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. |