Pragmatics of measuring recognition memory: Applications to dementia and amnesia

Agency effects on the binding of event elements in episodic memory

Representing events in episodic memory in a coherent manner requires that their constituent elements are bound together. So far, only few moderators of these binding processes have been identified. Here we investigate whether the presence of an agentic element in an event facilitates binding. The results from six experiments provided no evidence for a facilitating effect of agency on the binding of event elements. In addition, binding effects were only found when event elements were presented simultaneously, but not when they were presented sequentially pairwise, contrary to previous findings. The results suggest that the presence of an agentic element in an event does not, or only to a very limited extent, contribute to the formation of coherent memory representations and that additional processes may be required when binding event elements across temporarily divided encoding episodes. These findings add to a growing body of research regarding moderators and processes relevant for the binding of event elements in episodic memory. Explanations of these findings and directions for future research are discussed.

Influence of noninvasive brain stimulation on connectivity and local activation: a combined tDCS and fMRI study

The effect of transcranial direct current stimulation (tDCS) on neurobiological mechanisms underlying executive function in the human brain remains elusive. This study aims at examining the effect of anodal and cathodal tDCS over the left dorsolateral prefrontal cortex (DLPFC) in comparison with sham stimulation on resting-state connectivity as well as functional activation and working memory performance. We hypothesized perturbed fronto-parietal resting-state connectivity during stimulation and altered working memory performance combined with modified functional working memory-related activation. We applied tDCS with 1 mA for 21 min over the DLPFC inside an fMRI scanner. During stimulation, resting-state fMRI was acquired and task-dependent fMRI during working memory task performance was acquired directly after stimulation. N = 36 healthy subjects were studied in a within-subject design with three different experimental conditions (anodal, cathodal and sham) in a double-blind design. Seed-based functional connectivity analyses and dynamic causal modeling were conducted for the resting-state fMRI data. We found a significant stimulation by region interaction in the seed-based ROI-to-ROI resting-state connectivity, but no effect on effective connectivity. We also did not find an effect of stimulation on task-dependent signal alterations in working memory activation in our regions of interest and no effect on working memory performance parameters. We found effects on measures of seed-based resting-state connectivity, while measures of effective connectivity and task-based connectivity did not show any stimulation effect. We could not replicate previous findings of tDCS stimulation effects on behavioral outcomes. We critically discuss possible methodological limitations and implications for future studies.

Control strategy under pressure situations: performance pressure conditionally enhances proactive control

Previous research and theories have demonstrated that attentional control plays a crucial role in explaining the choking phenomenon (i.e., the performance decrements) under pressure situations. Attentional control is thought to function through two distinct control strategies: proactive control (i.e., a sustained and anticipatory strategy of control) and reactive control (i.e., a transient strategy of control). However, little is known about how performance pressure affects these control strategies. The present study was designed to address this issue. Participants were instructed to complete a continuous performance task (AX-CPT40) under pressure situations. The results showed that individuals under high-pressure situations tended to use proactive control rather than reactive control. Moreover, performance pressure resulted in a more liberal response bias following an A-cue, consistent with an increased use of proactive control. Importantly, the proactive behavioral index calculated on RTs showed that the increased proactive control mainly occurred in the short interval between the cue and probe, but not in the long interval. This suggests that individuals under high-pressure situations are unlikely to employ a proactive control strategy in a situation that requires more attentional resources. In summary, our results provide initial evidence that performance pressure conditionally enhances proactive control, which contributes to a deeper understanding of the dynamic adjustment of control strategies under pressure situations.

Ultrahigh Field fMRI Reveals Different Roles of the Temporal and Frontoparietal Cortices in Subjective Awareness

A central question in consciousness theories is whether one is dealing with a dichotomous ("all-or-none") or a gradual phenomenon. In this 7T fMRI study, we investigated whether dichotomy or gradualness in fact depends on the brain region associated with perceptual awareness reports. Both male and female human subjects performed an emotion discrimination task (fear vs neutral bodies) presented under continuous flash suppression with trial-based perceptual awareness measures. Behaviorally, recognition sensitivity increased linearly with increased stimuli awareness and was at chance level during perceptual unawareness. Physiologically, threat stimuli triggered a slower heart rate than neutral ones during "almost clear" stimulus experience, indicating freezing behavior. Brain results showed that activity in the occipitotemporal, parietal, and frontal regions as well as in the amygdala increased with increased stimulus awareness while early visual areas showed the opposite pattern. The relationship between temporal area activity and perceptual awareness best fitted a gradual model while the activity in frontoparietal areas fitted a dichotomous model. Furthermore, our findings illustrate that specific experimental decisions, such as stimulus type or the approach used to evaluate awareness, play pivotal roles in consciousness studies and warrant careful consideration.

Eye movement differences when recognising and learning moving and static faces

Seeing a face in motion can help subsequent face recognition. Several explanations have been proposed for this "motion advantage," but other factors that might play a role have received less attention. For example, facial movement might enhance recognition by attracting attention to the internal facial features, thereby facilitating identification. However, there is no direct evidence that motion increases attention to regions of the face that facilitate identification (i.e., internal features) compared with static faces. We tested this hypothesis by recording participants' eye movements while they completed the famous face recognition (Experiment 1, N = 32), and face-learning (Experiment 2, N = 60, Experiment 3, N = 68) tasks, with presentation style manipulated (moving or static). Across all three experiments, a motion advantage was found, and participants directed a higher proportion of fixations to the internal features (i.e., eyes, nose, and mouth) of moving faces versus static. Conversely, the proportion of fixations to the internal non-feature area (i.e., cheeks, forehead, chin) and external area (Experiment 3) was significantly reduced for moving compared with static faces (all ps < .05). Results suggest that during both familiar and unfamiliar face recognition, facial motion is associated with increased attention to internal facial features, but only during familiar face recognition is the magnitude of the motion advantage significantly related functionally to the proportion of fixations directed to the internal features.

Age differences in functional connectivity track dedifferentiation of category representations

With advancing age, the distinctiveness of neural representations of information declines. While the finding of this so-called 'age-related neural dedifferentiation' in category-selective neural regions is well-described, the contribution of age-related changes in network organization to dedifferentiation is unknown. Here, we asked whether age differences in a) whole-brain network segregation (i.e., network dedifferentiation) and b) functional connectivity to category-selective neural regions contribute to regional dedifferentiation of categorical representations. Younger and older adults viewed blocks of face and house stimuli in the fMRI scanner. We found an age-related decline in neural distinctiveness for faces in the fusiform gyrus (FG) and for houses in the parahippocampal gyrus (PHG). Functional connectivity analyses revealed age-related dedifferentiation of global network structure as well as age differences in connectivity between the FG and early visual cortices. Interindividual correlations demonstrated that regional distinctiveness was related to network segregation as well as connectivity of the FG to the visual network. Together, our findings reveal that dedifferentiation of categorical representations may be linked to age-related reorganization of functional networks.

