Shallow Encoding Research Articles

Consolidation without intention: Sleep strengthens veridical and gist representations of information after incidental encoding.

Sleep strengthens declarative memory, but research investigating the effect of sleep on memory for information that is not explicitly studied for a test is sparse. In two experiments, we investigated the effect of sleep on gist-based and veridical representations of incidentally encoded information. Participants rated words from Deese-Roediger-McDermott (DRM) lists in either a deep or shallow encoding task and completed a surprise memory test after either sleep or wake. In Experiment 1, words were presented in lists, in order of descending associativity with the unpresented critical lure. Memory for list words and critical lures in both encoding tasks was stronger after sleep than wake, suggesting that sleep consolidated gist-based memory. In Experiment 2, the same words were presented in a random order across the experiment to minimize gist-based processing. Sleep strengthened veridical memory for list words following deep, but not shallow, encoding and did not affect critical lures. These results suggest sleep consolidates gist and veridical representations of information after incidental encoding, and that sleep-dependent consolidation processes may depend on processes at encoding, such as overlapping context and the strength of veridical memory traces.

Effects of exploring a novel environment on memory across the lifespan

Exploration of a novel environment has been shown to promote memory formation in healthy adults. Studies in animals have suggested that such novelty-induced memory boosts are mediated by hippocampal dopamine. The dopaminergic system is known to develop and deteriorate over the lifespan, but so far, the effects of novelty on memory across the lifespan have not yet been investigated. In the current study, we had children, adolescents, younger, and older adults (n = 439) explore novel and previously familiarized virtual environments to pinpoint the effects of spatial novelty on declarative memory in humans across different age groups. After exploration, words were presented while participants performed a deep or shallow encoding task. Incidental memory was quantified in a surprise test. Results showed that participants in the deep encoding condition remembered more words than those in the shallow condition, while novelty did not influence this effect. Interestingly, however, children, adolescents and younger adults benefitted from exploring a novel compared to a familiar environment as evidenced by better word recall, while these effects were absent in older adults. Our findings suggest that the beneficial effects of novelty on memory follow the deterioration of neural pathways involved in novelty-related processes across the lifespan.

On the estimation of traffic speeds with Deep Convolutional Neural Networks given probe data

This paper studies Deep Convolutional Neural Networks (DCNNs) for the accurate estimation of space–time traffic speeds given sparse data on freeways. Several aspects are highlighted which are crucial for the large-scale application of DCNNs to empirical probe data. (i) A methodology is proposed that allows to effectively train DCNNs on variable-sized space–time domains given empirical data prone to a varying penetration rate. Therefore, space–time domains are decomposed into small unified grids, which are processed separately. Second, in order to cope with varying penetration rates of available probe data, the network input is designed as two input matrices: grid-based speed data and grid occupancies. (ii) Using empirical probe data collected during 43 congestion scenarios on a freeway of 143 km length a shallow encoding–decoding CNN and a deep CNN are trained to reconstruct heterogeneous congestion types, such as moving and stationary congestion. It is demonstrated that for training only data of a single sparse data source is needed but no complete Ground Truth (GT), and still heterogeneous congestion types are reconstructed accurately. (iii) The estimation accuracy of a shallow encoding–decoding CNN and a DCNN, based on the U-net, are compared with traditional methods such as the ASM and PSM. An unseen complex congestion scenario is studied with all approaches and the estimation results are analyzed qualitatively and quantitatively. It is shown, that the DCNN outperforms the other approaches significantly.

Level of processing’s effect on episodic retrieval following traumatic brain injury in the elderly: An event-related potential study

Individuals who have sustained a traumatic brain injury (TBI) can suffer from episodic memory impairments. Until now, the neural correlates underlying episodic retrieval in individuals with TBI remained scarce, particularly in older adults. We aimed to fill this gap by recording event-related potentials during an old/new episodic recognition task in 26 older adults, 13 healthy and 13 with TBI. The task manipulated the level of processing in encoding with the use of semantic organizational strategies (deep guided, deep self-guided, and shallow encoding). For all encoding conditions, behavioral data analyses on the discrimination rate indicated that older adults with TBI were globally impaired compared with healthy older adults. The electrophysiological results indicated that the left-parietal effect was larger in the deep guided condition than in the shallow condition. In addition, the results show that the mid-frontal and left-parietal positive old/new effects were absent in both groups. The main findings are the observation, in the control group only, of an early frontal old/new effect (P200; 150–300 ms) and of a late frontal old/new effect on the left hemisphere, only in the Spontaneous condition. Together, results suggest an impairment of the allocation of attentional resources and working memory necessary for retrieving and monitoring items in the elderly with TBI.

