Does Sleep Protect Memories Against Interference? A Failure to Replicate

Abstract

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.