Investigating the Effect of Contextual Cueing with Face Stimuli on Electrophysiological Measures in Younger and Older Adults

Extracting repeated patterns from our surroundings plays a crucial role in contextualizing information, making predictions, and guiding our behavior implicitly. Previous research showed that contextual cueing enhances visual search performance in younger adults. In this study, we investigated whether contextual cueing could also improve older adults' performance and whether age-related differences in the neural processes underlying implicit contextual learning could be detected. Twenty-four younger and 25 older participants performed a visual search task with contextual cueing. Contextual information was generated using repeated face configurations alongside random new configurations. We measured RT difference between new and repeated configurations; ERPs to uncover the neural processes underlying contextual cueing for early (N2pc), intermediate (P3b), and late (r-LRP) processes; and multiscale entropy and spectral power density analyses to examine neural dynamics. Both younger and older adults showed similar contextual cueing benefits in their visual search efficiency at the behavioral level. In addition, they showed similar patterns regarding contextual information processing: Repeated face configurations evoked decreased finer timescale entropy (1-20 msec) and higher frequency band power (13-30 Hz) compared with new configurations. However, we detected age-related differences in ERPs: Younger, but not older adults, had larger N2pc and P3b components for repeated compared with new configurations. These results suggest that contextual cueing remains intact with aging. Although attention- and target-evaluation-related ERPs differed between the age groups, the neural dynamics of contextual learning were preserved with aging, as both age groups increasingly utilized more globally grouped representations for repeated face configurations during the learning process.

Effects of emotional ambiguity and emotional intensity on true and false memory

Whereas the effects of emotional intensity (the perceived strength of an item's valence or arousal) have long been studied in true- and false-memory research, emotional ambiguity (the uncertainty that attaches to perceived emotional intensity) has only been studied recently. Available evidence suggests that emotional ambiguity has reliable effects on true memory that are distinct from those of emotional intensity. However, those findings are mostly restricted to recall, and the effects of emotional ambiguity on false memory remain unexplored. The current study addressed both limitations by measuring the effects of emotional ambiguity and emotional intensity on true and false recognition. In two experiments, we manipulated valence ambiguity and valence intensity (Experiment 1) and arousal ambiguity and arousal intensity (Experiment 2) of Deese/Roediger/McDermott lists. Multiple linear regression analyses were conducted for Experiment 1, Experiment 2, and the combined data of the experiments to separate the effects of emotional ambiguity and emotional intensity. Our results showed that both valence ambiguity and arousal ambiguity improved true recognition, and the effects of valence ambiguity remained robust even when controlling for valence intensity, arousal intensity, and arousal ambiguity. More importantly, for both valence and arousal, there was an interaction between ambiguity and intensity in false memory. Specifically, we found that valence ambiguity increased false recognition with positive valence, while arousal ambiguity amplified the effect of arousal intensity on false recognition. Our results are discussed in the context of the emotional ambiguity hypothesis and fuzzy-trace theory.

Multiple group membership and executive function in a socioeconomically diverse sample

Belonging to multiple groups is an important feature of our social lives. However, it is largely unknown if it is related to individual differences in cognitive performance. Given that changing self-identities linked to each group requires cognitive operations on knowledge bases associated with each group, the extent to which people belong to multiple groups may be related to individual differences in cognitive performance. Therefore, the main objective of this study was to test if multiple group membership is related to executive function task performance. A socioeconomically diverse sample of 395 individuals in Indonesia participated in this study. Our results show that multiple group membership was positively related to the 3-back working memory performance. However, we also found that this relationship was significant only among participants with high (not median or low) SES. We also observed that Contact diversity was negatively related to working memory performance among participants with low SES. Our results show that the complexity of our social lives is related to individual differences in executive function performance, although this seems to be constrained by SES.

Effect of emotional valence on true and false recognition controlling arousal

The aim of our experiment was to analyse the effect of the emotional valence (positive, negative, or neutral) on true and false recognition, matching the arousal, frequency, concreteness, and associative strength of the study and recognition words. Fifty younger adults and 46 healthy older adults performed three study tasks (with words of different valence: positive, negative, neutral) and their corresponding recognition tests. Two weeks later, they performed the three recognition tests again. The results show that words with a negative valence produced less true recognition and less false recognition than words with a positive or neutral valence, in both younger and older adults, on the immediate recognition test. This pattern of results was also found in the younger adults on the delayed recognition test, whereas in the older participants, these differences disappeared. Thus, when arousal is controlled, both younger and older adults tend to recognise negative information worse than positive or neutral information, but they also commit fewer errors. Results would suggest that the greater arousal commonly associated with negative stimuli, rather than their own valence, could explain some of the contradictory results found in the literature.

Somatic symptom distress is not related to cardioceptive accuracy

OBJECTIVE

(Cardiac) interoception was long considered a key mechanism behind symptom perception in persistent somatic symptoms (PSS). In this study, we aimed to extend earlier findings to clarify this potential interoceptive mechanisms of PSS.

METHODS

A cross-sectional sample of 251 participants (23.1% with self-reported functional somatic syndrome) completed a laboratory study with two cardioceptive accuracy tasks (Schandry task and a new cardiac signal detection task) and multiple questionnaires. Somatic symptom distress and associated constructs were assessed with the PHQ-15, as well as with a novel multidimensional questionnaire measure (HiTOP-SF1) derived from the somatoform spectrum of the Hierarchical Taxonomy of Psychopathology (HiTOP). Correlations (frequentist and Bayesian) and structural equation modelling (SEM) helped further investigate the interplay between these variables.

RESULTS

There were no significant correlations between measures of interoception and somatic symptom distress. Self-report and behavioral cardioceptive accuracy measures did not correlate significantly. No significant covariances emerged between diagnostic tools and cardioceptive accuracy; Bayesian analyses supported the lack of association between interoception and symptom perception.

CONCLUSIONS

Cardiac interoception (specifically cardioceptive accuracy) unlikely represents a key mechanism in PSS etiology. We recommend investigating other factors in PSS.

Pupillary correlates of individual differences in n-back task performance

We used pupillometry during a 2-back task to examine individual differences in the intensity and consistency of attention and their relative role in a working memory task. We used sensitivity, or the ability to distinguish targets (2-back matches) and nontargets, as the measure of task performance; task-evoked pupillary responses (TEPRs) as the measure of attentional intensity; and intraindividual pretrial pupil variability as the measure of attentional consistency. TEPRs were greater on target trials compared with nontarget trials, although there was no difference in TEPR magnitude when participants answered correctly or incorrectly to targets. Importantly, this effect interacted with performance: high performers showed a greater separation in their TEPRs between targets and nontargets, whereas there was little difference for low performers. Further, in regression analysis, larger TEPRs on target trials predicted better performance, whereas larger TEPRs on nontarget trials predicted worse performance. Sensitivity positively correlated with average pretrial pupil diameter and negatively correlated with intraindividual variability in pretrial pupil diameter. Overall, we found evidence that both attentional intensity (TEPRs) and consistency (pretrial pupil variation) predict performance on an n-back working memory task.

How emotional contexts modulate item memory in individuals with high and low negative affect and worry

Emotional stimuli are usually remembered with high confidence. Yet, it remains unknown whether-in addition to memory for the emotional stimulus itself-memory for a neutral stimulus encountered just after an emotional one can be enhanced. Further, little is known about the interplay between emotion elicited by a stimulus and emotion relating to affective dispositions. To address these questions, we examined (1) how emotional valence and arousal of a context image preceding a neutral item image affect memory of the item, and (2) how such memory modulation is affected by two hallmark features of emotional disorders: trait negative affect and tendency to worry. In two experiments, participants encoded a series of trials in which an emotional (negative, neutral, or positive) context image was followed by a neutral item image. In experiment 1 (n = 42), items presented seconds after negative context images were remembered better and with greater confidence compared to those presented after neutral and positive ones. Arousal ratings of negative context images were higher compared to neutral and positive ones and the likelihood of correctly recognizing an item image was related to higher arousal of the context image. In experiment 2 (n = 59), better item memory was related to lower trait negative affect. Participants with lower trait negative affect or tendency to worry displayed higher confidence compared to those with high negative affect or tendency to worry. Our findings describe an emotional "carry-over" effect elicited by a context image that enhances subsequent item memory on a trial-by-trial basis, however, not in individuals with high trait negative affect who seem to have a general memory disadvantage.

