Effects of Testing and Enactment on Memory

Abstract: Learning occurs not only when we encode information but also when we test our memory for this information at a later time. In three empirical studies, I investigated the individual and combined effects of interleaved testing (via repeated rounds of study and test practice) and encoding (via motor enactment) during learning on later cued-recall performance for action phrases. Such materials (e.g., “water the flowers”) contain a verb and a noun and approximate everyday memory that typically revolves around past and future actions. Study I demonstrated that both interleaved testing (vs. study only) and enactment (vs. verbal encoding) individually reduced the forgetting rate over a period of 1 week, but these effects were nonadditive. That is, the direct testing effect on the forgetting rate occurred for verbal, but not for enactive encoding; enactment reduced the forgetting rate for the study-only condition, but not for the study–test condition. A possible explanation of these findings is that both study techniques sufficiently elicit verb–noun relational processing that cannot be increased further by combining them. In Studies II and III, I replicated these testing-effect results and investigated whether they varied as a function of recall type (i.e., noun-cued recall of verbs and verb-cued recall of nouns). For verbal encoding (Study II), the direct testing effect was of similar size for both noun- and verb-cued recall. For enactive encoding, the direct testing effect was lacking irrespective of recall type. In addition, interleaved tests enhanced subsequent re-encoding of action phrases, leading to an accelerated learning. This indirect testing effect was increased for the noun-cued recall of verbs—for both verbal and enactive encoding. A possible explanation is that because nouns are semantically more stable, in that the meaning of nouns changes less over time and across different contexts, they are more recognizable. Hence, associated information (e.g., about the recall status) may be more available to the learner during restudy that, in turn, can initiate more effective re-encoding. The two different testing benefits (i.e., direct and indirect) may, partly, engage different mechanisms, as they were influenced differentially by the manipulations of encoding type and recall type. The findings presented in the thesis provide new knowledge regarding the combined effects of strategies and materials that influence memory.