Deep Encoding Research Articles

Differential attentional allocation and subsequent recognition for young and older adult faces

Studies examining own-age recognition biases report inconsistent results and often utilize paradigms that present faces individually and in isolation. We investigated young and older adults' attention towards young and older faces during learning and whether differential attention influences recognition. Participants viewed complex scenes while their eye movements were recorded; each scene contained two young and two older faces. Half of the participants formed scene impressions and half prepared for a memory test. Participants then completed an old/new face recognition task. Both age groups looked longer at young than older faces; however, only young adults showed an own-age recognition advantage. Participants in the memory condition looked longer at faces but did not show enhanced recognition relative to the impressions condition. Overall, attention during learning did not influence recognition. Our results provide evidence for a young adult face bias in attentional allocation but suggest that longer looking does not necessarily indicate deeper encoding.

Opposing effects of oxytocin on overt compliance and lasting changes to memory.

From infancy we learn to comply with societal norms. However, overt compliance is not necessarily accompanied by a change in internal beliefs. The neuromodulatory processes underlying these different phenomena are not yet understood. Here, we test the role of oxytocin in controlling overt compliance versus internalization of information delivered by a social source. After intranasal oxytocin administration, participants showed enhanced compliance to the erroneous opinion of others. However, this expression was coupled with a decrease in the influence of others on long-term memories. Our data suggest that this dissociation may result from reduced conflict in the face of social pressure, which increases immediate conforming behavior, but reduces processing required for deep encoding. These findings reveal a neurobiological control system that oppositely affects internalization and overt compliance.

Early neuropsychological detection of Alzheimer's disease.

Lifestyle modification offers a promising way of preventing or delaying Alzheimer's disease (AD). In particular, nutritional interventions can contribute to decrease the risk of dementia. The efficacy of such interventions should be assessed in individuals thought to be prone to AD. It is therefore necessary to identify markers that may help detecting AD as early as possible. This review will focus on subtle neuropsychological changes that may already exist in the predementia phase, and that could point to individuals at risk of dementia. Episodic memory decline appears consistently as the earliest sign of incipient typical AD. An episodic memory test that ensures deep encoding of information and assesses retrieval with free as well as cued recall appears as a useful tool to detect patients at an early stage of AD. Beyond the memory domain, category verbal fluency has been shown to decline early and to predict progression to AD. Moreover, in line with current diagnosis criteria for prodromal AD, combining neuropsychological scores and neuroimaging data allows a better discrimination of future AD patients than neuroimaging or neuropsychological data alone. Altogether, the detection of cognitive changes that are predictive of the typical form of probable AD already in the predementia stage points to at risk people who are the best target for therapeutic interventions, such as nutrition or physical exercise counseling or dietary interventions.

Effect of semantic coherence on episodic memory processes in schizophrenia

Schizophrenia is associated with severe episodic retrieval impairment. The aim of this study was to investigate the possibility that schizophrenia patients could improve their familiarity and/or recollection processes by manipulating the semantic coherence of to-be-learned stimuli and using deep encoding. Twelve schizophrenia patients and 12 healthy controls of comparable age, gender, and educational level undertook an associative recognition memory task. The stimuli consisted of pairs of words that were either related or unrelated to a given semantic category. The process dissociation procedure was used to calculate the estimates of familiarity and recollection processes. Both groups showed enhanced memory performances for semantically related words. However, in healthy controls, semantic relatedness led to enhanced recollection, while in schizophrenia patients, it induced enhanced familiarity. The familiarity estimates for related words were comparable in both groups, indicating that familiarity could be used as a compensatory mechanism in schizophrenia patients.

The role of the frontal cortex in memory: an investigation of the Von Restorff effect.

Evidence from neuropsychology and neuroimaging indicate that the pre-frontal cortex (PFC) plays an important role in human memory. Although frontal patients are able to form new memories, these memories appear qualitatively different from those of controls by lacking distinctiveness. Neuroimaging studies of memory indicate activation in the PFC under deep encoding conditions, and under conditions of semantic elaboration. Based on these results, we hypothesize that the PFC enhances memory by extracting differences and commonalities in the studied material. To test this hypothesis, we carried out an experimental investigation to test the relationship between the PFC-dependent factors and semantic factors associated with common and specific features of words. These experiments were performed using Free-Recall of word lists with healthy adults, exploiting the correlation between PFC function and fluid intelligence. As predicted, a correlation was found between fluid intelligence and the Von-Restorff effect (better memory for semantic isolates, e.g., isolate “cat” within category members of “fruit”). Moreover, memory for the semantic isolate was found to depend on the isolate's serial position. The isolate item tends to be recalled first, in comparison to non-isolates, suggesting that the process interacts with short term memory. These results are captured within a computational model of free recall, which includes a PFC mechanism that is sensitive to both commonality and distinctiveness, sustaining a trade-off between the two.