Detecting implicit and explicit facial emotions at different ages

Emotions are processed in the brain through a cortical route, responsible for detailed-conscious recognition and mainly based on image High Spatial Frequencies (HSF), and a subcortical route, responsible for coarse-unconscious processing and based on Low SF (LSF). However, little is known about possible changes in the functioning of the two routes in ageing. In the present go/no-go online task, 112 younger adults and 111 older adults were asked to press a button when a happy or angry face appeared (go) and to inhibit responses for neutral faces (no-go). Facial stimuli were presented unfiltered (broadband image), filtered at HSF and LSF, and hybrids (LSF of an emotional expression superimposed to the HSF of the same face with a neutral expression). All stimuli were also presented rotated on the vertical axis (upside-down) to investigate the global analysis of faces in ageing. Results showed an overall better performance of younger compared to older participants for all conditions except for hybrid stimuli. The expected face-inversion effect was confirmed in both age groups. We conclude that, besides an overall worsening of the perceptual skill with ageing, no specific impairment in the functioning of both the cortical and the subcortical route emerged.

Acute Angiotensin II Receptor Blockade Facilitates Parahippocampal Processing During Memory Encoding in High-Trait-Anxious Individuals

Background

Angiotensin II receptor blockers (ARBs) have been associated with preventing posttraumatic stress disorder symptom development and improving memory. However, the underlying neural mechanisms are poorly understood. This study investigated ARB effects on memory encoding and hippocampal functioning that have previously been implicated in posttraumatic stress disorder development.

Methods

In a double-blind randomized design, 40 high-trait-anxious participants (33 women) received the ARB losartan (50 mg) or placebo. At drug peak level, participants encoded images of animals and landscapes before undergoing functional magnetic resonance imaging, where they viewed the encoded familiar images and unseen novel images to be memorized and classified as animals/landscapes. Memory recognition was assessed 1 hour after functional magnetic resonance imaging. To analyze neural effects, whole-brain analysis, hippocampus region-of-interest analysis, and exploratory multivariate pattern similarity analysis were employed.

Results

ARBs facilitated parahippocampal processing. In the whole-brain analysis, losartan enhanced brain activity for familiar images in the parahippocampal gyrus (PHC), anterior cingulate cortex, and caudate. For novel images, losartan enhanced brain activity in the PHC only. Pattern similarity analysis showed that losartan increased neural stability in the PHC when processing novel and familiar images. However, there were no drug effects on memory recognition or hippocampal activation.

Conclusions

Given that the hippocampus receives major input from the PHC, our findings suggest that ARBs may modulate higher-order visual processing through parahippocampal involvement, potentially preserving intact memory input. Future research needs to directly investigate whether this effect may underlie the preventive effects of ARBs in the development of posttraumatic stress disorder.

Social evaluative stress enhances central detail memory, reduces false memory, and results in intrusive memories that last for days

Few studies have quantified what an individual remembers about a laboratory-controlled stressor. Here, we aimed to replicate previous work by using a modified version of the Trier Social Stress Test (TSST) to quantify participant memory for a stressful experience. We also aimed to extend this work by quantifying false and intrusive memories that ensued. One hundred and seven participants were exposed to the TSST (stress) or the friendly TSST (f-TSST; no stress). The TSST required participants to deliver a ten-minute speech in front of two laboratory panel members as part of a mock job interview; the f-TSST required participants to casually converse with the panel members about their interests. In both conditions, the panel members interacted with (central) or did not interact with (peripheral) several objects sitting on a desk in front of them. The next day, participants' memory for the objects was assessed with recall and recognition tests. We also quantified participants' intrusive memories on Days 2, 4, 6, and 8. Stressed participants recalled more central objects and exhibited greater recognition memory, particularly for central objects, than controls. Stress also led to less false recall and more intrusive memories on Days 2 and 4. Consistent with previous work, these findings suggest that participants exhibit enhanced memory for the central details of a stressful experience; they also extend prior work by showing that participants exposed to a stressor have less false memories and experience intrusive memories for several days following the event. The modified TSST paradigm used here may be useful for researchers studying not only what participants remember about a stressful event but also their susceptibility to intrusive memory formation.

Early visual cortices reveal interrelated item and category representations in aging

Neural dedifferentiation, the finding that neural representations tend to be less distinct in older adults compared with younger adults, has been associated with age-related declines in memory performance. Most studies assessing the relation between memory and neural dedifferentiation have evaluated how age impacts the distinctiveness of neural representations for different visual categories (e.g., scenes and objects). However, how age impacts the quality of neural representations at the level of individual items is still an open question. Here, we present data from an age-comparative fMRI study that aimed to understand how the distinctiveness of neural representations for individual stimuli differs between younger and older adults and relates to memory outcomes. Pattern similarity searchlight analyses yielded indicators of neural dedifferentiation at the level of individual items as well as at the category level in posterior occipital cortices. We asked whether age differences in neural distinctiveness at each representational level were associated with inter- and/or intraindividual variability in memory performance. While age-related dedifferentiation at both the item and category level related to between-person differences in memory, neural distinctiveness at the category level also tracked within-person variability in memory performance. Concurrently, neural distinctiveness at the item level was strongly associated with neural distinctiveness at the category level both within and across participants, elucidating a potential representational mechanism linking item- and category-level distinctiveness. In sum, we provide evidence that age-related neural dedifferentiation co-exists across multiple representational levels and is related to memory performance.Significance Statement Age-related memory decline has been associated with neural dedifferentiation, the finding that older adults have less distinctive neural representations than younger adults. This has been mostly shown for category information, while evidence for age differences in the specificity of item representations is meager. We used pattern similarity searchlight analyses to find indicators of neural dedifferentiation at both levels of representation (category and item) and linked distinctiveness to memory performance. Both item- and category-level dedifferentiation in the calcarine cortex were related to interindividual differences in memory performance, while category-level distinctiveness further tracked intraindividual variability. Crucially, neural distinctiveness was strongly tied between the item and category levels, indicating that intersecting representational properties of posterior occipital cortices reflect both individual exemplars and categories.

Do moments of inattention during study cause the error-speed effect for targets in recognition-memory tasks?

The error-speed effect - characterized by a decreased performance in a second recognition task for stimuli that elicited fast error responses in a first recognition task - has so far been predominantly interpreted as evidence for the existence of misleading memory information. However, this neglects a possible alternative explanation, namely that the effect may instead be caused by moments of inattention during study. Here, we introduce a manipulation that allowed us to distinguish between words from the study phase that participants most certainly paid attention to and those they did not. We hypothesized that if moments of inattention cause the error-speed effect, this effect should disappear when considering only targets that verifiably received attention during study. However, our results (N = 89) suggest that this is not the case: The error-speed effect still occurs for targets that participants attended to during study and thus indeed seems to be caused by misleading memory evidence rather than by moments of inattention during study.

A confidence framing effect: Flexible use of evidence in metacognitive monitoring

Human behavior is flexibly regulated by specific goals of cognitive tasks. One notable example is goal-directed modulation of metacognitive behavior, where logically equivalent decision-making problems can yield different patterns of introspective confidence depending on the frame in which they are presented. While this observation highlights the important heuristic nature of metacognitive monitoring, computational mechanisms underlying this phenomenon remain elusive. We confirmed the confidence framing effect in two-alternative dot-number discrimination and in previously published preference-choice data, demonstrating distinctive confidence patterns between "choose more" or "choose less" frames. Formal model comparisons revealed a simple confidence heuristic behind this phenomenon, which assigns greater weight to chosen than unchosen stimulus evidence. This computation appears to be based on internal evidence constituted under specific task demands rather than physical stimulus intensity itself, a view justified in terms of ecological rationality. These results shed light on the adaptive nature of human decision-making and metacognitive monitoring.

