Individual Variation in Encoding Strategy Optimization in Visual Working Memory: Evidence From a Change Detection Task

Abstract

Extensive research has shown that differences in cognitive ability predict working memory (WM) performance. However, strategy use may also explain individual differences in WM. Here we explored the degree to which individuals use the optimal encoding strategy in visual WM. Participants searched for a target that changed between two alternating displays that cycled until response. Critically, participants were free to choose between two available targets (one red, one blue), and the ratio of red to blue items varied randomly across trials. Therefore, the optimal strategy was to selectively encode items in the smaller colour subset. Our main findings (Experiment 1 and a larger-sample replication in Experiment 5) showed a general tendency to choose the optimal (small subset) target, but there were large individual differences in strategy choice, with many participants using sub-optimal strategies. Further, we found some evidence that WM ability predicts strategy use. Experiment 2 showed that strategy use was not stable over time. Many participants spontaneously shifted to highly-optimal target choices, suggesting a sudden discovery of the optimal strategy. Experiment 3 confirmed the importance of explicit knowledge in strategy choice. Informing participants about the optimal strategy induced a large strategy improvement. Moreover, optimally-performing participants demonstrated explicit awareness of the optimal strategy. Experiment 4 showed that, even under greater task demands, when participants viewed the displays only once, strategy use was still sub-optimal. Our findings highlight strategy choice as an important source of individual variation, and therefore should be considered alongside ability to fully understand differences in WM performance.

Joint contributions of preview and task instructions on visual search strategy selection

“…Consequently, the awareness score might not accurately reflect their search behaviors during the experiment. More importantly, the current version of the awareness check lacked temporal information regarding when participants were aware of such an optimal strategy (see Lin & Leber, 2024).…”