Semantic similarity among autobiographical memories is associated with rumination.

Depressive rumination is characterized by repetitive dwelling on one or more self-relevant, past-oriented topics. However, little empirical evidence links depressive rumination to the perseveration of specific themes in autobiographical memory (AM) retrieval. This study examined whether ruminators are more likely to retrieve semantically overlapping AMs across different times and locations using the experience sampling method (ESM). Participants (N = 58 Japanese-speaking university students) generated AMs in response to negative and positive cues three times daily for seven days. In total, 3063 AMs were collected and analyzed. For each participant, we computed cosine similarity to quantify semantic overlap among the reported AMs. The results indicated that individuals with higher levels of rumination exhibited greater semantic overlap among negative AMs (r = 0.33), suggesting that ruminators' AMs tended to revolve around similar topics and themes across different cues and assessment occasions. These findings suggest that semantic overlap serves as an underlying mechanism of depressive rumination (and vice versa), wherein different cues activate a specific network that encodes similar or identical negative memory representations.