032 Sleep Consolidates Memory for Strong but not Weak Information After Incidental Encoding

Abstract Introduction Slow wave sleep (SWS) strengthens memory for studied information, but research on the effect of sleep on information that is not intentionally remembered is scarce. Previous research from our lab suggests sleep consolidates some information that has been encoded incidentally, meaning that it has been acted on but not intentionally remembered. It remains unclear what determines which information is consolidated during sleep after incidental encoding and what aspects of sleep are related to this mnemonic benefit. In two experiments, we test the hypothesis that sleep consolidates strong but not weak memory traces following incidental encoding and assess the relationship between memory performance and sleep attributes. Methods In Experiment 1, we manipulated memory strength within- and between-subjects. Participants rated words one or three times (within) in a shallow or deep incidental encoding task (between). In the shallow task, participants counted vowels in each word; in the deep task, participants rated each word on a scale from ‘concrete’ to ‘abstract’. Following a 12-hour period containing sleep or wakefulness, participants took a surprise memory test. In Experiment 2, participants rated words one or three times in the deep encoding task, received an 8-hour sleep opportunity with partial PSG, and took the surprise memory test. Results In Experiment 1, participants remembered words better after sleep than wake regardless of number of encoding trials, but only after deep encoding. There was not an effect of sleep following shallow encoding. In Experiment 2, SWS correlated negatively with response latency for correctly recognized words encoded once, but not those encoded three times. That is, participants who received more SWS showed faster performance. Conclusion Results suggest sleep consolidated information based on the depth of encoding, and this benefit was related to SWS. This work is broadly consistent with theories of memory consolidation that predict sleep is more beneficial for strong than weak memory traces, such as the synaptic downscaling hypothesis. Support (if any):

0084 Sleep Consolidates Incidentally Encoded Information After Deep but Not Shallow Encoding

Abstract Introduction Slow wave sleep (SWS) strengthens declarative memory for information studied for a later test. However, research on the effect of sleep on information that is not intentionally remembered is scare. Previous research from our lab suggests sleep consolidates some, but not all, information that has been encoded incidentally, meaning that it has been acted on but not intentionally remembered. It remains unclear what determines which information benefits from sleep-dependent consolidation processes and what aspects of sleep are related to these mnemonic benefits. In two experiments, we test the hypothesis that sleep consolidates strong but not weak memory traces following incidental encoding, and assess the relationship between memory performance and objective sleep characteristics. Methods In Experiment 1, participants rated words one (weak traces) or three times (strong traces) in a deep or shallow incidental encoding task. Participants either rated words on a scale from ‘concrete’ to ‘abstract’ (deep) or counted the vowels in the words (shallow). Following a 12-hour period containing sleep or wakefulness, participants took a surprise memory test. In Experiment 2, participants rated words one or three times in the deep encoding task, received an 8-hour sleep opportunity with polysomnography, and took the surprise memory test. Results In Experiment 1, participants remembered words better after sleep than wake regardless of whether words were encoded one or three times, but only after deep encoding. Sleep did not consolidate information following shallow encoding. Experiment 2 is ongoing, but we predict that the amount of SWS will correlate positively with memory. Conclusion Results thus far suggest sleep may have consolidated information based on the strength of memory traces. Because deep encoding results in stronger memory traces than shallow encoding, this work is broadly consistent with theories of memory consolidation that predict sleep is more beneficial for strong memory traces than weak, such as the synaptic downscaling hypothesis. Support N/A

Discounting and Augmentation in Causal Conditional Reasoning: Causal Models or Shallow Encoding?

