Practice and Retention

Practice and Retention: A Unifying Analysis

John R. Anderson Jon Fincham

Abstract

What is the strength of a memory trace which has received various practices at times t_j in the past? The Strength Accumulation Equation proposes Strength =

t_j^-d where the summation is over the practices of the trace. This equation predicts both the power law of practice and the power law of retention. This paper reports the fits of the predictions to five experiments derived from the Strength Accumulation Equation. Across these experiments, participants receive as many as 200 trials of practice distributed over intervals as long as 400 days. The experiments also vary whether participants are just practicing retrieving an item or practicing applying a relatively complex rule. A model based on this equation successfully fits all the data if we assume slowed passage of psychological time after the experimental session. The Strength Accumulation Equation is compared to other conceptions of the retention function and the relationship of the retention function to the practice function.