Abstract
The severely limited capacity of visual working memory is thought to result from a fixed storage capacity, rather than limitations at encoding or retrieval. Thus, most investigations of working memory have focused on understanding the storage systemits capacity, its flexibility, and the units over which it operates. Little work has investigated how items are retrieved from working memory, with retrieval typically seen as straightforward, since items in working memory are actively maintained and thus directly accessible. Here we show that working memory is limited not only by storage capacity but also by failures to retrieve successfully maintained items. Specifically, we asked participants to remember the colors of five briefly presented circles. Participants were first asked to report a randomly probed items color by performing a continuous report judgment. Many responses deviated from the true color, reflecting limitations on memory that are typically interpreted as showing that little or no information was maintained about the probed item. To determine whether participants might know information about the item despite reporting an incorrect value, we asked participants about the probed item a second time: Participants were given two color choices, one correct and the other a foil, and had to choose the correct color. To avoid anchoring, the choices were equidistant in color from the participants first response. If everything a participant knows about an item is captured by the first response, participants should be at chance on this judgment. However, participants chose correctly at greater than chance rates (63%, p<.001) even when the first response was highly inaccurate (>90째 error) (61%, p<.001). These results suggest that typical paradigms underestimate how many items participants can maintain in memory. In addition, they demonstrate an important role for retrieval in working memory, sometimes items that are successfully stored are not successfully reported.
Meeting abstract presented at VSS 2014