Post-encoding wakeful resting supports the retention of new verbal memories in children aged 13-14 years

Post-encoding task engagement not attentional load is detrimental to awake consolidation

The fate of new memories depends partly on the cognitive state experienced immediately following encoding. Wakeful rest, relative to task engagement, benefits retention and this effect is typically explained through a consolidation account: rest is theorised to provide a state of minimal interference, which would otherwise disrupt consolidation. Yet, the determinants of consolidation interference, notably the contribution of attention, remain poorly characterised. Through a repeated measures design, we investigated attention load's impact on consolidation. In three phases, participants encountered a set of nonwords and underwent immediate recognition testing, experienced a 5-min delay condition, and completed a delayed recognition test for the nonwords. This cycle repeated for each phase before proceeding to the next. Delay conditions comprised of wakeful rest and two sustained attention to response tasks (SART) that were of low (SART-fixed) and high (SART-random) attention load. Immediate memory was matched across conditions, but delayed recognition was poorer after completing the SART-fixed and SART-random conditions, relative to rest. There was no difference between the two SART conditions. These data provide insights into the factors that contribute to the success of consolidation and indicate that the attention load of a task does not determine the magnitude of consolidation interference and associated forgetting.

An online experiment that presents challenges for translating rest-related gains in visual detail memory from the laboratory to naturalistic settings

New memories are labile and consolidate over time. Contemporary findings demonstrate that, like sleep, awake quiescence supports consolidation: people remember more new memories if they experience a brief period of post-encoding quiet rest than sensory processing. Furthermore, it was recently demonstrated that the quality of new memories can also be enhanced significantly by awake quiescence. This phenomenon offers great applied potential, for example, in education and eyewitness testimony settings. However, the translation of rest-related gains from the laboratory to everyday life remains poorly characterised and findings are mixed. Here, we report follow-on evidence demonstrating that rest-related gains in visual detail memory may be more challenging to achieve in naturalistic than laboratory-based settings. In contrast to established laboratory findings, using an online version of an established consolidation paradigm, we observed no memory benefit of post-encoding quiescence, relative to an engaging perceptual task, in the retention of detailed visual memories as measured through a lure discrimination task. This null finding could not be explained by intentional rehearsal in those who rested or between-group differences in participants' demographics or mental state, including fatigue and mood. Crucially, post-experimental reports indicated that those in the rest group experienced challenges in initiating and maintaining a state of quiescence, which may account for our null finding. Based on these findings, we propose three areas of focus for future work should rest-related gains in memory be translated from the lab to field: (1) to establish the specific environmental and individual conditions that are conducive and detrimental to awake consolidation, (2) to understand the barriers to initiating and maintaining a state of quiescence in naturalistic settings, and (3) to examine how knowledge of quiescence and its cognitive benefits can encourage the initiation and maintenance of states that are conductive to awake consolidation.

Individual differences in sensory processing sensitivity amplify effects of post-learning activity for better and for worse

Sensory processing sensitivity (SPS) is a biologically-based trait associated with greater reactivity to both positive and negative environments. Recent studies suggest that the activity following learning can support or hinder memory retention. Here, we employed a within-subject experiment to examine whether and how individual differences in SPS contribute to differences in memory retention. Sixty-four participants encoded and immediately recalled two word lists: one followed by 8-min of eyes-closed, wakeful resting; and the other by a distraction task. After 7 days, participants completed a surprise free recall test for both word lists. If participants wakefully rested after encoding, memory retention increased as a function of higher SPS. However, in the distraction condition, a negative curvilinear relationship indicated that memory retention was especially hindered for highly sensitive individuals. These results suggest that individual differences in SPS are an important factor to consider when examining the effects of environmental conditions on learning and memory.

Wakeful resting and listening to music contrast their effects on verbal long-term memory in dependence on word concreteness

Wakeful resting and listening to music are powerful means to modulate memory. How these activities affect memory when directly compared has not been tested so far. In two experiments, participants encoded and immediately recalled two word lists followed by either 6 min wakefully resting or 6 min listening to music. The results of Experiment 1 show that both post-encoding conditions have a similar effect on memory after 1 day. In Experiment 2, we explored the possibility that less concrete words, i.e. lower in imageability than in Experiment 1, are differently affected by the two post-encoding conditions. The results of Experiment 2 show that, when words are less concrete, more words are retained after 1 day when encoding is followed by wakeful resting rather than listening to music. These findings indicate that the effects of wakeful resting and listening to music on memory consolidation are moderated by the concreteness of the encoded material.

'Sleep-dependent' memory consolidation? Brief periods of post-training rest and sleep provide an equivalent benefit for both declarative and procedural memory

Sleep following learning facilitates the consolidation of memories. This effect has often been attributed to sleep-specific factors, such as the presence of sleep spindles or slow waves in the electroencephalogram (EEG). However, recent studies suggest that simply resting quietly while awake could confer a similar memory benefit. In the current study, we examined the effects of sleep, quiet rest, and active wakefulness on the consolidation of declarative and procedural memory. We hypothesized that sleep and eyes-closed quiet rest would both benefit memory compared with a period of active wakefulness. After completing a declarative and a procedural memory task, participants began a 30-min retention period with PSG (polysomnographic) monitoring, in which they either slept (n = 24), quietly rested with their eyes closed (n = 22), or completed a distractor task (n = 29). Following the retention period, participants were again tested on their memory for the two learning tasks. As hypothesized, sleep and quiet rest both led to better performance on the declarative and procedural memory tasks than did the distractor task. Moreover, the performance advantages conferred by rest were indistinguishable from those of sleep. These data suggest that neurobiology specific to sleep might not be necessary to induce the consolidation of memory, at least across very short retention intervals. Instead, offline memory consolidation may function opportunistically, occurring during either sleep or stimulus-free rest, provided a favorable neurobiological milieu and sufficient reduction of new encoding.

