Can people make perfect use of task-relevant information in working memory (WM)? Specifically, when questioned about an item in an array that does not happen to be in WM, can participants take into account other items that are in WM, eliminating them as response candidates? To address this question, an ideal-responder model that assumes perfect use of items in a capacity-limited WM was tested against a minimal-responder model that assumes use of only information about the queried item. Three different WM tasks were adopted: change detection, identity recognition, and location recognition. The change-detection task produced benchmark WM results. The 2 novel tasks showed that only the minimal responder model provided convergence with this benchmark. This finding was replicable even when the change-detection task was replaced by a feature-switch detection task. Thus, it appears that people do not make full use of information in WM.