Recent research comparing mental models theory and causal Bayes nets for their ability to account for discounting and augmentation inferences in causal conditional reasoning had some limitations. One of the experiments used an ordinal scale and multiple items and analysed the data by subjects and items. This procedure can create a variety of problems that can be resolved by using an appropriate cumulative link function mixed models approach in which items are treated as random effects. Experiment 1 replicated this earlier experiment and analysed the results using appropriate data analytic techniques. Although successfully replicating earlier research, the pattern of results could be explained by a much simpler “shallow encoding” hypothesis. Experiment 2 introduced a manipulation to critically test this hypothesis. The results favoured the causal Bayes nets predictions and not shallow encoding and were not consistent with mental models theory. Experiment 1 provided qualified support for the causal Bayes net approach using appropriate statistics because it also replicated the failure to observe one of the predicted main effects. Experiment 2 discounted one plausible explanation for this failure. While within the limited goals that were set for these experiments they were successful, more research is required to account for the pattern of findings using this paradigm.

Comparing single- and dual-process models of memory development.

This experiment examined single-process and dual-process accounts of the development of visual recognition memory. The participants, 6-7-year-olds, 9-10-year-olds and adults, were presented with a list of pictures which they encoded under shallow or deep conditions. They then made recognition and confidence judgments about a list containing old and new items. We replicated the main trends reported by Ghetti and Angelini () in that recognition hit rates increased from 6 to 9years of age, with larger age changes following deep than shallow encoding. Formal versions of the dual-process high threshold signal detection model and several single-process models (equal variance signal detection, unequal variance signal detection, mixture signal detection) were fit to the developmental data. The unequal variance and mixture signal detection models gave a better account of the data than either of the other models. A state-trace analysis found evidence for only one underlying memory process across the age range tested. These results suggest that single-process memory models based on memory strength are a viable alternative to dual-process models for explaining memory development.

Mental Schemas Hamper Memory Storage of Goal-Irrelevant Information.

Mental schemas exert top-down control on information processing, for instance by facilitating the storage of schema-related information. However, given capacity-limits and competition in neural network processing, schemas may additionally exert their effects by suppressing information with low momentary relevance. In particular, when existing schemas suffice to guide goal-directed behavior, this may actually reduce encoding of the redundant sensory input, in favor of gaining efficiency in task performance. The present experiment set out to test this schema-induced shallow encoding hypothesis. Our approach involved a memory task in which faces had to be coupled to homes. For half of the faces the responses could be guided by a pre-learned schema, for the other half of the faces such a schema was not available. Memory storage was compared between schema-congruent and schema-incongruent items. To characterize putative schema effects, memory was assessed both with regard to visual details and contextual aspects of each item. The depth of encoding was also assessed through an objective neural measure: the parietal old/new ERP effect. This ERP effect, observed between 500–800 ms post-stimulus onset, is thought to reflect the extent of recollection: the retrieval of a vivid memory, including various contextual details from the learning episode. We found that schema-congruency induced substantial impairments in item memory and even larger ones in context memory. Furthermore, the parietal old/new ERP effect indicated higher recollection for the schema-incongruent than the schema-congruent memories. The combined findings indicate that, when goals can be achieved using existing schemas, this can hinder the in-depth processing of novel input, impairing the formation of perceptually detailed and contextually rich memory traces. Taking into account both current and previous findings, we suggest that schemas can both positively and negatively bias the processing of sensory input. An important determinant in this matter is likely related to momentary goals, such that mental schemas facilitate memory processing of goal-relevant input, but suppress processing of goal-irrelevant information.Highlights– Schema-congruent information suffers from shallow encoding.– Schema congruency induces poor item and context memory.– The parietal old/new effect is less pronounced for schema-congruent items.– Schemas exert different influences on memory formation depending on current goals.

Does long-term object priming depend on the explicit detection of object identity at encoding?

It is currently unclear whether objects have to be explicitly identified at encoding for reliable behavioral long-term object priming to occur. We conducted two experiments that investigated long-term object and non-object priming using a selective-attention encoding manipulation that reduces explicit object identification. In Experiment 1, participants either counted dots flashed within an object picture (shallow encoding) or engaged in an animacy task (deep encoding) at study, whereas, at test, they performed an object-decision task. Priming, as measured by reaction times (RTs), was observed for both types of encoding, and was of equivalent magnitude. In Experiment 2, non-object priming (faster RTs for studied relative to unstudied non-objects) was also obtained under the same selective-attention encoding manipulation as in Experiment 1, and the magnitude of the priming effect was equivalent between experiments. In contrast, we observed a linear decrement in recognition memory accuracy across conditions (deep encoding of Experiment 1 > shallow encoding Experiment 1 > shallow encoding of Experiment 2), suggesting that priming was not contaminated by explicit memory strategies. We argue that our results are more consistent with the identification/production framework than the perceptual/conceptual distinction, and we conclude that priming of pictures largely ignored at encoding can be subserved by the automatic retrieval of two types of instances: one at the motor level and another at an object-decision level.