The effects of forewarning and divided attention on context retrieval in false recognition

After studying a list of words that are semantically associated to a critical lure, participants are more likely to attribute a falsely recognised critical lure to the context of its strong than weak semantic associates. This is known as the source-strength effect. The current study investigated the roles of automatic and controlled processing in context retrieval in false recognition that is demonstrated by the source-strength effect. The results revealed that the source-strength effect was impervious to forewarning (Experiment 1) and remained intact when attentional resources at encoding were reduced (Experiment 2), suggesting that context retrieval in false recognition is based on automatic processes that are not amenable to conscious control and do not require many attentional resources. This interpretation is consistent with the associative activation theory, which proposes that context retrieval in false recognition is based on memory associations between contexts and critical lures that are automatically created when critical lures become automatically activated via spreading activation process.

An Attentive Blank Stare Under Simulator-induced Spatial Disorientation Events

OBJECTIVE

This study investigated the effect of the spatial disorientation (SD) events on an attentive blank stare in the cockpit scene and demonstrated how much the flight task and visual delayed discrimination task were competing for the pilots' attention.

BACKGROUND

SD in flight is the leading cause of human error-related aircraft accidents in the military, general and commercial aviation, and has been an unsolved problem since the inception of flight. In-flight safety research, visually scanning cockpit instruments, and detecting changes are critical countermeasures against SD.

METHOD

Thirty male military pilots were performing a dual task involving piloting a flight simulator and visual change detection, while eye movements were obtained using an eye tracker.

RESULTS

Pilots made more flight errors and spent less time gazing at the area of change in SD-conflict than in non-conflict flights. The vestibular origin SD-conflict led not only to deteriorated piloting and visual scanning but also to problems coordinating overt and covert attention, resulting in lower noticeability of visual changes despite gazing at them.

CONCLUSION

Our study shows that looking at a given area in space is not a sufficient condition for effective covert attention allocation and the correct response to a visual stimulus. It seems to be important to make pilots aware of this during SD training.

APPLICATION

To reduce change blindness, some strategies, such as reducing the number of secondary tasks is extremely valuable. Particular efforts should also be focused on improving the design of the aircraft cockpit by increasing the conspicuousness of critical information.

The effect of chronic academic stress on intentional forgetting

This study investigated whether chronic academic stress could affect the directed forgetting (DF) process. Both the stress group (undergoing preparation for a major academic examination) and the control group performed a DF task. A forgetting cue was presented after a to-be-forgotten (TBF) word, whereas no cue appeared after a to-be-remembered (TBR) item in the study phase. An old/new recognition test was used in the test phase. The results showed that (1) the stress group showed a higher level of self-reported stress, state anxiety, negative affect, and decreased cortisol awakening response (CAR) compared with the control group, suggesting a higher level of stress for the stress group. (2) Both groups showed superior recognition performance of TBR than TBF items, suggesting a DF effect. (3) The stress group showed inferior recognition performance of TBF items and an enhanced DF effect compared with the control group. These results demonstrated that the intentional memory control process might be enhanced under chronic academic stress.

MRI evidence for material-specific encoding deficits and mesial-temporal alterations in presurgical frontal lobe epilepsy patients

OBJECTIVE

Neuroimaging studies reveal frontal lobe (FL) contributions to memory encoding. Accordingly, memory impairments are documented in frontal lobe epilepsy (FLE). Still, little is known about the structural or functional correlates of such impairments. Particularly, material specificity of functional changes in cerebral activity during memory encoding in FLE is unclear.

METHODS

We compared 24 FLE patients (15 right-sided) undergoing presurgical evaluation with 30 healthy controls on a memory fMRI-paradigm of learning scenes, faces, and words followed by an out-of-scanner recognition task as well as regarding their mesial temporal lobe (mTL) volumes. We also addressed effects of FLE lateralization and performance level (normal vs. low).

RESULTS

FLE patients had poorer memory performance and larger left hippocampal volumes than controls. Volume increase seemed, however, irrelevant or even dysfunctional for memory performance. Further, functional changes in FLE patients were right-sided for scenes and faces and bilateral for words. In detail, during face encoding, FLE patients had, regardless of their performance level, decreased mTL activation, while during scene and word encoding only low performing FLE patients had decreased mTL along with decreased FL activation. Intact verbal memory performance was associated with higher right frontal activation in FLE patients but not in controls.

SIGNIFICANCE

Pharmacoresistant FLE has a distinct functional and structural impact on the mTL. Effects vary with the encoded material and patients' performance levels. Thus, in addition to the direct effect of the FL, memory impairment in FLE is presumably to a large part due to functional mTL changes triggered by disrupted FL networks.

PLAIN LANGUAGE SUMMARY

Frontal lobe epilepsy (FLE) patients may suffer from memory impairment. Therefore, we asked patients to perform a memory task while their brain was scanned by MRI in order to investigate possible changes in brain activation during learning. FLE patients showed changes in brain activation during learning and also structural changes in the mesial temporal lobe, which is a brain region especially relevant for learning but not the origin of the seizures in FLE. We conclude that FLE leads to widespread changes that contribute to FLE patients' memory impairment.

Chanwuyi Lifestyle Medicine Program Improves Memory and Executive Functions of Older Adults With Mild Cognitive Impairment

The Chanwuyi Lifestyle Medicine Program (CLMP) was found to enhance the memory and executive functions of older adults with or without subjective memory complaints. The present study investigated whether similar beneficial effects can be extended to mild cognitive impairment (MCI). Twenty-four older adults with MCI were randomly assigned to receive the CLMP (the experimental group) or strategic memory training (SMT; the active control group) for 10 weeks. They were assessed by neuropsychological tests at baseline and post-intervention. Older adults showed similar visual and verbal memory improvements after receiving the CLMP and SMT. Yet, only those who received the CLMP showed distinct improvements in planning/organization, working memory, and attention in terms of accuracy, with greater cognitive gains associated with older age and lower levels of education and baseline cognitive functions. This study provides preliminary evidence for the effects of the CLMP on improving memory, attention, and executive functions in MCI.

Age differences in priming as a function of processing at encoding

It is unclear whether implicit memory (priming) is affected by aging. Some studies have reported no difference between young and older adults, while others have uncovered reliable reductions. An important factor that may explain these discrepancies is the manner of encoding. Processing requirements (perceptual/conceptual) have varied considerably between studies, yet processing abilities are not equally affected by aging. This study examined whether processing during encoding moderates age effects on priming. Young and older participants studied object-word pairs and made natural/manufactured (conceptual) and left/right rotation (perceptual) judgements in relation to the word or object. Objects served as targets on a subsequent continuous identification with recognition task to assess priming and recognition. Priming and recognition were greater in young than older adults for attended items, with a larger effect size in the conceptual than the perceptual condition. Findings suggest that age differences in priming may be a function of processing at encoding.

