Evidence against a large effect of sleep in protecting verbal memories from interference

Abstract

A fundamental question in memory research is how the brain establishes stable memories while remaining plastic enough to update entries flexibly and to integrate novel information into existing networks. How can the brain protect old memories from forgetting or being overwritten by new learning (French, 1999)? Research on memory stability and plasticity has been a key topic in psychology and neuroscience for more than a century (Lechner, Squire, & Byrne, 1999). At the end of the 19th century, Müller and Pilzecker (1900) realized that memories have to undergo a maturation process to become long-lasting and stable. They noticed that conflicting information intervening between the presentation and recall of word pairs disrupted memory for the to-be-remembered items, and named this phenomenon retroactive interference. Müller and Pilzecker reasoned that a time-dependent and learning-related physiological mechanism must be responsible for the transformation of the labile memory trace into an enduring state, because the vulnerability of a memory trace depended on its age. They termed the process that stabilized memories while increasing their resistance to interference consolidation, and assumed that the progress in memory consolidation can be approximated by how resistant new memories were against interfering information. Around the same time, it emerged that sleep supported the formation of memories. Hermann Ebbinghaus noticed that humans forget less over periods of sleep as compared with wakefulness (Ebbinghaus, 1885). Later experiments found that verbal material was more likely to be remembered when it was learnt shortly

Does sleep-dependent consolidation favour weak memories?

“…This approach has been taken in a series of studies explicitly testing the protective effect of sleep against retroactive interference. Indeed, despite training participants to 100% pre-delay memory accuracy, the introduction of retroactive interference after the delay and before the final retrieval revealed a beneficial effect of sleep over wake, i.e., a sleep-dependent consolidation effect ( Ellenbogen, Hulbert, Jiang, & Stickgold, 2009 ; Ellenbogen et al., 2006 ; but see; Bailes, Caldwell, Wamsley, & Tucker, 2020 ; Pöhlchen, Pawlizki, Gais, & Schönauer, 2020 ). In line with these studies, we used retroactive interference to increase retrieval difficulty and thereby push memory performance from ceiling.…”

Understanding relational binding in early childhood: Interacting effects of overlap and delay

“…Relatively little is known about how young children's episodic memory performance changes when tested immediately or after a delay of 24 hours or more. In adults, a delay period filled with sleep as compared to an equivalent delay filled with wakefulness may protect against memory interference (Abel & Bäuml, 2014;Ellenbogen, Hulbert, Stickgold, Dinges, & Thompson-Schill, 2006;Sheth, Varghese, & Truong, 2012;Spencer, Sunm, & Ivry, 2006; but see also Bailes, Caldwell, Wamsley, & Tucker;Pöhlchen, Pawlizki, Gais, Schönauer;, likely due to sleep-related consolidation. Designs with delays up to 24 hours demonstrate that increases in the length of the delay between encoding and test increase forgetting (Payne et al, 2012;Takashima et al, 2009), but this decline is attenuated by sleep during the delay, especially if it directly follows learning (Payne et al, 2012).…”

Does sleep-dependent consolidation favour weak memories?

“…Indeed, despite training participants to 100% pre-delay memory accuracy, the introduction of retroactive interference after the delay and before the final retrieval revealed a beneficial effect of sleep over wake, i.e. a sleep-dependent consolidation effect (Ellenbogen, Hulbert, Jiang, & Stickgold, 2009;Ellenbogen et al, 2006; but see Bailes, Caldwell, Wamsley, & Tucker, 2020;Pöhlchen, Pawlizki, Gais, & Schönauer, 2020). That said, these studies did not compare the impact of retroactive interference on sleep-dependent consolidation effects for memories initially strong vs. weak, leaving open whether sleep protects all memories against retroactive interference.…”