Working-memory capacity, proactive interference, and divided attention: Limits on long-term memory retrieval

Two experiments examined how individual differences in working-memory capac ity (WM) relate to proactive interference (PI) susceptibility. We tested hi gh and low WM-span participants in a PI-buildup task under single-task or d ual-task ("load") conditions. In Experiment 1, a finger-tapping task was im posed during encoding and retrieval of each list; in Experiment 2, tapping was required during encoding or retrieval. In both experiments, low spans s howed greater PI than did high spans under no load, but groups showed equiv alent PI under divided attention. Load increased PI only for high spans, su ggesting they use attention at encoding and retrieval to combat PI. In Expe riment 2, only low spans showed a dual-task cost on List 1 memory, before P I built up. Results indicate a role for attentional processing, perhaps inh ibitory in nature, at encoding and retrieval, and are discussed with respec t to theories of WM and prefrontal cortex function.