What Remains after Factual Forgetting? History-Conditioned Access

We show that factual learning leaves a residual parameter state that shapes subsequent learning even after the learned answers are no longer expressed. Across twelve Pythia-410M training runs, we randomize which facts receive training before interference, then test updates that train only on other facts. Prior exposure increases the update-induced change in exact-answer accuracy by 5.03 percentage points over the full fact panel. Among current failures, previously acquired facts recover more often than never-exposed facts, including within-fact and margin-deficit-adjusted comparisons; history-dependent recovery and faster relearning recur in Pythia-1.4B and Qwen2.5-0.5B. A correct answer may start closer to overtaking its competitors, or an update may push it further toward that threshold. Starting gaps explain much of the recovery ordering under random parameter displacement, but factual updates also depend on learned associations: label correctness changes the recovery gap more for previously trained support facts than for fresh ones. We measure this sensitivity before training by comparing the gradient directions that raise the answer score and lower support loss. Exposure changes this pre-update QKV tangent geometry, improving prediction of the cue-by-label margin effect after ten real training steps at two Pythia scales. To test the influence of historical parameters directly, we transplant blocks from donors with different query–answer assignments into a common recipient. Across six recipient–donor triplets, answer preferences follow the donor's assignments, including ones it no longer expresses, and respond differently to later training. A separate predictor links geometry to transplantation: fitted only on exposure histories, it partly predicts how replacing blocks changes an update's effect on answer scores in three new triplets, reducing error by 9.69% relative to assuming that replacement leaves this response unchanged. Residual factual memory thus concerns both present accessibility and how past learning conditions future updates.