Examining the diagnostic value of the mnemonic discrimination task for classification of cognitive status and amyloid-beta burden

Alzheimer's disease (AD) is the most common type of dementia, characterized by early memory impairments and gradual worsening of daily functions. AD-related pathology, such as amyloid-beta (Aβ) plaques, begins to accumulate many years before the onset of clinical symptoms. Predicting risk for AD via related pathology is critical as the preclinical stage could serve as a therapeutic time window, allowing for early management of the disease and reducing health and economic costs. Current methods for detecting AD pathology, however, are often expensive and invasive, limiting wide and easy access to a clinical setting. A non-invasive, cost-efficient platform, such as computerized cognitive tests, could be potentially useful to identify at-risk individuals as early as possible. In this study, we examined the diagnostic value of an episodic memory task, the mnemonic discrimination task (MDT), for predicting risk of cognitive impairment or Aβ burden. We constructed a random forest classification algorithm, utilizing MDT performance metrics and various neuropsychological test scores as input features, and assessed model performance using area under the curve (AUC). Models based on MDT performance metrics achieved classification results with an AUC of 0.83 for cognitive status and an AUC of 0.64 for Aβ status. Our findings suggest that mnemonic discrimination function may be a useful predictor of progression to prodromal AD or increased risk of Aβ load, which could be a cost-efficient, noninvasive cognitive testing solution for potentially wide-scale assessment of AD pathological and cognitive risk.

Distinct age-related brain activity patterns in the prefrontal cortex when increasing cognitive load: A functional near-infrared spectroscopy study

Researchers have long observed distinct brain activity patterns in older adults compared with younger adults that correlate with cognitive performance. Mainly, older adults tend to show over-recruitment of bilateral brain regions during lower task loads and improved performance interpreted as compensation, but not observed at higher loads. However, there are discrepancies about whether increases in activity are compensatory and whether older adults can show compensation at higher loads. Our aim was to examine age-related differences in prefrontal cortex (PFC) activity and cognitive performance using functional near-infrared spectroscopy (fNIRS) during single and dual N-back tasks. Twenty-seven young adults (18-27 years) and 31 older adults (64-84 yrs) took part in the study. We used a robust fNIRS data methodology consisting of channel and region of interest analyses. Results showed differences in performance between task load conditions and age-related differences in reaction times but no age-group effects for accuracy. Older adults exhibited more bilateral PFC activation compared with young adults across all tasks and showed increases in brain activity in high compared to low load conditions. Our findings further support previous reports showing that older adults use compensatory recruitment of additional brain regions in PFC to maintain cognitive performance but go against the notion that such compensation is not present at higher cognitive loads. Additionally, our results indicate that fNIRS is a sensitive tool that can characterize adaptive cortical changes in healthy aging.

Null effects of temporal prediction on recognition memory but evidence for differential neural activity at encoding. A registered report

Previous research has demonstrated that rhythmic presentation of stimuli during encoding boosts subsequent recognition and is associated with distinct neural activity compared with when stimuli are presented in an arrhythmic manner. However, it is unclear whether the effect is driven by automatic entrainment to rhythm or non-rhythmic temporal prediction. This registered report presents an Electroencephalographic (EEG) study aimed at establishing the cognitive and neural mechanisms of the effect of temporal prediction on recognition. In a blocked design, stimulus onset during encoding was systematically manipulated in four conditions prior to recognition testing: rhythmic fixed (RF), rhythmic variable (RV), arrhythmic fixed (AF), and arrhythmic variable (AV). By orthogonally varying rhythm and temporal position we were able to assess their independent contributions to recognition enhancement. Our behavioural results did not replicate previous findings that show a difference in recognition memory based on temporal predictability at encoding. However, event-related potential (ERP) component analysis did show an early (N1) interaction effect of temporal position and rhythm, and later (N2 and Dm) effects driven by temporal position only. Taken together, we observed effects of temporal prediction at encoding, but these differences did not translate to later effects of memory, suggesting that effects of temporal prediction on recognition are less robust than previously thought.

Are multiple types of associative memory differently impacted by emotion?

The effect of emotion on associative memory is still an open question. Our aim was to test whether discrepant findings are due to differential impact of emotion on different types of associative memory or to differences in the way participants encoded stimuli across studies. We examined the effect of negative content on multiple forms of associative memory, using the same encoding task. Two registered experiments were conducted in parallel with random allocation of participants to experiments. Each experiment included 4 encoding blocks, in which participants read a neutral text comprised of 6 paragraphs, which were interleaved with neutral or negative images. Images were controlled for visual properties and semantic similarity. Memory tests included recognition memory, Remember/Know, order memory, temporal source memory and contextual memory. Analyses showed that emotion decreased contextual memory but not order memory or temporal source memory. We also found that temporal source memory and contextual memory were correlated. Recognition accuracy and subjective recollection were not impacted by emotion. In agreement with previous work, participants self-reported a reduced ability to integrate blocks containing negative images with paragraphs. In contrast to our hypothesis, results suggest that emotion does not impact all types of associative memory when stimuli are controlled.

Neuropsychological differential diagnosis of Alzheimer's disease and vascular dementia: a systematic review with meta-regressions

Introduction

Diagnostic classification systems and guidelines posit distinguishing patterns of impairment in Alzheimer's (AD) and vascular dementia (VaD). In our study, we aim to identify which diagnostic instruments distinguish them.

Methods

We searched PubMed and PsychInfo for empirical studies published until December 2020, which investigated differences in cognitive, behavioral, psychiatric, and functional measures in patients older than 64 years and reported information on VaD subtype, age, education, dementia severity, and proportion of women. We systematically reviewed these studies and conducted Bayesian hierarchical meta-regressions to quantify the evidence for differences using the Bayes factor (BF). The risk of bias was assessed using the Newcastle-Ottawa-Scale and funnel plots.

Results

We identified 122 studies with 17,850 AD and 5,247 VaD patients. Methodological limitations of the included studies are low comparability of patient groups and an untransparent patient selection process. In the digit span backward task, AD patients were nine times more probable (BF = 9.38) to outperform VaD patients (β g = 0.33, 95% ETI = 0.12, 0.52). In the phonemic fluency task, AD patients outperformed subcortical VaD (sVaD) patients (β g = 0.51, 95% ETI = 0.22, 0.77, BF = 42.36). VaD patients, in contrast, outperformed AD patients in verbal (β g = -0.61, 95% ETI = -0.97, -0.26, BF = 22.71) and visual (β g = -0.85, 95% ETI = -1.29, -0.32, BF = 13.67) delayed recall. We found the greatest difference in verbal memory, showing that sVaD patients outperform AD patients (β g = -0.64, 95% ETI = -0.88, -0.36, BF = 72.97). Finally, AD patients performed worse than sVaD patients in recognition memory tasks (β g = -0.76, 95% ETI = -1.26, -0.26, BF = 11.50).

Conclusion

Our findings show inferior performance of AD in episodic memory and superior performance in working memory. We found little support for other differences proposed by diagnostic systems and diagnostic guidelines. The utility of cognitive, behavioral, psychiatric, and functional measures in differential diagnosis is limited and should be complemented by other information. Finally, we identify research areas and avenues, which could significantly improve the diagnostic value of cognitive measures.

