupil dilation was observed in response to an increasing number of items, while pupil diameter was unaffected by the number of empty locations. In addition, participants made significantly more errors in the conditions that involved the representation of an empty location. Our findings support the view that human adults encode exact coordinates of items in memory. In contrast, we suggest that empty locations are represented as a property of the global configuration of items and empty space, and not as independent units of information.

先前的研究提供了丰富的证据，表明一组视觉对象可以与它们的精确坐标位置以及提供相互关联的空间信息网络的全局配置一起单独编码。然而，关于如何在内存中编码和维护未占用位置的可用数据要少得多。我们使用一种新的范式在成人中测试了这种能力，该范式涉及空的和填充的位置，并要求参与者监控一个项目的添加或删除，这在 50% 的时间内发生。至关重要的是，许多位置对参与者来说仍然是隐藏的——因此，无法从其他地方的物品的存在中推断出某个位置没有物品的信息。我们使用眼动追踪来测量编码期间目标注视的比例和记忆保留期间的瞳孔扩张量。与空目标相比，参与者在填充时注视的时间明显更长，并且在编码期间查看目标仅在填充目标的情况下预测准确性。随着项目数量的增加，观察到瞳孔扩张增加，而瞳孔直径不受空位置数量的影响。此外，参与者在涉及空位置表示的条件下犯了更多错误。我们的研究结果支持人类成年人对记忆中项目的精确坐标进行编码的观点。相反，我们建议将空位置表示为项目和空空间的全局配置的属性，而不是作为独立的信息单元。