Fig. 2.

Interaction effects on the probability of recall correspond to additive effects on information in memory. The left panel shows data from a hypothetical 2 × 2 experiment with high initial learning and low initial learning in which probability of recall was assessed after a few hours and after 2 days. The effect is interactive, since the high and low learning are associated with a very different delay-driven decrease in recall probability. The middle panel shows how probability of recall could map on to information stored in memory (arbitrary units) according to Pr(recall) = 1 − exp(−(information/50)⁶). The right panel shows that retention interval does not interact with the initial level of learning