Abstract
Working memory capacity has long been the subject of intense research interest, but few studies have systematically investigated the dependence of capacity on memory load that exceeds our retention abilities. Under this real-world scenario, WM performance typically declines beyond a critical load among low-capacity subjects, a phenomenon known as working memory overload. We used a frontoparietal cortical model to test the hypothesis that high-capacity subjects select a manageable number of items for storage, thereby avoiding overload. The model accounts for behavioural and electrophysiological data from high-capacity subjects in a parameter regime where competitive encoding in its prefrontal network selects items for storage, inter-aerial projections sustain their representations after stimulus offset, and weak dynamics in its parietal network limit their mutual interference. Violation of these principles accounts for these data among low-capacity subjects, implying that poor working memory performance reflects poor control over fronto-parietal circuitry, and making testable predictions for experiments.