Gender differences in word fragment and word stem completion memory tasks

Implicit memory tasks involve an increase in performance for previously seen items when compared to new items, independent of whether or not participants correctly classify the item as old. In this study we evaluated the effect of sex differences on word fragment (WFC) word stem completion (WSC) tasks, under the hypothesis that they would show no differences between tasks, and that women would overall perform better than men. 24 undergraduate students participated in this study, which consisted of a shallow encoding task, followed by a fragmented word completion task. Results did not reveal differences in performance between men and women on overall word completion rates. However, we found differences between WSC and WFC in men and women. Contrary to our hypothesis, women did not perform better than men.

Differential effects of acute cortisol administration on deep and shallow episodic memory traces: A study on healthy males

We aimed at investigating rapid effects of plasma cortisol elevations on the episodic memory phase of encoding or retrieval, and on the strength of the memory trace. Participants were asked either to select a word containing the letter “e” (shallow encoding task) or to judge if a word referred to a living entity (deep encoding task). We intravenously administered a bolus of 20mg of cortisol either 5min before encoding or 5min before retrieval, in a between-subjects design. The study included only male participants tested in the late afternoon, and neutral words as stimuli. When cortisol administration occurred prior to retrieval, a main effect of group emerged. Recognition accuracy was higher for individuals who received cortisol compared to placebo. The higher discrimination accuracy for the cortisol group was significant for words encoded during deep but not shallow task. Cortisol administration before encoding did not affect subsequent retrieval performance (either for deep or shallow stimuli) despite a facilitatory trend. Because genomic mechanisms take some time to develop, such a mechanism cannot apply to our findings where the memory task was performed shortly after the enhancement of glucocorticoid levels. Therefore, glucocorticoids, through non-genomic fast effects, determine an enhancement in episodic memory if administered immediately prior to retrieval. This effect is more evident if the memory trace is laid down through deep encoding operations involving the recruitment of specific neural networks.

What makes deeply encoded items memorable? Insights into the levels of processing framework from neuroimaging and neuromodulation.

When we form new memories, their mnestic fate largely depends upon the cognitive operations set in train during encoding. A typical observation in experimental as well as everyday life settings is that if we learn an item using semantic or “deep” operations, such as attending to its meaning, memory will be better than if we learn the same item using more “shallow” operations, such as attending to its structural features. In the psychological literature, this phenomenon has been conceptualized within the “levels of processing” framework and has been consistently replicated since its original proposal by Craik and Lockhart in 1972. However, the exact mechanisms underlying the memory advantage for deeply encoded items are not yet entirely understood. A cognitive neuroscience perspective can add to this field by clarifying the nature of the processes involved in effective deep and shallow encoding and how they are instantiated in the brain, but so far there has been little work to systematically integrate findings from the literature. This work aims to fill this gap by reviewing, first, some of the key neuroimaging findings on the neural correlates of deep and shallow episodic encoding and second, emerging evidence from studies using neuromodulatory approaches such as psychopharmacology and non-invasive brain stimulation. Taken together, these studies help further our understanding of levels of processing. In addition, by showing that deep encoding can be modulated by acting upon specific brain regions or systems, the reviewed studies pave the way for selective enhancements of episodic encoding processes.

Shallow Encoding and Forgetting Are Associated with Dependence in Instrumental Activities of Daily Living Among Older Adults Living with HIV Infection

Aging and HIV are both risk factors for memory deficits and declines in real-world functioning. However, we know little about the profile of memory deficits driving instrumental activities of daily living (IADL) declines across the lifespan in HIV. This study examined 145 younger (<50 years) and 119 older (≥50 years) adults with HIV who completed the California Verbal Learning Test-Second Edition (CVLT-II), the Wechsler Memory Scale-Third Edition Logical Memory subtest (WMS-III LM), and a modified Lawton and Brody ADL questionnaire. No memory predictors of IADL dependence emerged in the younger cohort. In the older group, IADL dependence was uniquely associated with worse performance on all primary CVLT-II variables, as well as elevated recency effects. Poorer immediate and delayed recall of the WMS-III LM was also associated with IADL dependence, although recognition was intact. Findings suggest older HIV-infected adults with shallow encoding and forgetting are at risk for IADL dependence.

