Attentional Boost for Visual Working Memory: Concurrent Target Detection Improves Change Detection but Interferes with Continuous Estimation

Detecting a target stimulus in one task can improve the memory of materials presented concurrently for another task. This attentional boost effect has been tested predominantly with delayed recognition or recall as the memory task, which relied on long-term memory, and little is known about its influence on short-term or working memory. The present study confirmed that concurrent target detection improves the performance in a canonical working memory task, namely, a change detection task with a small set of well-defined color categories (Experiment 1) or with a larger set of more subtle shades of colors (Experiment 2). These experiments, however, did not produce attentional boost beyond a single-task setting, unlike previous studies testing long-term memory. Concurrent target detection also resulted in dual-task interference rather than attentional boost when precise color estimation was required in a continuous report task (Experiment 3). A model-based analysis of recall error indicated that that dual-task interference came from reduced number of items in working memory rather than lower memory precision of individual items when concurrent target detection was required. The present findings set a boundary condition and raised important questions as to the mechanisms behind the attentional boost effect for working memory. We propose that our findings raise the possibility that the ABE results from an enhanced transfer of WM content to LTM.