Recent research on cognitive control has focused on the learning consequences of high selective attention demands in selective attention tasks (e.g., Botvinick, 2007;. The current study extends these ideas by examining the influence of selective attention demands on remembering. In Experiment 1, participants read aloud the red word in a pair of red and green spatially interleaved words. Half of the items were congruent (the interleaved words had the same identity), and the other half were incongruent (the interleaved words had different identities). Following the naming phase, participants completed a surprise recognition memory test. In this test phase, recognition memory was better for incongruent than for congruent items. In Experiment 2, context was only partially reinstated at test, and again recognition memory was better for incongruent than for congruent items. In Experiment 3, all of the items contained two different words, but in one condition the words were presented close together and interleaved, while in the other condition the two words were spatially separated.Recognition memory was better for the interleaved than for the separated items. This result rules out an interpretation of the congruency effects on recognition in Experiments 1 and 2 that hinges on stronger relational encoding for items that have two different words. Together, the results support the view that selective attention demands for incongruent items lead to encoding that improves recognition.3

Recent research in the area of desirable difficulty--defined as processing difficulty at either encoding or retrieval that improves long-term retention--has demonstrated that perceptually blurring an item makes processing less fluent, but does not improve remembering (Yue et al., 2013). This result led us to examine more closely perceptual blurring as a potential desirable difficulty. In Experiment 1, better recognition of blurry than clear words was observed, a result that contrasts with those reported by Yue et al. This result was replicated in Experiment 2, in which both mixed-list and pure-list designs were used. The following experiments were conducted to determine when blurring does and does not result in enhanced remembering. The desirable difficulty effect observed in Experiments 1 and 2 was replicated in Experiments 3A, 3B, and 3C, despite varying encoding intent during study, context reinstatement at the time of test, study list length, and the nature of the distractor task between study and test phases. It was only in Experiments 4A and 4B that a null effect of perceptual blurring on remembering was found. These experiments demonstrated that (1) the level of blurring used is critical, with a lower blurring level producing results similar to Yue et al. (2013), and (2) the introduction of judgments of learning at the time of study eliminated the benefit of blurring on remembering. These results extend the desirable difficulty principle to encoding manipulations involving perceptual blurring, and identify judgments of learning at encoding as a powerful moderator of this particular desirable difficulty effect.

The present study examines the effect of immediate repetition on recognition memory. In a series of 4 experiments, the study phase task was to name aloud a word that was immediately preceded by either the same word (repeated trials) or a different word (not-repeated trials). Across experiments, performance in the study phase demonstrated the anticipated benefit in naming times for repeated trials. More important, performance in the test phase revealed greater sensitivity for not-repeated than repeated trials. This effect was observed even when repetitions at study were separated by an unrelated word (Experiment 3), and was eliminated only when participants named both words in succession at study (Experiment 4). These findings fit nicely with the desirable difficulty principle (R. A. Bjork, 1994), as they demonstrate that items more easily processed at study (i.e., repeated items) are not as well-encoded as items that are more difficult to process at study (i.e., not-repeated items). Furthermore, the current study points to the possibility that attentional orienting in response to processing difficulty may constitute a broadly important cognitive control adaptation that impacts memory encoding.

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