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

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.

Decreased Efficiency of Between-Network Dynamics During Early Memory Consolidation With Aging

Aging is associated with memory decline and progressive disabilities in the activities of daily living. These deficits have a significant impact on the quality of life of the aging population and lead to a tremendous burden on societies and health care systems. Understanding the mechanisms underlying aging-related memory decline is likely to inform the development of compensatory strategies promoting independence in old age. Research on aging-related memory decline has mainly focused on encoding and retrieval. However, some findings suggest that memory deficits may at least partly be due to impaired consolidation. To date, it remains elusive whether aging-related memory decline results from defective consolidation. This study examined age effects on consolidation-related neural mechanisms and their susceptibility to interference using functional magnetic resonance imaging data from 13 younger (20–30 years, 8 female) and 16 older (49–75 years, 5 female) healthy participants. fMRI was performed before and during a memory paradigm comprised of encoding, consolidation, and retrieval phases. Consolidation was variously challenged: (1) control (no manipulation), (2) interference (repeated stimulus presentation with interfering information), and (3) reminder condition (repeated presentation without interfering information). We analyzed the fractional amplitude of low-frequency fluctuations (fALFF) to compare brain activity changes from pre- to post-encoding rest. In the control condition, fALFF was decreased in the left supramarginal gyrus, right middle temporal gyrus, and left precuneus but increased in parts of the occipital and inferior temporal cortex. Connectivity analyses between fALFF-derived seeds and network ROIs revealed an aging-related decrease in the efficiency of functional connectivity (FC) within the ventral stream network and between salience, default mode, and central executive networks during consolidation. Moreover, our results indicate increased interference susceptibility in older individuals with dynamics between salience and default mode networks as a neurophysiological correlate. Conclusively, aging-related memory decline is partly caused by inefficient consolidation. Memory consolidation requires a complex interplay between large-scale brain networks, which qualitatively decreases with age.

Restoration of Attention by Rest in a Multitasking World: Theory, Methodology, and Empirical Evidence

In this work, we evaluate the status of both theory and empirical evidence in the field of experimental rest-break research based on a framework that combines mental-chronometry and psychometric-measurement theory. To this end, we (1) provide a taxonomy of rest breaks according to which empirical studies can be classified (e.g., by differentiating between long, short, and micro-rest breaks based on context and temporal properties). Then, we (2) evaluate the theorizing in both the basic and applied fields of research and explain how popular concepts (e.g., ego depletion model, opportunity cost theory, attention restoration theory, action readiness, etc.) relate to each other in contemporary theoretical debates. Here, we highlight differences between all these models in the light of two symbolic categories, termed the resource-based and satiation-based model, including aspects related to the dynamics and the control (strategic or non-strategic) mechanisms at work. Based on a critical assessment of existing methodological and theoretical approaches, we finally (3) provide a set of guidelines for both theory building and future empirical approaches to the experimental study of rest breaks. We conclude that a psychometrically advanced and theoretically focused research of rest and recovery has the potential to finally provide a sound scientific basis to eventually mitigate the adverse effects of ever increasing task demands on performance and well-being in a multitasking world at work and leisure.

A Brief Period of Wakeful Rest after Learning Enhances Verbal Memory in Stroke Survivors

OBJECTIVE

Accumulating evidence suggests that wakeful rest (a period of minimal cognitive stimulation) enhances memory in clinical populations with memory impairment. However, no study has previously examined the efficacy of this technique in stroke survivors, despite the high prevalence of post-stroke memory difficulties. We aimed to investigate whether wakeful rest enhances verbal memory in stroke survivors and healthy controls.

METHOD

Twenty-four stroke survivors and 24 healthy controls were presented with two short stories; one story was followed by a 10-minute period of wakeful rest and the other was followed by a 10-minute visual interference task. A mixed factorial analysis of variance (ANOVA) with pairwise comparisons was used to compare participants' story retention at two time points.

RESULTS

After 15-30 minutes, stroke survivors (p = .002, d = .73), and healthy controls (p = .001, d = .76) retained more information from the story followed by wakeful rest, compared with the story followed by an interference task. While wakeful rest remained the superior condition in healthy controls after 7 days (p = .01, d = .58), the beneficial effect was not maintained in stroke survivors (p = .35, d = .19).

CONCLUSIONS

Wakeful rest is a promising technique, which significantly enhanced verbal memory after 15-30 minutes in both groups; however, no significant benefit of wakeful rest was observed after 7 days in stroke survivors. Preliminary findings suggest that wakeful rest enhances early memory consolidation processes by protecting against the effects of interference after learning in stroke survivors.

Community-based Skill Building Intervention to Enhance Health Literacy Among Older Rural Adults

The purpose of this article is to report the outcomes of a skill building intervention to improve general health literacy and health literacy about complementary and alternative therapies (CAM) among older rural adults. The intervention was implemented in eight rural communities. Descriptive statistics and general linear modeling were used for analysis. A total of 127 older adults completed the initial session and Time 1 questionnaire, 67 (51%) completed the intervention sessions and Time 2 questionnaire, and 52 (40.9%) completed the Time 3 questionnaire five months later. CAM health literacy scores and scores on one general health literacy measure were significantly higher at Time 2 compared to Time 1 and 3. The decline in scores over time suggests a need for continuing strategies to support older adults' health literacy. Assisting older adults to make safe health care choices is a critical role for investigators, nurses, and other health care providers.

No evidence of consolidation of evaluative conditioning during waking rest and sleep

Research on evaluative conditioning (EC) shows that attitudes can emerge from co-occurrences of stimuli, and accumulating evidence suggests that EC usually depends on memory for these stimulus contingencies. Therefore, processes known to aid memory retention may be relevant for the development of stable attitudes. One such process may be memory consolidation, assumed to be promoted by waking rest and sleep. In two pre-registered experiments, we investigated whether waking rest (vs. cognitive activity, Experiment 1) and sleep (vs. wakefulness, Experiment 2) in between conditioning and measurement of EC, consolidate contingency memory and EC. Contrary to our predictions, waking rest (vs. cognitive activity) promoted neither contingency memory nor EC effects. Sleep (vs. wakefulness) decreased forgetting of contingency memory but crucially, it did not attenuate the impact of counterconditioning on contingency memory. Sleep also did not influence EC effects, nor the reduction of EC by counterconditioning. EC effects in both experiments were predicted by contingency memory. Yet, unexpectedly, EC effects occurred in the absence of contingency memory after waking rest, but neither after sleep nor in the active control conditions. Our findings emphasise a role of contingency memory in EC, but it remains unclear whether this role changes during waking rest.

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.