Task-dependent Activity and Connectivity Predict Episodic Memory Network-based Responses to Brain Stimulation in Healthy Aging

BackgroundTranscranial magnetic stimulation (TMS) can affect episodic memory, one of the main cognitive hallmarks of aging, but the mechanisms of action remain unclear. ObjectivesTo evaluate the behavioral and functional impact of excitatory TMS in a group of healthy elders. MethodsWe applied a paradigm of repetitive TMS – intermittent theta-burst stimulation – over left inferior frontal gyrus in healthy elders (n = 24) and evaluated its impact on the performance of an episodic memory task with two levels of processing and the associated brain activity as captured by a pre and post fMRI scans. ResultsIn the post-TMS fMRI we found TMS-related activity increases in left prefrontal and cerebellum-occipital areas specifically during deep encoding but not during shallow encoding or at rest. Furthermore, we found a task-dependent change in connectivity during the encoding task between cerebellum-occipital areas and the TMS-targeted left inferior frontal region. This connectivity change correlated with the TMS effects over brain networks. ConclusionsThe results suggest that the aged brain responds to brain stimulation in a state-dependent manner as engaged by different tasks components and that TMS effect is related to inter-individual connectivity changes measures. These findings reveal fundamental insights into brain network dynamics in aging and the capacity to probe them with combined behavioral and stimulation approaches.

No effect of stress on false recognition.

The present study aimed to analyze the effect of acute stress on false recognition in the Deese/Roediger-McDermott (DRM) paradigm. In this paradigm, lists of words associated with a non-presented critical lure are studied and, in a subsequent memory test, critical lures are often falsely remembered. In two experiments, participants were randomly assigned to either the stress group (Trier Social Stress Test) or the no-stress control group. Because we sought to control the level-of-processing at encoding, in Experiment 1, participants created a visual mental image for each presented word (deep encoding). In Experiment 2, participants performed a shallow encoding (to respond whether each word contained the letter "o"). The results indicated that, in both experiments, as predicted, heart rate and STAI-S scores increased only in the stress group. However, false recognition did not differ across stress and no-stress groups. Results suggest that, although psychosocial stress was successfully induced, it does not enhance the vulnerability of individuals with acute stress to DRM false recognition, regardless of the level of processing.

P 132. Modulation of encoding-related networks by intermittent TBS stimulation in healthy aging

Question Memory dysfunction is one of the main cognitive hallmarks of aging. Repetitive Transcranial Magnetic Stimulation induces brain plasticity changes that may underlie its capacity to modulate associative memory in elders (Sole-Padulles et al., 2006). Memory recall also depends on the manner in which stimuli are encoded (Innocenti et al., 2010) (i.e. the depth or shallowness of the processing) according to level of processing (LOP) theory (Craik and Lockhart, 1972). Our aim was to investigate the impact of a single session of excitatory intermittent theta burst stimulation (iTBS) on behavioral outcomes and the expression of brain networks in healthy elders, related to an episodic memory task with two types of processing. Materials and methods After an initial MRI scanner and neuropsychological testing 21 healthy elder subjects (71.6yo.) were randomly assigned to Real ( n =11) or Sham iTBS group. Subjects underwent a baseline functional MRI session (Siemens 3T) followed by Real or Sham iTBS (MagVenture, MagPro x100 Opt; 80% AMT; 600pulses). iTBS was neuronavigated (Nexstim-NBS-eXimia) over the Left Inferior Frontal Gyrus (LIFG) (group coordinates from metanalysis (Kim, 2011)). Immediately after iTBS, subjects realized a second equivalent MRI session. The memory task consisted in 8 24″ block-design paradigm were subjects were instructed to try to remember words either using deep (i.e. semantic) or shallow (i.e. perceptual) encoding. Repeated stimuli were also presented for control purposes. After both MRI sessions participants performed a recognition memory test. Results In a three way ANOVA, only main effects of LOP ( p For fMRI results, we found a significant interaction in Encoding Deep>Repeated Deep in Left and Right occipital cortex and in Encoding Deep>Encoding Shallow contrast in the anterior LIFG (Fig. 1) and in Left visual cortex indicating that Real iTBS compared to Sham stimulation resulted in increased BOLD signal but only associated to deep encoding processes (positive slope differences). Furthermore, these areas corresponded to those related to deep memory encoding in our baseline analyses. Conclusion While failing to observe a behavioral effect, iTBS specifically modulated the expression of a brain network only when subjects engaged a cognitive process related to encoding at Deeper LOP. Within the general framework of the state-dependency postulates (Silvanto et al., 2008), we suggest that our results provide further first evidence, in a study combining neuroimaging and a behavioral paradigm in elder participants, of the importance of considering the interaction between the objective brain stimulation parameters with the functional state of the neuronal populations, to account for the brain responses to non-invasive brain stimulation studies in cognitive studies in aging population.

