Abstract
Visual working memory (VWM) is a limited resource that places constraints on how precisely encoded information can be recalled. The immense processing demands placed on VWM imply that information can quickly become outdated, thereby requiring updating mechanisms that ensure the contents of memory remain relevant to current task goals. Successful deallocation of resources from items that become obsolete is likely to be critical for maintaining the precision of those representations still in memory. Our experimental paradigm involved presenting two memory arrays of colored disks in sequence. The presentation of the second array was a cue to replace either one, or all, of the items from the first array previously encoded into memory. When compared to a condition that was matched in the total number of items presented, we predicted that successful updating would result in fewer actively maintained items, owing to the removal of pre-replacement features. Comparison of precision estimates between these two conditions should therefore provide a test of successful updating. A direct comparison between precision estimates was made difficult by a very small proportion of trials (~4%) on which participants incorrectly reported a pre-replacement feature, which we interpret as a failure to incorporate the information from the second display into memory. Once these trials were removed from analysis, precision estimates were consistent with deallocation of resources from pre-replacement features. We conclude that working memory can be efficiently updated when previous information becomes obsolete, but that this is a demanding active process that occasionally fails.
Acknowledgement: Wellcome Trust