Updating visual working memory is both object-based and feature-selective
Hyunyoung Park & Adriane E. Seiffert
Vanderbilt University

How do we update visual working memory? When modifying our memory of an object to integrate new information with stored information, do we use an object-based process or a feature-based process? Previous work has suggested that updating is not object-based, but rather feature-selective, because people selectively update one feature of a memorized object without refreshing the memory of other features of the object (Ko & Seiffert, 2009 Mem Cognit). To test whether updating shows any object-based benefit, we asked participants to update two features of their visual working memory of either one object or two objects. Participants memorized a display composed of three colored, oriented bars in three different locations. The display was followed by a cue instructing participants to update their memory of one feature of the object at the same location as the cue. To manipulate whether one or two objects were updated, a second cue either appeared at the same or different bar location as the first cue. Also, the two cues were either the same feature or different features. After the cues, a single bar probe appeared at one of the three bar locations. Participants indicated whether the probe matched their memory. The facilitation effect of updating features did not spread to the other feature of the cued object or features of other objects, for both one object (interaction F(1,24)=21.9, p<.001) and two-object (interaction F(1,24)=7.35, p<.013) updating. This was consistent with previous results showing feature-selective mechanism in updating. However, when the updated object was probed, participants performed more accurately when updating one object than two objects (F(1,24)=29.7, p<.001), showing evidence for an object-based mechanism. In addition, the feature-selective facilitation effect was significantly larger in one object updating than two-object updating (F(1,24)=6.30, p<.02). Taken together, these results suggested that updating relies on both object-based and feature-selective mechanisms.