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.

Benefits of deep encoding in Alzheimer's disease. Analysis of performance in a memory task using the Item Specific Deficit Approach

IntroductionThe aim of this study was to test the encoding deficit hypothesis in Alzheimer disease (AD) using a recent method for correcting memory tests. To this end, a Spanish-language adaptation of the Free and Cued Selective Reminding Test was interpreted using the Item Specific Deficit Approach (ISDA), which provides three indices: Encoding Deficit Index, Consolidation Deficit Index, and Retrieval Deficit Index. MethodsWe compared the performances of 15 patients with AD and 20 healthy control subjects and analysed results using either the task instructions or the ISDA. ResultsPatients with AD displayed deficient encoding of more than half the information, but items that were encoded properly could be retrieved later with the help of the same semantic clues provided individually during encoding. Virtually all the information retained over the long term was retrieved by using semantic clues. Encoding was shown to be the most impaired process, followed by retrieval and consolidation. Discriminant function analyses showed that ISDA indices are more sensitive and specific for detecting memory impairments in AD than are raw scores. ConclusionsThese results indicate that patients with AD present impaired information encoding, but they benefit from semantic hints that help them recover previously learned information. This should be taken into account for intervention techniques focusing on memory impairments in AD.

Reactivation of antecedents by overt vs null pronouns: Evidence from Persian

In Persian, a construction exists in which a gap can optionally be replaced by an overt pronoun. A self-paced reading study (110 participants) suggests that the overt pronoun results in deeper encoding (higher activation) of the antecedent noun, presumably because of richer retrieval cue specifications during antecedent retrieval at the pronoun; this higher activation has the consequence that the antecedent is easier to retrieve at a subsequent stage. This provides new evidence for reactivation effects of the type assumed in the cue-based retrieval model of parsing (Lewis and Vasishth, 2005), and shows that dependency resolution is not simply a matter of connecting two co-dependents; the retrieval cue specification has a differential impact on processing.

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.

Effects of aging and divided attention on episodic feeling-of-knowing accuracy

This research investigated the effect of aging on episodic feeling-of-knowing (FOK) using a divided attention (DA) paradigm in order to examine whether DA in younger adults mimics the effects of aging when decreasing either memory encoding or monitoring processes. To that end, four groups of participants were tested on the FOK task: young adults (control group), young adults under DA at encoding, young adults under DA when making FOK judgments, and older adults. Our results showed that DA at encoding in young adults mimicked the effect of aging on memory performance, and also on FOK magnitude and accuracy, supporting the memory-constraint hypothesis (Hertzog et al., 2010). However, our results do not completely contradict the monitoring-deficit hypothesis, as DA during FOK judgments also affected FOK accuracy, but to a lesser extent than the aging effect or DA during encoding. We suggest that the age-related FOK deficit may be due to a lower level of deep encoding, leading to difficulty retrieving target-related contextual details enabling accurate prediction of subsequent recognition.

Retrieval practice and elaborative encoding benefit memory in younger and older adults

Retrieval practice has been identified as a powerful tool for promoting retention. Few studies have examined whether retrieval practice enhances performance in older adults as it does in younger adults. Younger and older adults learned unrelated word pairs and were administered a test after a short (10min) and long (2 day) delay. Encoding condition was manipulated between subjects, with participants studying the pairs twice, studying them once and taking an immediate test with feedback, or encoding them twice under different deep encoding conditions. In both age groups, equivalent benefits of testing relative to restudy were found. Deep processing also improved memory relative to restudy, suggesting that one factor that might benefit retention is varying the type of encoding task (either by testing or by providing a different instructional manipulation) to increase the accessibility of cues. Retrieval practice can support older adults’ memory and is a viable target for training.

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.

Stress Sensitizes the Brain: Increased Processing of Unpleasant Pictures after Exposure to Acute Stress

A key component of acute stress is a surge in vigilance that enables a prioritized processing of highly salient information to promote the organism's survival. In this study, we investigated the neural effects of acute stress on emotional picture processing. ERPs were measured during a deep encoding task, in which 40 male participants categorized 50 unpleasant and 50 neutral pictures according to arousal and valence. Before picture encoding, participants were subjected either to the Socially Evaluated Cold Pressor Test (SECPT) or to a warm water control procedure. The exposure to the SECPT resulted in increased subjective and autonomic (heart rate and blood pressure) stress responses relative to the control condition. Viewing of unpleasant relative to neutral pictures evoked enhanced late positive potentials (LPPs) over centro-parietal scalp sites around 400 msec after picture onset. Prior exposure to acute stress selectively increased the LPPs for unpleasant pictures. Moreover, the LPP magnitude for unpleasant pictures following the SECPT was positively associated with incidental free recall performance 24 hr later. The present results suggest that acute stress sensitizes the brain for increased processing of cues in the environment, particularly priming the processing of unpleasant cues. This increased processing is related to later long-term memory performance.

