Interaction between the testing and forward testing effects in the case of Cued-Recall: Implications for Theory, individual difference Studies, and application

Recall from episodic memory has been shown to enhance both memory for the retrieved information (e.g., relative to a restudy control condition; the testing effect, or TE) and memory for different, subsequently studied materials (the forward testing effect, or FTE). Hence, the TE may be subject to an FTE confound when training in a TE experiment involves either testing prior to restudy or when restudied and tested items are randomly mixed. Across two cued-recall TE experiments, we show that (1) a potent FTE confound exists in the test-first but not the mixed training design, (2) there are no other evident learning related interactions between restudied and tested items across three frequently used training phase task orderings, and (3) the predictions of the dual-memory model of test-enhanced learning – which posits that a test trial creates a memory that is separate from the initially encoded study memory, yielding two routes to retrieval for tested items – are held both when there is and is not a confounding FTE. Further, our results yielded no evidence for two accounts of the FTE (the proactive interference and reset of encoding hypotheses) as applied to cued recall but are consistent with two alternative accounts (the strategy change and increasing effort hypotheses). Through distribution analyses we identify a novel and potent FTE individual differences effect that can be accommodated by the latter accounts. Finally, we show that at least three large-n studies exploring individual differences in the TE are confounded by the FTE, compromising conclusions in those papers about the efficacy of the TE across individuals.