Neural mechanisms of the spacing effect in episodic memory: A parallel EEG and fMRI study

Enhancing cosmetic suturing skill acquisition in surgical residents through spaced learning training: a randomized controlled trial

BACKGROUND

Previous research has strongly supported the utility of spaced learning in enhancing memory, but its effectiveness in complex surgical procedures has largely been unexplored. The main objective of this study was to evaluate whether, in comparison to concentrated learning, spaced learning improves the short-term acquisition and long-term retention of cosmetic suturing skills as outcomes of surgical resident training courses.

METHODS

This randomized controlled trial was conducted from February 2023 to June 2023. Surgical residents were recruited from a teaching hospital in Guangzhou, China. The participants were randomly assigned at a 1:1 ratio to either the spaced training group (40 min of training followed by a 20-minute break) or the concentrated training group (3 h of continuous training), in which they received one-on-one training for cosmetic suturing skills. The short-term acquisition and long-term retention outcomes were evaluated by three independent raters using an objective scoring scale to assess the participants' cosmetic suturing skills before the training (pretraining test), within one hour after the training (posttraining test), and three months after the completion of the training (follow-up test). The score for each participant was calculated as the average of three independent scores.

RESULTS

The study included 23 surgical residents, 12 in the spaced training group and 11 in the concentrated training group. The pretraining test revealed no significant difference between the groups. However, in the post-training test, the spaced training group achieved a significantly higher total score than did the concentrated training group (74.06 ± 5.87 vs. 63.43 ± 10.73, p = 0.0070). Specifically, the suture technique scores were 28.46 ± 1.78 and 22.85 ± 3.75, respectively, which were significantly different (p = 0.0002). During the long-term follow-up test, the spaced training group consistently outperformed the concentrated training group by having significantly higher total (75.60 ± 4.78 vs. 60.68 ± 10.40, p = 0.0001), suture quality (32.26 ± 4.01 vs. 26.23 ± 4.16, p = 0.0019), suture technique (28.68 ± 2.63 vs. 22.18 ± 3.94, p = 0.0001), and suturing time scores (14.67 ± 1.15 vs. 12.27 ± 6.07, p = 0.0460).

CONCLUSIONS

Incorporating the principles of spaced learning into the instructional process of obtaining cosmetic suture skills for surgical residents not only significantly enhances short-term skill improvement but also contributes to the long-term retention of training outcomes.

Does the reactivity effect of judgments of learning transfer to learning of new information?

ABSTRACTMaking judgments of learning (JOLs) can reactively change memory, a phenomenon termed the reactivity effect. The current study was designed to explore whether the reactivity effect transfers to subsequent learning of new information. Participants studied two blocks of words (Experiment 1) or related word pairs (Experiments 2 & 3). In Block 1, participants in the experimental (JOL) group made a JOL while studying each item, whereas the control (no-JOL) group did not make item-by-item JOLs. Then both groups studied Block 2, in which they did not make JOLs, and finally, they took a test on Blocks 1 and 2. Across Experiments 1 -3, the results showed superior Block 1 test performance in the JOL than in the no-JOL group, demonstrating a positive reactivity effect. Critically, there was minimal difference in Block 2 test performance between the two groups, implying little transfer of the positive reactivity effect to subsequent learning of new information. Furthermore, Experiment 3 demonstrated that the reactivity effect still failed to transfer even when participants explicitly appreciated the benefits of making JOLs. Educational implications are discussed.

Negative recency effects in delayed recognition: Spacing, consolidation, and retrieval strategy processes

While items learned immediately before testing are generally remembered better than prior items in a study list, in delayed testing this relationship is reversed, yielding a negative recency effect. To adjudicate between the strategic rehearsal and spacing accounts of this phenomenon, we examined performance of 169 participants on a delayed recognition test following multiple sessions requiring the study and immediate free recall testing of 16 lists of 16 words. This revealed a strong effect of the amount of spacing between initial study position and initial free recall position on the degree of negative recency, supporting the spacing account. Furthermore, these spacing effects were nonmonotonic, suggesting that they are mediated by consolidation processes. Additional analyses indicate that strategies and rehearsal opportunities may also contribute to the effects of within-list encoding position on subsequent long-term memory, but for recall more than for recognition.

Science of Learning Strategy Series: Article 3, Interleaving

Interleaving is an evidence-based, learning-science strategy that is relevant to the planning and implementation of continuing professional development (CPD). Mixing related but different areas of study forces the brain to reconcile the relationship between the areas while understanding each area well. By doing so, interleaving increases the likelihood of mastery and memory. Research from cognitive psychology and neuroscience provides the rationale for interleaving, and examples of its implementation in health profession education have begun to appear in the literature. If utilized appropriately, some common CPD interventions can leverage interleaving. Through increased understanding, CPD participants can benefit from interleaving by making more-informed educational choices, and CPD planners can benefit in efforts to improve educational activities.

