A single time-invariant ACT-R forgetting function cannot simultaneously capture recall accuracy on short and long between-session intervals¶

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? When an ACT-R model is fitted to short intervals it under-predicts retention at longer intervals, and when fitted to longer intervals it over-predicts accuracy on short intervals. → 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

Model-fitting analysis of naturalistic recall data from an adaptive fact-learning system. The standard ACT-R model fitted to intervals up to 10 minutes became "far too pessimistic" at longer intervals, and "the same model fitted to longer intervals overestimates accuracy on short intervals (Fig.1c)." No effect size is printed.

"while the same model fitted to longer intervals overestimates accuracy on short intervals (Fig.1c)."

Discussion¶

Related Claims¶

• Extrapolating from parameters fitted to a restricted range of between-session intervals produces worse predictions than time-variant fits — 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 — related
• ISI effects on recall are nonmonotonic and depend jointly on retention interval — related