Do pictures influence memory and metamemory in Chinese vocabulary learning? Evidence from Russian and Colombian learners

Despite the increasing interest in learning non-alphabetical languages such as Chinese, research about its learning process for alphabet users is scarce. Research conducted on Latin alphabet users on learning languages written in Latin alphabet, or on Chinese language learning in Chinese native speakers, users is undoubtedly useful but it does not inform about the peculiarities of leaning Chinese language by other alphabet users. Additionally, several authors have highlighted the need to inform and extend the current second language acquisition theories on the particular challenges of learning a language that uses another script. In this research we aim to contribute filling this research gap and studied the learning process of Chinese vocabulary by users of scripts different from Chinese. In particular, we examined the role of pictures and translations as learning aids for Chinese language vocabulary learning in participants familiarized with either one or two alphabetical scripts (different from the Chinese logographic script). One hundred thirteen participants studied word-aid pairs in different conditions: Hanzi (Chinese in Chinese characters)-picture; Pinyin (Chinese in Latin alphabet)-picture; Hanzi-translation; Pinyin-translation. Participants evaluated the future recallability of the words and their meanings (i.e., judgements of learning) and completed two recognition tests. Words in Pinyin and words-translation pairs were judged to be easier to remember than Hanzi and word-pictures pairs. Participants remembered the meaning of words written in Hanzi better than in Pinyin, and word-translations pairs better than pictures, but they were more confident about word-picture pairs. These results suggest that pictures boost confidence in learning Chinese, but do not affect performance. These findings suggest that while pictures may boost confidence in learning Chinese, they may not necessarily lead to better performance. Our study provides valuable insights into the interaction of learning aids and writing system in (meta)memory during vocabulary acquisition.

Alternated emotional working memory in individuals with subclinical insomnia disorder: An electrophysiological study

The deleterious effects of sleep loss on sleep-dependent memory and emotional function have been documented in the current literature. Yet, the effects of insomnia-induced chronic sleep disturbance on emotional short-term memory have been scarcely investigated. Twenty-one participants with subclinical insomnia disorder (SID) and 20 healthy participants (healthy control, HC) performed a delayed recognition task of emotional faces, and event-related potentials (ERPs) involved in memory encoding, retention, and retrieval of faces across different emotional valences were assessed. Behavioral findings revealed that participants in the SID group had a larger response bias, being more likely to perceive negative faces as "old" faces presented in the retrieval phase than those in the HC group. ERP findings revealed that emotional faces in the SID vs. HC group induced significantly smaller P1 and late P3b and larger N170 amplitudes in the encoding phase and smaller negative slow wave (NSW) in the retention phase. In retrieval phase, the interaction between Sleep group and Valence were revealed for P1 and early P3b amplitudes, but no group differences were found after Bonferroni correction. These findings suggested that insomnia induced chronic sleep disturbance would influence performance on emotional working memory and induced processing phase specific regulation of neurophysiology in emotional working memory regardless of valence.

Memory error speed predicts subsequent accuracy for recognition misses but not false alarms

The current study aims to test whether faster recognition memory errors tend to result from stronger misleading retrieval, making them harder to correct in subsequent decisions than slower errors, and whether this pattern holds for both miss and false-alarm errors. We used a paradigm in which each single-item Old/New recognition decision was followed by a two-alternative forced-choice (2AFC) test between a target and a lure. Each 2AFC trial had one item that had just been tested for an Old/New judgment and one item that had not been previously tested. Across 183 participants, the RTs for single-item recognition errors were used to predict accuracy in the 2AFC test using a hierarchical logistic regression model. The results showed a relationship between error RT and subsequent 2AFC accuracy that was qualified by an interaction with error type. Slower miss responses were more likely to be corrected than faster misses, but no accuracy differences were observed between slower and faster false alarms. The implications of these findings are discussed as they relate to assumptions about memory processes underlying inaccurate retrieval, using the diffusion model and the two-high-threshold model as examples of accounts that explain errors in terms of misleading retrieval and failed retrieval, respectively.

The effect of visual perspective on episodic memory in aging: A virtual reality study

The possibility of flexibly retrieving our memories using a first-person or a third-person perspective (1PP or 3PP) has been extensively investigated in episodic memory research. Here, we used a Virtual Reality-based paradigm to manipulate the visual perspective used during the encoding stage to investigate age-related differences in the formation of memories experienced from 1PP vs. 3PP. 32 young adults and 32 seniors participated in the study. Participants navigated through two virtual cities to encode complex real-life virtual events, from either a 1PP (as if from their egocentric viewpoint) or a 3PP, while actively controlling an avatar. While recognition accuracy was higher in young adults after encoding in 1PP compared to 3PP, there was no benefit in memory formation in 1PP for older adults. These findings are discussed in terms of both age-related changes in episodic memory functioning and self-referencing processes.

Working memory and attention in choice

We study the role of attention and working memory in choices where options are presented sequentially rather than simultaneously. We build a model where a costly attention effort is chosen, which can vary over time. Evidence is accumulated proportionally to this effort and the utility of the reward. Crucially, the evidence accumulated decays over time. Optimal attention allocation maximizes expected utility from final choice; the optimal solution takes the decay into account, so attention is preferentially devoted to later times; but convexity of the flow attention cost prevents it from being concentrated near the end. We test this model with a choice experiment where participants observe sequentially two options. In our data the option presented first is, everything else being equal, significantly less likely to be chosen. This recency effect has a natural explanation with appropriate parameter values in our model of leaky evidence accumulation, where the decline is stronger for the option observed first. Analysis of choice, response time and brain imaging data provide support for the model. Working memory plays an essential role. The recency bias is stronger for participants with weaker performance in working memory tasks. Also activity in parietal areas, coding the stored value in working, declines over time as predicted.

Destination Memory for Self-Related Information: When I Tell Elvis Presley about My Favorite Food

Destination memory, the ability to remember to whom information was previously delivered, has found to be influenced by social processing and social interactions. This memory has also been shown to be compromised in normal aging. Our paper investigated whether older adults would demonstrate better destination memory for self-related information than for general information.

METHODS

We asked younger adults and older adults to tell self-related information (e.g., "I like Chinese food") and semantic information (e.g., "the moon is smaller than the sun") to pictures of celebrities (e.g., Elvis Presley).

RESULTS

Analysis showed higher destination memory for self-related information than for semantic information in older adults and younger adults.

DISCUSSION

Older adults may draw on self-related information to improve memory and social interactions.

False Memories in Individuals With Stabilized Schizophrenia

This study aimed to examine the false memories in individuals with stabilized schizophrenia. Using the Deese, Roediger, and McDermott (DRM) task, schizophrenia patients and matched healthy controls had to recall words from each DRM list. Following the presentation of the DRM lists, the participants performed a recognition task. Neuropsychological tests were also administered. Results demonstrated that patients with schizophrenia recalled and recognized significantly fewer studied words than the healthy participants. This failure in retrieval is likely to result from a lack of encoding strategies. Results also showed that a stabilized schizophrenic pathology neither increased nor reduced false memories. Patients and controls showed high levels of false memories. Signal detection analyses revealed that patients discarded the critical word as not having been studied, relying on a lax decision criterion (based on familiarity, best guess or chance). Although false memories fell within the normal range for both groups, in individuals with schizophrenia they probably result from deficient encoding processes. Nevertheless, correlational analyses did not show which cognitive deficits contribute to false memories in schizophrenia.

Conceptual relatedness promotes memory generalization at the cost of detailed recollection

An adaptive memory system is one that allows us to both retrieve detailed memories as well as generalize knowledge about our past, the latter termed memory generalization and is useful for making inferences about new situations. Research has indicated that memory generalization relies on forming knowledge structures by integrating experiences with shared encountered elements. Whether memory generalization occurs more readily when  experiences also have elements that share established (conceptual) information is less clear. It is also unclear if engaging in memory generalization during learning comes at the cost of retrieving detailed memories, the other function of episodic memory. To address these two knowledge gaps, we paired a modified version of the acquired equivalence task with a recognition memory test. Across three experiments, participants first learned a series of overlapping object-scene pairs (A-X, B-X and A-Y) in which half of the overlapping pairs contained conceptually-related objects (e.g., A-pencil; B-scissors; conceptual condition) and the other half contained unrelated objects (neutral condition). Participants ability to generalize to new overlapping object-scene pairs (B-Y) as well as not-learned but semantically-related objects was measured. Finally, participants completed a recognition memory test that included the encoded objects, perceptually similar lures or new foil objects. Across all experiments, we found higher rates of generalization but reduced detailed memory (indexed by increased false alarms to lure objects) for information learned in the conceptual than neutral condition. These results suggest the presence of conceptual knowledge biases an individual towards a generalization function of memory, which comes at the expense of detailed recollection.