Evidence of the Spacing Effect and Influences on Perceptions of Learning and Science Curricula

The conventional science curricula generally favour educational practices that yield high scores on immediate examination, though it may not accurately predict students’ long-term academic achievement. In view of the pre-exam cramming phenomenon, this article shows the evidence of spacing effect in science education and probes into its theoretical mechanisms, effectiveness in experimental settings, and current applications in science learning. In brief, spacing works by repeatedly presenting the learning material across various temporal intervals. This paper suggests that spacing could significantly result in greater memory strength by alleviating multiple neurocognitive and behavioural properties of learning that are hampered by cramming. Together with the analysis of its relevance in science education, the spacing effect may further provide leverages for promoting long-term conceptual understanding and reflective skill development. However, there are many reasons that students and teachers may not be aware of or fully appreciate its benefits. Finally, this article discusses systemic barriers to why spaced repetition is underutilized in science curricula.

The contributions of the left fusiform subregions to successful encoding of novel words

The left fusiform cortex has been identified as a crucial structure in visual word learning and memory. Nevertheless, the specific roles of the fusiform subregions in word memory and their consistency across different writings have not been elaborated. To address these questions, the present study performed two experiments, in which study-test paradigm was used. Participants' brain activity was measured with fMRI while memorizing novel logographic words in Experiment 1 and novel alphabetic words in Experiment 2. A post-scan recognition memory test was then administered to acquire the memory performance. Results showed that, neural responses in the left anterior and middle fusiform subregions during encoding were positively correlated with recognition memory of novel words. Moreover, the positive brain-behavior correlations in the left anterior and middle fusiform cortex were evident for both logographic and alphabetic writings. The present findings clarify the relationship between the left fusiform subregions and novel word memory.

Game-based brain training for improving cognitive function in community-dwelling older adults: A systematic review and meta-regression

BACKGROUND

Given that increasing aging is associated with a natural decline in cognitive function, identifying effective interventions that can help to prevent cognitive decline in older adults is a research priority.

OBJECTIVE

To synthesize the best evidence to assess the effectiveness of game-based brain training in improving cognitive function and to evaluate the preferred design features of the intervention.

METHODS

Twelve databases, trial registries, and gray literature resources were systematically searched for in randomized controlled trials. Meta-analysis and random-effects meta-regression were conducted using Comprehensive Meta-analysis Software 3.0. Overall effect was measured using Hedges's g and determined using Z-statistics. Cochran's Q test and I2 were used to investigate heterogeneity. The Grading of Recommendation, Assessment, Development, and Evaluation system was used to assess overall quality of evidence.

RESULTS

Fifteen trials among 759 older adults were conducted. Meta-analysis revealed that game-based brain training significantly improved processing speed (g = 0.23), selective attention (g = 0.40), and short-term memory (g = 0.35) versus a control group. Our subgroup analyses emphasized that non-time pressure games, multiplayer, computer platform, provider support, sessions ≤ 3 times per week for ≤ 60 min. each comprised a preferable design. Meta-regression identified game design (β = 0.211, p = 0.008) that had statistically significant effects on processing speed. Egger's regression asymmetry test (p = 0.293) suggested no publication bias.

CONCLUSIONS

Game-based brain training can be considered a supplementary intervention for improving cognitive functions in community-dwelling older adults. Future trials should use well-designed trials with large sample sizes.

Specifying the neural basis of the spacing effect with multivariate ERP

The spacing effect refers to the finding that, given a fixed amount of study time, a longer interval between study repetitions improves long-term retention (e.g., Cepeda et al., 2006; Ebbinghaus, 1885/1967; Melton, 1970). Although the spacing effect is a robust and reliable finding in the memory literature, its cognitive and neural mechanisms remain unclear. We used event-related potentials (ERPs) to investigate the neural correlates of the spacing effect in the context of the study-phase retrieval hypothesis, which posits that repeated exposure of an item serves as a reminder of one's previous experience with the item, thereby promoting long-term retention. ERPs were recorded from 30 healthy young adults as they studied pairs of words under three levels of lag, corresponding to 0, 4, or 12 intervening pairs between the first and second occurrences of a target pair. We used two study-phase tasks that differed in the degree of retrieval that was required. During the test phase, participants were tested on paired-associate recall. The results demonstrated a significant effect of spacing on memory performance. However, the effect of encoding task and the interaction between encoding task and spacing were not significant. The results of the partial least squares analyses, which are not constrained by time window or electrode selection, revealed a spacing effect on the ERP data for both study-phase tasks; this effect occurred late in the epoch and was most salient over the centro-parietal scalp region. The results add to the literature on the neural correlates of the spacing effect by providing a more comprehensive account compared to past ERP findings that were focused on testing specific ERP components. They also call for further investigation on the various theoretical accounts of the spacing effect.

