Across a broad spectrum of memory tasks, retention is superior following a night of sleep compared to a day of wake. However, this result alone does not clarify whether sleep merely slows the forgetting that would otherwise occur as a result of information processing during wakefulness, or whether sleep actually consolidates memories, protecting them from subsequent retroactive interference. Two influential studies suggested that sleep protects memories against the subsequent retroactive interference that occurs when participants learn new yet overlapping information (interference learning). In these studies, interference learning was much less detrimental to memory following a night of sleep compared to a day of wakefulness, an indication that sleep supports this important aspect of memory consolidation. In the current replication study, we repeated the protocol of and, additionally, we examined the impact of intrinsic motivation on performance in sleep and wake participants. We were unable to replicate the finding that sleep protects memories against retroactive interference, with the detrimental effects of interference learning being essentially the same in wake and sleep participants. We also found that while intrinsic motivation benefitted task acquisition it was not a modulator of sleep-wake differences in memory processing. Although we cannot accept the null hypothesis that sleep has no role to play in reducing the negative impact of interference, the findings draw into question prior evidence for sleep's role in protecting memories against interference. Moreover, the current study highlights the importance of replicating key findings in the study of sleep's impact on memory processing before drawing strong conclusions that set the direction of future research.

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Across a broad spectrum of memory tasks, retention is superior following a night of sleep compared to a day of wake. However, this result alone does not clarify whether sleep merely slows the forgetting that would otherwise occur as a result of information processing during wakefulness, or whether sleep actually consolidates memories, protecting them from subsequent retroactive interference.Two influential studies (Ellenbogen, et al., , 2009 suggested that sleep protects memories against the subsequent retroactive interference that occurs when participants learn new yet overlapping information (interference learning). In these studies, interference was much less detrimental to memory following a night of sleep compared to a day of wakefulness, a finding that provided strong evidence that sleep supports this important aspect of memory consolidation. In the current well-powered replication study, we repeated the protocol of Ellenbogen, et al. (2009) and, additionally, we examined the impact of intrinsic motivation on performance in sleep and wake participants. We were unable to replicate the finding that sleep protects memories against retroactive interference, with the detrimental effects of interference learning being essentially the same in wake and sleep participants. We also found that while intrinsic motivation benefitted task acquisition it was not a modulator of sleep-wake differences in memory processing. These finding of this replication study draw into question the claim that sleep protects memories against the effects of retroactive interference, and moreover, they highlight the importance of replicating key findings in the study of sleep's impact on memory processing before drawing strong conclusions that drive the direction of future research.

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This article was migrated. The article was marked as recommended. Introduction Medical students are tasked with learning a vast amount of medical knowledge prior to sitting for the USMLE Step 1 exam, a portion of which is either forgotten or becomes inaccessible to memory following each exam. In this study we examined whether accessibility and retention of 1 st -year biochemistry content predicts performance on high stakes exams such as USMLE Step1. Methods First-year medical students were retested on a subset of biochemistry final exam items 10.5 months after sitting for the original exam. Retention was measured as a percentage of the original final exam score. Availability of information was measured with cued recall (i.e., selecting from a list the multiple-choice distractors), while accessibility of information was captured through free recall (without the aid of multiple choice distractors). Results As expected, we found that free recall rates were much lower than cued recall rates, but that students who scored higher on Step 1 had a smaller gap between cued and free recall scores, demonstrating a greater ability to access information than lower-scoring students. Importantly, we also demonstrate that higher-scoring students retained a higher percentage of the original biochemistry material than lower-performing students after 10.5 months, and that the amount information retained in memory was associated with higher scores on Step 1, demonstrating the potential importance of teaching medical school content with the intention of making it stick , especially in students who are not as strong academically. Conclusion The methods employed in this study are straightforward and can be used to compare retention and accessibility of information across medical school courses, and may serve as a guide to curriculum and pedagogical improvements.