Helen Wills Neuroscience Institute, University of California-Berkeley, Berkeley, CA, USA.
Department of Psychology, University of California-Berkeley, Berkeley, CA, USA.
Q J Exp Psychol (Hove). 2020 Nov;73(11):1949-1968. doi: 10.1177/1747021820934990. Epub 2020 Jul 7.
Mnemonic precision is an important aspect of visual working memory (WM). Here, we probed mechanisms that affect precision for spatial (size) and non-spatial (colour) features of an object, and whether these features are encoded and/or stored separately in WM. We probed precision at the -that is, whether different features of a single object are represented separately or together in WM-and the -that is, whether different features across a set of sequentially presented objects are represented in the same or different WM stores. By manipulating whether stimuli were encoded by the left and/or right hemisphere, we gained further insights into how objects are represented in WM. At the feature-level, we tested whether recall fidelity for the two features of an object fluctuated in tandem from trial to trial. We observed no significant coupling under either central or lateralized encoding, supporting the claim of parallel feature channels at encoding. At the level of WM storage of a set of objects, we found asymmetric feature interference under central encoding, whereby an increase in colour load led to a decrease in size precision. When objects were encoded by a single hemisphere, however, we found largely independent feature stores. Precision for size was more resistant to interference from the size of another object under right-hemisphere encoding; by contrast, precision for colour did not differ across hemispheres, suggesting a more distributed WM store. These findings suggest that distinct features of a single object are represented separately but are then partially integrated during maintenance of a set of sequentially presented objects.
记忆精度是视觉工作记忆（WM）的一个重要方面。在这里，我们探讨了影响空间（大小）和非空间（颜色）特征精度的机制，以及这些特征是否在 WM 中分别编码和/或存储。我们在 - 即单个物体的不同特征是在 WM 中分别表示还是一起表示- 和 - 即一组连续呈现的物体的不同特征是在相同还是不同的 WM 存储中表示- 方面探测了精度。通过操纵刺激是由左半球和/或右半球编码的，我们进一步了解了物体在 WM 中的表示方式。在特征水平上，我们测试了一个物体的两个特征在每次试验中的回忆保真度是否同步波动。无论是在中央编码还是偏侧化编码下，我们都没有观察到明显的耦合，这支持了在编码时存在并行特征通道的说法。在一组物体的 WM 存储水平上，我们发现中央编码下存在不对称的特征干扰，即颜色负载的增加会导致大小精度的降低。然而，当物体由单个半球编码时，我们发现了很大程度上独立的特征存储。在右半球编码下，大小的干扰对大小精度的影响较小；相比之下，颜色的精度在半球之间没有差异，这表明 WM 存储更为分散。这些发现表明，单个物体的不同特征是分别表示的，但在一组连续呈现的物体的保持过程中会部分整合。