Role of the hippocampus in the spacing effect during memory retrieval

It is well known that distributed learning (DL) leads to improved memory performance compared with massed learning (ML) (i.e., spacing effect). However, the extent to which the hippocampus is involved in the spacing effect at shorter and longer retention intervals remains unclear. To address this issue, two groups of participants were asked to encode face-scene pairs at 20-min, 1-day, and 1-month intervals before they were scanned using fMRI during an associative recognition task. The pairs were repeated six times in either a massed (i.e., six times in 1 day) or a distributed (i.e., six times over 3 days, twice per day) manner. The results showed that compared with that in the ML group, the activation of the left hippocampus was stronger in the DL group when the participants retrieved old pairs correctly and rejected new pairs correctly at different retention intervals. In addition, the posterior hippocampus was more strongly activated when the new associations were rejected correctly after DL than ML, especially at the 1-month interval. Hence, our results provide evidence that the hippocampus is involved in better memory performance after DL compared to ML at both shorter and longer retention intervals.

Spaced Learning Enhances Episodic Memory by Increasing Neural Pattern Similarity Across Repetitions

Spaced learning has been shown consistently to benefit memory compared with massed learning, yet the neural representations and processes underlying the spacing effect are still poorly understood. In particular, two influential models (i.e., the encoding variability hypothesis and the study-phase retrieval hypothesis) could both model behavioral performance very well, but they make opposite hypotheses regarding the spacing effect's neural mechanisms. The present study attempted to provide empirical neural evidence to adjudicate these competing hypotheses. Using spatiotemporal pattern similarity (STPS) analysis of EEG data, this study investigated whether and how repetition lags (massed/short-spaced/long-spaced) modulated the STPS's contribution to episodic memory encoding in male and female human participants. The results revealed that greater item-specific STPS in the right frontal electrodes at 543-727 ms after stimulus onset was associated with better memory performance. More importantly, this STPS was larger under the spaced-learning condition than the massed-learning condition and partially mediated the spacing effect on memory performance. In addition, we found that massed learning was associated with stronger repetition suppression in the N400 component that reflected momentary retrieval strength, but reduced activity in the late positive component that was associated with memory retrieval. These results suggest that spaced learning improves long-term memory by increasing retrieval effort and enhancing the pattern reinstatement of prior neural representations, which may be achieved by reducing the momentary retrieval strength as the extended repetition lags might help to eliminate the residual representation in working memory.SIGNIFICANCE STATEMENT As one of the most ubiquitous and fundamental phenomena in the history of memory research, the spacing effect provides an important window into understanding how enduring memory is formed in the brain and how different practice strategies could modulate these mechanisms to affect memory performance. By leveraging the neural representational analysis on scalp EEG data, the current study provides the first empirical data to show that spaced learning enhances memory by improving the spatiotemporal similarity that occurs at a late time window. Our results support the study-phase retrieval hypothesis but not the encoding variability hypothesis and emphasize the role of neural pattern reinstatement in strengthening memory via repeated study.

Effects of modality and repetition in a continuous recognition memory task: Repetition has no effect on auditory recognition memory

Previous research has shown that auditory recognition memory is poorer compared to visual and cross-modal (visual and auditory) recognition memory. The effect of repetition on memory has been robust in showing improved performance. It is not clear, however, how auditory recognition memory compares to visual and cross-modal recognition memory following repetition. Participants performed a recognition memory task, making old/new discriminations to new stimuli, stimuli repeated for the first time after 4-7 intervening items (R1), or repeated for the second time after 36-39 intervening items (R2). Depending on the condition, participants were either exposed to visual stimuli (2D line drawings), auditory stimuli (spoken words), or cross-modal stimuli (pairs of images and associated spoken words). Results showed that unlike participants in the visual and cross-modal conditions, participants in the auditory recognition did not show improvements in performance on R2 trials compared to R1 trials. These findings have implications for pedagogical techniques in education, as well as for interventions and exercises aimed at boosting memory performance.