Face–Name Association Learning and Brain Structural Substrates in Alcoholism

Associative learning is required for face-name association and is impaired in alcoholism, but the cognitive processes and brain structural components underlying this deficit remain unclear. It is also unknown whether prompting alcoholics to implement a deep level of processing during face-name encoding would enhance performance. Abstinent alcoholics and controls performed a levels-of-processing face-name learning task. Participants indicated whether the face was that of an honest person (deep encoding) or that of a man (shallow encoding). Retrieval was examined using an associative (face-name) recognition task and a single-item (face or name only) recognition task. Participants also underwent 3T structural MRI. Compared with controls, alcoholics had poorer associative and single-item learning and performed at similar levels. Level of processing at encoding had little effect on recognition performance but affected reaction time (RT). Correlations with brain volumes were generally modest and based primarily on RT in alcoholics, where the deeper the processing at encoding, the more restricted the correlations with brain volumes. In alcoholics, longer control task RTs correlated modestly with smaller tissue volumes across several anterior to posterior brain regions; shallow encoding correlated with calcarine and striatal volumes; deep encoding correlated with precuneus and parietal volumes; and associative recognition RT correlated with cerebellar volumes. In controls, poorer associative recognition with deep encoding correlated significantly with smaller volumes of frontal and striatal structures. Despite prompting, alcoholics did not take advantage of encoding memoranda at a deep level to enhance face-name recognition accuracy. Nonetheless, conditions of deeper encoding resulted in faster RTs and more specific relations with regional brain volumes than did shallow encoding. The normal relation between associative recognition and corticostriatal volumes was not present in alcoholics. Rather, their speeded RTs occurred at the expense of accuracy and were related most robustly to cerebellar volumes.

The Neural Substrates of Memory Suppression: A fMRI Exploration of Directed Forgetting

The directed forgetting paradigm is frequently used to determine the ability to voluntarily suppress information. However, little is known about brain areas associated with information to forget. The present study used functional magnetic resonance imaging to determine brain activity during the encoding and retrieval phases of an item-method directed forgetting recognition task with neutral verbal material in order to apprehend all processing stages that information to forget and to remember undergoes. We hypothesized that regions supporting few selective processes, namely recollection and familiarity memory processes, working memory, inhibitory and selection processes should be differentially activated during the processing of to-be-remembered and to-be-forgotten items. Successful encoding and retrieval of items to remember engaged the entorhinal cortex, the hippocampus, the anterior medial prefrontal cortex, the left inferior parietal cortex, the posterior cingulate cortex and the precuneus; this set of regions is well known to support deep and associative encoding and retrieval processes in episodic memory. For items to forget, encoding was associated with higher activation in the right middle frontal and posterior parietal cortex, regions known to intervene in attentional control. Items to forget but nevertheless correctly recognized at retrieval yielded activation in the dorsomedial thalamus, associated with familiarity-based memory processes and in the posterior intraparietal sulcus and the anterior cingulate cortex, involved in attentional processes.

Bilingual recognition memory: Stronger performance but weaker levels-of-processing effects in the less fluent language

The effects of bilingual proficiency on recognition memory were examined in an experiment with Spanish-English bilinguals. Participants learned lists of words in English and Spanish under shallow- and deep-encoding conditions. Overall, hit rates were higher, discrimination greater, and response times shorter in the nondominant language, consistent with effects previously observed for lower frequency words. Levels-of-processing effects in hit rates, discrimination, and response time were stronger in the dominant language. Specifically, with shallow encoding, the advantage for the nondominant language was larger than with deep encoding. The results support the idea that memory performance in the nondominant language is impacted by both the greater demand for cognitive resources and the lower familiarity of the words.

The Influence of Sentential Position on Noun Phrase Structure Priming

This article explores the interaction between global sentence context and local syntactic decision making. Specifically, four noun phrase (NP) structural priming experiments investigated whether the position of an NP within a sentence increased speakers' tendency to repeat primed structure. We crossed the position of the NP with the structure of the NP, such that NPs could be sentence initial or final in prime sentences. We further manipulated whether the to-be-modified target NP was sentence initial or final. Structural persistence effects were consistently observed, but there was no influence of parallel position. Rather, sentence-initial NP primes had a stronger influence on subsequent syntactic decisions than sentence-final primes, suggesting a primacy effect. Sentence-initial target NPs contributed to this primacy effect, while sentence-final target NPs did not. We argue that this primacy effect arises as the result of greater processing demands and resources for early than for late sentence constituents as well as deeper encoding and more focused attention when processing the beginnings of sentences.