Retrieval-induced forgetting: Dynamic effects between retrieval and restudy trials when practice is mixed

Abstract

Results from numerous previous studies suggest that when subjects study items from different categories and then repeatedly retrieve, or restudy, some of the items from some of the categories, repeated retrieval, but not repeated study, induces forgetting of related unpracticed items. We investigated in two experiments whether such effects of pure retrieval and pure study practice generalize to mixed practice-that is, when retrieval and restudy trials are randomly interleaved within a single experimental block. Experiment 1 employed cued recall; Experiment 2 employed item recognition testing. In both experiments, pure repeated retrieval, but not pure repeated study, caused forgetting of related unpracticed items, which is consistent with the prior work. In contrast, with mixed practice, both retrieval and restudy induced forgetting. Thus, whereas retrieval caused forgetting regardless of practice mode, restudy caused forgetting with mixed practice, but not with pure practice. The finding provides first evidence for dynamic effects between retrieval and restudy trials when practice is mixed. It is consistent with the view that, with mixed practice, subjects engage in more retrieval during restudy trials, so that restudy trials may trigger similar processes as retrieval trials and, thus, induce forgetting of related, not restudied, items.

Comparing the testing effect under blocked and mixed practice: The mnemonic benefits of retrieval practice are not affected by practice format

“…This result indicates that the prior findings and conclusions by Dobler and Bäuml (2013) may not generalize to the testing effect; the testing effect, in contrast to retrievalinduced forgetting, does not seem to be affected by practice format. In particular, the fact that the testing effect was not sensitive to practice format under standard experimental procedures used to study the effect and that it occurred after both short (5-min) and long (7-day) retention intervals indicates that retrieval-practice effects are robust across these manipulations; in particular, the findings show that the testing effect is unaffected by practice format, irrespective of whether the final test is relatively easy (after short delay) or relatively difficult (after prolonged delay).…”

“…In Experiment 2, subjects studied unrelated word pairs, engaged repeatedly in either blocked or mixed practice, and completed a final test in the presence or absence of retroactive interference, which constitutes another way of manipulating difficulty at test. Our experiments will show whether Dobler and Bäuml's (2013) findings on retrieval-induced forgetting generalize to the testing effect by examining whether study trials have greater impact (thus reducing the testing effect) during random than during blocked practice. That is, mixed practice should reduce the testing effect, because random switches between practice types might encourage subjects to keep engaging in retrieval practice during restudy trials.…”

“…A recent study by Dobler and Bäuml (2013) was the first to address whether practice format was of relevance for retrieval-induced forgetting. Their results showed that when practice was blocked and retrievalpractice and restudy trials were clearly separated, only selective retrieval practice (but not restudy) led to retrieval-induced forgetting (thus replicating prior work; e.g., Hanslmayr et al, 2010).…”

“…Thus, mixed practice is unlikely to affect the testing effect in the same Ball-or-none^way as it appears to do in retrieval-induced forgetting research; it remains unclear, though, whether practice format is relevant for the size of the testing effect. Dobler and Bäuml (2013) suggested that, during mixed practice, subjects might keep engaging in retrieval practice when switching from the harder (retrieval-practice) trials to the easier (restudy) trials. However, this particular type of switching might only occur for a part of the to-be-restudied materials (perhaps later in practice), so that differences between blocked and mixed practice might be more subtle with regard to the benefits of retrieval practice.…”

“…On the basis of the results reported by Dobler and Bäuml (2013), a contrasting prediction on the role of practice format (blocked vs. randomly intermixed) for the testing effect arises under more standard conditions used in testing-effect studies. In particular, we predicted from their work that typical testing effects would be larger with blocked than with mixed practice lists, because in the latter case subjects would covertly retrieve on the restudy trials.…”