Extrapolating from parameters fitted to a restricted range of between-session intervals produces worse predictions than time-variant fits¶

Claim · All claims
Evidence · 1 study · associational r2 · q2
Currency · newest study 2026 · not yet checked against its sources · not reviewed by a person

Subclaims¶

q2 i? Models fitted only to 0–10 minute or 23.5–24.5 hour intervals predicted recall worse out-of-sample than any of the time-variant model fits. → Maarten van der Velde 2026

Evidence¶

Maarten van der Velde 2026¶

Maarten van der Velde, Florian Sense, Jelmer P. Borst & Hedderik van Rijn. (2026). Explaining forgetting at different timescales requires a time-variant forgetting function. npj Science of Learning. https://doi.org/10.1038/s41539-026-00447-1

q2 · i? · associational · r2

Cross-validated comparison of models fitted to restricted interval ranges (0–10 minutes, reflecting within-session intervals, or around 24 hours) against time-variant fits. The article reports "clear evidence that extrapolating from parameters fitted to a restricted range... produces worse model predictions."

"We found clear evidence that extrapolating from parameters fitted to a restricted range of between-session intervals (0–10 min or 24 hours; Fig.2b) produces worse model predictions than any of the time-variant model fits."

Discussion¶

Related Claims¶

• In 5-fold cross-validation, multi-bin time-variant model fits outperform single-bin fits, with diminishing returns beyond a 5-bin split and further gains from differentiating by learner and amount of practice — related
• Optimal ACT-R parameter values change systematically and predictably with the length of the between-session interval — a broader claim this one bears on
• Allowing ACT-R memory parameters to vary with the between-session interval produces a strong fit between model and recall data across timescales — a broader claim this one bears on
• A single time-invariant ACT-R forgetting function cannot simultaneously capture recall accuracy on short and long between-session intervals — a narrower finding that bears on this claim