Individual differences in working memory capacity moderate effects of post-learning activity on memory consolidation over the long term

Similar to sleeping after learning, a brief period of wakeful resting after encoding new information supports memory retention in contrast to task-related cognition. Recent evidence suggests that working memory capacity (WMC) is related to sleep-dependent declarative memory consolidation. We tested whether WMC moderates the effect of a brief period of wakeful resting compared to performing a distractor task subsequent to encoding a word list. Participants encoded and immediately recalled a word list followed by either an 8 min wakeful resting period (eyes closed, relaxed) or by performing an adapted version of the d2 test of attention for 8 min. At the end of the experimental session (after 12–24 min) and again, after 7 days, participants were required to complete a surprise free recall test of both word lists. Our results show that interindividual differences in WMC are a central moderating factor for the effect of post-learning activity on memory retention. The difference in word retention between a brief period of wakeful resting versus performing a selective attention task subsequent to encoding increased in higher WMC individuals over a retention interval of 12–24 min, as well as over 7 days. This effect was reversed in lower WMC individuals. Our results extend findings showing that WMC seems not only to moderate sleep-related but also wakeful resting-related memory consolidation.

Resting States and Memory Consolidation: A Preregistered Replication and Meta-Analysis

While several recent studies have found that a post-encoding period of quiet, eyes-closed waking rest benefits memory consolidation, others have reported null effects. To more precisely estimate this effect, we conducted a quasi-exact behavioural replication of a recent study from our lab, which found that post-training eyes-closed waking rest improved declarative memory relative to a distractor task. Contrary to our hypothesis, the observed effect was not significant; however, it did fall within the 95% confidence interval of our previous finding. Furthermore, a meta-analytic effect summarizing n = 10 similar studies indicates a moderately sized and significant benefit of waking rest for verbal memory (d = 0.38, p < 0.001). We argue that the apparently conflicting results in this literature are most parsimoniously explained by variability due to sampling and/or measurement error, in a group of studies often underpowered to detect a smaller-than-expected effect of rest. Additionally, exploratory analyses revealed that increased trait daydreaming frequency negatively correlated with memory retention during eyes-closed rest. Together with our replication and meta-analysis, these studies suggest that waking rest confers a small but significant benefit on memory consolidation, and that this benefit requires the mind to be free from attention to either external tasks or spontaneous thought.

Factors modulating the effects of waking rest on memory

Study results indicate that moments of unoccupied rest immediately after learning serve an essential cognitive function: memory consolidation. However, there also are findings suggesting that waking rest after learning has similar effects on delayed memory performance as an active wake condition, where participants work on a cognitive distractor task. Based on these studies, we highlight several potentially modulating factors of the so-called resting effect.

Brief period of post-encoding wakeful rest supports verbal memory retention in children aged 10–13 years

Evidence exists that a brief period of wakeful rest after learning can support the retention of memories, whereas a period filled with a cognitive task after learning can weaken the retention of memories. The present study in 10–13 year old children investigated whether wakeful resting after encoding is more beneficial for the retention of new verbal information than watching movies, which reflects a common everyday life/learning break activity in children at this age. Children encoded a word list. After immediate recall of this word list, they wakefully rested for 12 min. Next, children encoded another word list. After immediate recall of this word list, they watched animated short movies for 12 min. The order of the delay conditions (rest, movies) was counterbalanced across children. At the end of the experimental session, a surprise free recall test took place. Overall analyses revealed that while memory performance decreased over time in both the resting condition and movies condition, it decreased significantly more in the movies condition. These results indicate that wakeful resting supports the retention of verbal information in children aged 10–13 years.

Wakeful resting and memory retention: a study with healthy older and younger adults

Studies indicate that a brief period of wakeful rest after learning supports memory retention, whereas distraction weakens it. It is open for investigation whether advanced age has a significant effect on the impact of post-learning wakeful rest on memory retention for verbal information when compared to a cognitively demanding distraction task. In this study, we examined (1) whether post-learning rest promotes verbal memory retention in younger and older adults and (2) whether the magnitude of the rest benefit changes with increasing age. Younger adults and older adults learned and immediately recalled two consecutive word lists. After one word list, participants rested wakefully for 8 min; after the other list, they solved matrices. Memory performance was again tested in a surprise free recall test at the end of the experimental session. We found that, overall, younger adults outperformed older adults. Also, memory retention was higher following a wakeful rest phase compared to distraction. A detailed analysis revealed that this wakeful rest benefit was significant for the older adults group, whereas the younger adults group retained a similar amount of information in both post-encoding conditions. We assume that older adults can profit more from a wakeful rest phase after learning and are more prone to distraction than younger adults. With increasing age, a short break immediately after information uptake may help better retain the previously learned information, while distraction after learning tends to weaken memory retention.