Neuropragmatics: A scientometric review

Neuropragmatics investigates brain functions and neural activities responsible for pragmatic language abilities, often impaired in disorders such as hemisphere damage, autism, schizophrenia, and neurodegenerative disorders. This study examined the development of neuropragmatics and existing neuroimaging evidence using bibliometric and scientometric indicators, analyzing 4,247 documents published between 1967 and 2022 with CiteSpace and VOSviewer. Our cluster analysis revealed key themes. 1) Language comprehension loss due to brain injury: Studies exploring the impact of brain injuries on language comprehension and underlying neural mechanisms. 2) Right hemisphere damage and pragmatic language skills: Research focusing on the relationship between right hemisphere damage and pragmatic language abilities, investigating impairments in social language use and potential neural correlates. 3) Traumatic brain injury and social communication assessment: Research on traumatic brain injury effects on social communication skills, using various assessment tools to evaluate communication effectiveness in social situations. These clusters provide valuable insights into the neuropragmatics field and serve as a framework for future investigations. By building upon existing knowledge, researchers can improve our understanding of brain functions, language behavior, and enhance rehabilitation for individuals with pragmatic language impairments.

Not so different after all? An event-related potential study on item and source memory for object-scene pairs in German and Chinese young adults

In recent years, several cross-cultural studies reported that Westerners focus more on central aspects of a scene (e.g., an object) relative to peripheral aspects (e.g., the background), whereas Easterners more evenly allocate attention to central and peripheral aspects. In memory tasks, Easterners exhibit worse recognition for the central object when peripheral aspects are changed, whereas Westerners are less affected by peripheral changes. However, most of these studies rely on hit rates without correcting for response bias, whereas studies accounting for response bias failed to replicate cultural differences in memory tasks. In this event-related potential (ERP) study, we investigated item and source memory for semantically unrelated object-scene pairs in German and Chinese young adults using memory measures corrected for response bias (i.e., the discrimination index Pr). Both groups completed study-test cycles with either item memory tests or source memory tests. In item memory blocks, participants completed an old/new recognition test for the central object. Source memory blocks entailed an associative recognition test for the association between object and background. Item and source memory were better for intact than for recombined pairs. However, as verified with frequentist and Bayesian analyzes, this context effect was not modulated by culture. The ERP results revealed an old/new effect for the item memory task in both groups which was again not modulated by culture. Our findings suggest that cultural differences in young adults do not manifest in intentional memory tasks probing memory for object-scene pairs without semantic relations when using bias-corrected memory measures.

Mismatch negativity as a marker of auditory pattern separation

To what extent does incidental encoding of auditory stimuli influence subsequent episodic memory for the same stimuli? We examined whether the mismatch negativity (MMN), an event-related potential generated by auditory change detection, is correlated with participants' ability to discriminate those stimuli (i.e. targets) from highly similar lures and from dissimilar foils. We measured the MMN in 30 young adults (18-32 years, 18 females) using a passive auditory oddball task with standard and deviant 5-tone sequences differing in pitch contour. After exposure, all participants completed an incidental memory test for old targets, lures, and foils. As expected, participants at test exhibited high sensitivity in recognizing target items relative to foils and lower sensitivity in recognizing target items relative to lures. Notably, we found a significant correlation between MMN amplitude and lure discrimination, but not foil discrimination. Our investigation shows that our capacity to discriminate sensory inputs at encoding, as measured by the MMN, translates into precision in memory for those inputs.

Bayesian Adaptive Beamformer for Robust Electromagnetic Brain Imaging of Correlated Sources in High Spatial Resolution

Reconstructing complex brain source activity at a high spatiotemporal resolution from magnetoencephalography (MEG) or electroencephalography (EEG) remains a challenging problem. Adaptive beamformers are routinely deployed for this imaging domain using the sample data covariance. However adaptive beamformers have long been hindered by 1) high degree of correlation between multiple brain sources, and 2) interference and noise embedded in sensor measurements. This study develops a novel framework for minimum variance adaptive beamformers that uses a model data covariance learned from data using a sparse Bayesian learning algorithm (SBL-BF). The learned model data covariance effectively removes influence from correlated brain sources and is robust to noise and interference without the need for baseline measurements. A multiresolution framework for model data covariance computation and parallelization of the beamformer implementation enables efficient high-resolution reconstruction images. Results with both simulations and real datasets indicate that multiple highly correlated sources can be accurately reconstructed, and that interference and noise can be sufficiently suppressed. Reconstructions at 2-2.5mm resolution (  ∼  150K voxels) are possible with efficient run times of 1-3 minutes. This novel adaptive beamforming algorithm significantly outperforms the state-of-the-art benchmarks. Therefore, SBL-BF provides an effective framework for efficiently reconstructing multiple correlated brain sources with high resolution and robustness to interference and noise.

Dialect and gender perception in relation to the intelligibility of low-pass and high-pass filtered spontaneous speecha)

Most cues to speech intelligibility are within a narrow frequency range, with its upper limit not exceeding 4 kHz. It is still unclear whether speaker-related (indexical) information is available past this limit or how speaker characteristics are distributed at frequencies within and outside the intelligibility range. Using low-pass and high-pass filtering, we examined the perceptual salience of dialect and gender cues in both intelligible and unintelligible speech. Setting the upper frequency limit at 11 kHz, spontaneously produced unique utterances (n = 400) from 40 speakers were high-pass filtered with frequency cutoffs from 0.7 to 5.56 kHz and presented to listeners for dialect and gender identification and intelligibility evaluation. The same material and experimental procedures were used to probe perception of low-pass filtered and unmodified speech with cutoffs from 0.5 to 1.1 kHz. Applying statistical signal detection theory analyses, we found that cues to gender were well preserved at low and high frequencies and did not depend on intelligibility, and the redundancy of gender cues at higher frequencies reduced response bias. Cues to dialect were relatively strong at low and high frequencies; however, most were in intelligible speech, modulated by a differential intelligibility advantage of male and female speakers at low and high frequencies.

Does misremembering drive false alarms for emotional lures? A diffusion model investigation

Previous evidence has shown that, in a recognition memory task, emotion leads participants to make more false alarms and decreases response times (RTs) for false alarm responses. This pattern could arise because participants adopt more liberal responding for emotional stimuli and/or because emotional lures are more likely than neutral lures to produce misleading memory retrieval. Recently, Starns et al. designed a new recognition memory paradigm and found that the speed of memory errors shows the influence of misleading information resulting in unavoidable memory errors. This study investigates the basis of false alarms to emotional lures by testing predictions of the diffusion model for a recognition paradigm similar to that by Starns et al. Participants studied lists of emotional words and then completed an old-new recognition memory test. After each old-new decision, participants were asked to make a forced-choice recognition decision that provided a chance to correct possible errors on the preceding old-new decision. Under the assumption that emotion promotes misremembering, the diffusion model predicts that forced-choice accuracy should be lower for pairs with emotional versus neutral lures and that faster old-new errors should be associated with lower forced-choice accuracy. This study tested these predictions, providing theoretical insights into how emotion affects memory retrieval and further developing a new methodology for measuring recognition performance.

