The Connection Between Associative Memory and Semantic Similarity: Evidence From Fan Experiments and Distributional Models.

Memory retrieval is prone to interference: when multiple concepts in memory match a given retrieval cue, recall becomes slower and less accurate. This has repeatedly been studied in fan effect experiments in which participants learn facts that are combinations of person-location pairs. These experiments manipulate the fan of a concept-the number of facts linked to it-establishing interference. The standard theoretical account invokes spreading activation: when a cue is linked to multiple memory traces, activation spreads across them, reducing the target's retrievability. We study whether this spreading activation is triggered only by explicitly learned associations or also by semantic similarity. We show that spreading activation in the rational analysis of memory is pointwise mutual information and that similarity in at least some vector-space models of meaning approximates the same quantity, which makes such models potentially formal implementations of the rational analysis of memory. In two behavioral experiments using Dutch-language stimuli, we first replicate the classical fan effect. Experiment 2 tests whether this interference effect can be elicited through semantic similarity alone, using pretrained word embeddings to construct semantic fans. We find that items in higher semantic-fan conditions are retrieved more slowly and less accurately, mirroring patterns from Experiment 1. In a simulation, we show that similarity in embedding spaces predicts retrieval difficulty in a manner consistent with rational models of memory. Together, these results formally connect vector-space models of meaning with the rational analysis of memory, and demonstrate that semantic similarity is sufficient to produce associative interference in memory.