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Beyond Frequency and Recency: An Entropy-Based Extension for Modeling Memory Retrieval in Dynamic Environments
DescriptionThis study extends the ACT-R base-level learning equation by incorporating environmental uncertainty, observation duration, and individual learning patterns to better model human memory retrieval in dynamic, multi-object environments. We hypothesize that retrieval efficiency depends not only on frequency and recency of interactions but also on scene entropy, time spent observing, and a learning pattern parameter (α). Using a household task scenario in the AI2-THOR simulator, we analyzed search times as proxies for memory access. Our modified equation integrates entropy to reflect visual uncertainty, scales decay by observation duration, and includes α to capture task-specific learning dynamics. Results from eight participants revealed distinct retrieval patterns (e.g., Increasing–Decreasing vs. Decreasing–Increasing search times) related to prior experience. Compared to the original ACT-R model (MAE = 0.3135, correlation = 0.4568), our modified equation achieved a lower average MAE of 0.2629 and a higher correlation of 0.6126 with observed behavior, demonstrating improved predictive accuracy. These findings offer a stronger foundation for modeling memory retrieval and have implications for adaptive user interfaces, training systems, and assistive agents that rely on understanding human memory performance in visually complex settings.