The origin of the interaction between learning method and delay in the testing effect: the roles of processing and conceptual retrieval organization.

Recent research has demonstrated a relationship between retrieval organization and the efficacy of prior repeated retrieval on delayed tests. The present study asked why repeated study engenders higher recall at a short delay despite lower retrieval organization but produces a decline at a long delay, and why repeated retrieval engenders lower recall at a short delay despite higher retrieval organization but produces stable recall over time. This relationship was examined through the inclusion of two successive recall tests-one immediately after learning method and one a week later. Results replicated the interaction in recall between learning method and delay characterizing the testing effect and, critically, revealed the qualitative differences inherent in the retrieval organization of each method. Specifically, stable recall in repeated retrieval was accompanied by strong and sustained conceptual organization, whereas organization for repeated study was tenuous and weakened across tests. These differences quantitatively were assessed through the use of five targeted analyses: specifically, the examination of cumulative recall curves, the accumulation of organization across time (a curve akin to cumulative recall), item gains and losses across time, changes in the size of categories across time, and the fate of specific clusters of recalled items across time. These differences are discussed within the context of differential processes occurring during learning method.