Costs and Benefits in Item-Method Directed Forgetting: Differential Effects of Encoding and Retrieval

ABSTRACT This study examined how encoding and retrieval factors affected directed forgetting costs and benefits in an item-method procedure. Experiment 1 used a typical item-method procedure and revealed a levels-of-processing effect in overall recall. However, the deep encoding condition showed a smaller directed forgetting effect than the shallow encoding conditions. More importantly, “remember” (R) words were selectively rehearsed as indicated by greater recall from the primacy portion of the list and more apt to be recalled before “forget” (F) words. Experiment 2 showed that a deep encoding operation reduced directed forgetting costs and that directed forgetting benefits occurred only when R words were recalled before F words. These findings supported the hypotheses that encoding manipulation affected directed forgetting costs and that directed forgetting benefits were associated with output order bias. Results were discussed in terms of mechanisms that produce item-method directed forgetting.

Event-related potential (ERP) evidence for fluency-based recognition memory

Two experiments investigated the influence of perceptual fluency on recognition memory. Words were studied using a shallow encoding task to decrease the contribution of recollection on recognition. Fluency was manipulated by blurring half of the test probes. Clarity varied randomly across trials in one experiment and was grouped into two blocks (clear and blurry) in the other experiment. Clarity did not influence recognition judgments or the ERP correlate of familiarity (FN400) when clarity was blocked across trials, but fluent probes (old and clear) elicited a more negative ERP than less fluent probes 280–400ms at parietal electrode sites. Random variations in clarity produced the opposite pattern of results because recognition judgments and FN400 amplitudes varied, whereas the early ERPs did not differ. The results are interpreted as evidence that blocking clarity across trials led to recognition that was based on repetition fluency differences (i.e., old more fluent than new), which was associated with an early (280–400ms) ERP at parietal electrodes in the absence of FN400 differences. Randomly varying clarity across trials created a situation where repetition fluency and perceptual fluency (i.e., probe clarity) interacted and led recognition to be based on familiarity/conceptual implicit memory that was associated with FN400 amplitudes in the absence of early ERP differences. The behavioral and ERP differences suggest that perceptual fluency, by itself, is capable of supporting recognition in some contexts and that, in other contexts, fluency can combine with other memory trace information to support recognition.

False memory and level of processing effect

Event-related potentials (ERPs) were used to determine the effects of level of processing on true and false memory, using the Deese-Roediger-McDermott (DRM) paradigm. In the DRM paradigm, lists of words highly associated to a single nonpresented word (the 'critical lure') are studied and, in a subsequent memory test, critical lures are often falsely remembered. Lists with three critical lures per list were auditorily presented here to participants who studied them with either a shallow (saying whether the word contained the letter 'o') or a deep (creating a mental image of the word) processing task. Visual presentation modality was used on a final recognition test. True recognition of studied words was significantly higher after deep encoding, whereas false recognition of nonpresented critical lures was similar in both experimental groups. At the ERP level, true and false recognition showed similar patterns: no FN400 effect was found, whereas comparable left parietal and late right frontal old/new effects were found for true and false recognition in both experimental conditions. Items studied under shallow encoding conditions elicited more positive ERP than items studied under deep encoding conditions at a 1000-1500 ms interval. These ERP results suggest that true and false recognition share some common underlying processes. Differential effects of level of processing on true and false memory were found only at the behavioral level but not at the ERP level.