Unfamiliar faces in recognition memory: spaced learning enhances subsequent recognition memory by reducing repetition priming

Although the spacing effect is one of most robust effects in learning, its cognitive and neural mechanisms are still under investigation. Whether the spacing effect is achieved by reducing neural repetition priming or depends on learning experience is still unclear. In this event-related potential study, participants were asked to memorize 140 novel faces, half under the massed learning condition and the other half under the spaced learning condition. The afterwards recognition tests indicated that participants recognized more items under the spaced learning condition than under the massed learning condition. The electroencephalography data suggested that spaced learning was associated with a reduced familiarity effect in frontal N400. Remembered faces showed smaller repetition priming than forgotten faces under both learning conditions and spaced learning significantly reduced repetition suppression. Although no direct association was found between repetition priming and episodic memory, the difference in quantity between spaced learning and massed learning in the repetition priming can predict the different quantities in the recognition memory. These results suggest that the neural mechanism of the spacing effect is influenced by experience; however, the impact is mainly repetition priming and the spacing effect is still very robust.

Brain regions and functional interactions supporting early word recognition in the face of input variability

Perception and cognition in infants have been traditionally investigated using habituation paradigms, assuming that babies' memories in laboratory contexts are best constructed after numerous repetitions of the very same stimulus in the absence of interference. A crucial, yet open, question regards how babies deal with stimuli experienced in a fashion similar to everyday learning situations-namely, in the presence of interfering stimuli. To address this question, we used functional near-infrared spectroscopy to test 40 healthy newborns on their ability to encode words presented in concomitance with other words. The results evidenced a habituation-like hemodynamic response during encoding in the left-frontal region, which was associated with a progressive decrement of the functional connections between this region and the left-temporal, right-temporal, and right-parietal regions. In a recognition test phase, a characteristic neural signature of recognition recruited first the right-frontal region and subsequently the right-parietal ones. Connections originating from the right-temporal regions to these areas emerged when newborns listened to the familiar word in the test phase. These findings suggest a neural specialization at birth characterized by the lateralization of memory functions: the interplay between temporal and left-frontal regions during encoding and between temporo-parietal and right-frontal regions during recognition of speech sounds. Most critically, the results show that newborns are capable of retaining the sound of specific words despite hearing other stimuli during encoding. Thus, habituation designs that include various items may be as effective for studying early memory as repeated presentation of a single word.

Brain regions that show repetition suppression and enhancement: A meta-analysis of 137 neuroimaging experiments

Repetition suppression and enhancement refer to the reduction and increase in the neural responses for repeated rather than novel stimuli, respectively. This study provides a meta-analysis of the effects of repetition suppression and enhancement, restricting the data used to that involving fMRI/PET, visual stimulus presentation, and healthy participants. The major findings were as follows. First, the global topography of the repetition suppression effects was strikingly similar to that of the "subsequent memory" effects, indicating that the mechanism for repetition suppression is the reduced engagement of an encoding system. The lateral frontal cortex effects involved the frontoparietal control network regions anteriorly and the dorsal attention network regions posteriorly. The left fusiform cortex effects predominantly involved the dorsal attention network regions, whereas the right fusiform cortex effects mainly involved the visual network regions. Second, the category-specific meta-analyses and their comparisons indicated that most parts of the alleged category-specific regions showed repetition suppression for more than one stimulus category. In this regard, these regions may not be "dedicated cortical modules," but are more likely parts of multiple overlapping large-scale maps of simple features. Finally, the global topography of the repetition enhancement effects was similar to that of the "retrieval success" effects, suggesting that the mechanism for repetition enhancement is voluntary or involuntary explicit retrieval during an implicit memory task. Taken together, these results clarify the network affiliations of the regions showing reliable repetition suppression and enhancement effects and contribute to the theoretical interpretations of the local and global topography of these two effects. Hum Brain Mapp 38:1894-1913, 2017. © 2017 Wiley Periodicals, Inc.

Differential Neural Correlates Underlie Judgment of Learning and Subsequent Memory Performance

Judgment of learning (JOL) plays a pivotal role in self-regulated learning. Although the JOLs are in general accurate, important deviations from memory performance are often reported, especially when the JOLs are made immediately after learning. Nevertheless, existing studies have not clearly dissociated the neural processes underlying subjective JOL and objective memory. In the present study, participants were asked to study a list of words that would be tested 1 day later. Immediately after learning an item, participants predicted how likely they would remember that item. Critically, the JOL was performed on only half of the studied items to avoid its contamination on subsequent memory. We found that during encoding, compared to items later judged as "will be forgotten," those judged as "will be remembered" showed stronger activities in the default-mode network, including the ventromedial prefrontal cortex (PFC) and posterior cingulate cortex, as well as weaker functional connectivity between the left dorsolateral PFC and the visual cortex. The exact opposite pattern was found when comparing items that were actually remembered with those that were later forgotten. These important neural dissociations between JOL and memory performance shed light on the neural mechanisms of human metamemory bias.