Reward association impairs recognition of incidentally encoded negative information: Electrophysiological evidence

Previous studies investigating the effect of reward on emotional episodic memory have produced inconsistent results. In this study, through two experiments using event-related potentials (ERPs), we investigated the effect of reward association on the encoding and retrieval of incidentally encoded emotional information, and examined whether this effect changes over time. Participants in the two experiments were asked to discriminate the emotional valence of color images under reward or no-reward condition and incidentally encode them. Immediate (in Experiment 1) or 24-hour delayed (in Experiment 2) recognition after encoding was tested. In Experiments 1 and 2, reward (relative to no-reward) significantly improved the recognition of positive and neutral items, but significantly reduced the recognition of negative items. During encoding, the significant ERP reward effects (significantly more positive ERP amplitude for rewarded items than for non-rewarded ones) for positive and neutral images were widely distributed from 200 to 1500 ms after image onset, while those for negative stimuli occurred mainly from 200 to 500 ms. During retrieval, the significant ERP reward effects for positive and neutral items occurred in the two experiments, but the reversed ERP reward effects for negative items were found only in Experiment 1. The results of the present study suggest that reward association affects the encoding and retrieval of emotional images by enhancing memory processing efficiency of positive and neutral items, while impairing recognition of negative items, thus yielding a robust and sustained modulation over frontal/frontocentral or centroparietal/parietal areas where mechanisms of reward and emotion processing operate in conjunction.

Memory in Social Interactions: The Effects of Introspection on Destination Memory in Traumatic Brain Injury

Destination memory, which is the ability to remember to whom one has sent information, is intimately associated with social cognition. We assessed whether processing attributes of destinations would improve destination memory in patients with traumatic brain injury (TBI). In this cross-sectional study, we tested the destination memory of 24 patients with TBI and 25 control participants in two conditions. On the first one (control condition), we invited participants to tell proverbs to celebrities' faces in order to decide, on a subsequent recognition test, whether they previously told that proverb to that celebrity or not. On the second condition (experimental introspection condition), the same procedures were repeated. However, after telling the proverbs, we invited participants to introspect about what the destination might believe about the proverbs (e.g., "What do you think that the celebrities would think about the proverbs?"). Group comparisons demonstrated better destination memory after the introspection than when no introspection was implemented in control participants, but there were no significant differences between the two conditions in patients with TBI. However, analyses of individual profiles demonstrated that more than half (n = 13) of the patients with TBI demonstrated better destination memory after introspection. While these results demonstrate a beneficial effect of introspection on destination memory for some cases of patients with TBI, more research is needed to reveal how introspection may influence patients' memory in social interactions.

Enhanced memory for central visual and auditory elements experienced during a stressful episode

Acute psychosocial stress has been shown to benefit memory for central visual elements of a stressful episode. Here, we aimed at investigating whether this effect is accompanied by improved visual memory for the committee members in a modified version of the Trier Social Stress Test (TSST). Specifically, we tested participants´ recognition memory for accessories located on the bodies of the committee members, as well as their faces. Moreover, we investigated how stress influences memories for the content of the verbal interactions. That is, we studied how well participants remembered factual information associated with the main stress source, like name, age, and position of the committee members, as well as how accurately they could recite the exact wording of phrases used by them. In a counterbalanced 2 × 2 design, 77 men and women took part either in a stressful or non-stressful version of the TSST. While stressed participants better remembered personal information about the committee members than non-stressed participants, no differences in memory for the correct wording of phrases could be observed. Furthermore, in line with our hypothesis, stressed participants better remembered central, but not peripheral visual stimuli, compared to non-stressed participants, while, contrary to our expectations, stress did neither affect memory for objects located on the bodies of the committee members nor their faces. Our results are in line with the theory of enhanced memory binding under stress and extend previous results regarding improved memory for central visual elements encoded under stress to auditory learning material associated with the stressor.

Age differences in neural distinctiveness during memory encoding, retrieval, and reinstatement

Robust evidence points to mnemonic deficits in older adults related to dedifferentiated, i.e. less distinct, neural responses during memory encoding. However, less is known about retrieval-related dedifferentiation and its role in age-related memory decline. In this study, younger and older adults were scanned both while incidentally learning face and house stimuli and while completing a surprise recognition memory test. Using pattern similarity searchlight analyses, we looked for indicators of neural dedifferentiation during encoding, retrieval, and encoding-retrieval reinstatement. Our findings revealed age-related reductions in neural distinctiveness during all memory phases in visual processing regions. Interindividual differences in retrieval- and reinstatement-related distinctiveness were strongly associated with distinctiveness during memory encoding. Both item- and category-level distinctiveness predicted trial-wise mnemonic outcomes. We further demonstrated that the degree of neural distinctiveness during encoding tracked interindividual variability in memory performance better than both retrieval- and reinstatement-related distinctiveness. All in all, we contribute to meager existing evidence for age-related neural dedifferentiation during memory retrieval. We show that neural distinctiveness during retrieval is likely tied to recapitulation of encoding-related perceptual and mnemonic processes.

Effects of nature-adapted lighting solutions ("Virtual Sky") on subjective and objective correlates of sleepiness, well-being, visual and cognitive performance at the workplace

Exposure to natural daylight benefits human well-being, alertness, circadian rhythms and sleep. Many workplaces have limited or no access to daylight. Thus, we implemented a light-panel ("Virtual Sky"), which reproduced nature-adapted light scenarios. In a laboratory office environment, three lighting scenarios were presented during the day: two lighting conditions with nature-adapted spectral light distributions, one with static and one with dynamic clouds, and a standard office lighting condition. We compared the impact of the three lighting scenarios on subjective and objective measures of alertness, cognitive performance, wellbeing, visual comfort, contrast sensitivity, and cortisol levels in 18 healthy young male volunteers in a within-participant cross-over study design. We found no evidence that an 8-h lighting scenario with static or dynamic clouds during the waking day (9am-5pm) was associated with any significant effect on objective and/or subjective alertness, cognitive performance and morning cortisol concentrations compared to standard workplace lighting. However, the dynamic light scenario was accompanied with lower levels of perceived tensionafter completing cognitive tasks and less effort to concentrate compared to the static lighting scenarios. Our findings suggest that apart from smaller effects on tension and concentration effort, nature-adapted lighting conditions did not improve daytime alertness and cognitive performance in healthy well-rested young participants, as compared to standard office lighting.

Recognition, remember-know, and confidence judgments: no evidence of cross-contamination here!

ABSTRACTWe report three experiments designed to reveal the mechanisms that underlie subjective experiences of recognition by examining effects of how those experiences are measured. Prior research has explored the potential influences of collecting metacognitive measures on memory performance. Building on this work, here we systematically evaluated whether cross-measure contamination occurs when remember-know (RK) and/or confidence (C) judgments are made after old/new recognition decisions. In Experiment 1, making either RK or C judgments did not significantly influence recognition relative to a standard no-judgment condition. In Experiment 2, making RK judgments in addition to C judgments did not significantly affect recognition or confidence. In Experiment 3, making C judgments in addition to RK judgments did not significantly affect recognition or patterns of RK responses. Cross-contamination was not apparent regardless of whether items were studied using a shallow or deep levels-of-processing task - a manipulation that yielded robust effects on recognition, RK judgments, and C. Our results indicate that under some conditions, participants can independently evaluate their recognition, subjective recognition experience, and confidence. Though contamination across measures of metamemory and memory is always possible, it may not be inevitable. This has implications for the mechanisms that underlie subjective experiences that accompany recognition judgments.