Do we remember when to better recall what? Repetition benefits are probably not due to explicit temporal context memory

A number of temporal context-based theories of the spacing effect assume that temporal context is retrieved during repetitions, allowing better memory on a later test. Since associations in memory are often bidirectional, if we can use temporal context to recall an item, perhaps we can also use the item to explicitly recall its temporal context. If so, explicit memory-for-when during study would be a good predictor of later recall for repeated items. Experiment 1 appeared to be consistent with our predictions; items with memory-for-when during List 2 showed superior recall accuracy on a final free recall test. However, the effect was primarily driven by better memory-for-when in the primacy region. Experiment 2 used an incidental learning procedure during List 1 to reduce this confound since the primacy region is greatly attenuated in incidental learning. While the benefits of having memory-for-when persisted in Experiment 2, they were again attributable solely to the first few items on the list. The results suggest that explicit temporal context information is unlikely to underlie the benefits of spaced repetition. Either temporal context information is strengthened implicitly, our measures of context failed to capture the type of context used in spacing, or other mechanisms entirely produce the benefits of repetition.