Brief, pre-learning stress reduces false memory production and enhances true memory selectively in females

Sex differences in eyewitness memory: A scoping review

Researchers in cognitive and forensic psychology have long been interested in the impact of individual differences on eyewitness memory. The sex of the eyewitness is one such factor, with a body of research spanning over 50 years that has sought to determine if and how eyewitness memory differs between males and females. This research has significant implications across the criminal justice system, particularly in the context of gendered issues such as sexual assault. However, the findings have been inconsistent, and there is still a lack of consensus across the literature. A scoping review and analysis of the literature was performed to examine the available evidence regarding whether sex differences in eyewitness memory exist, what explanations have been proposed for any differences found, and how this research has been conducted. Through a strategic search of seven databases, 22 relevant articles were found and reviewed. Results demonstrated that despite the mixed nature of the methodologies and findings, the research suggests that neither males nor females have superior performance in the total amount of accurate information reported, but rather that females may have better memory for person-related details while males may perform better for details related to the surrounding environment. There was also consistent evidence for the own-gender bias. There was some consensus that differences in selective attention between males and females may underlie these sex differences in eyewitness memory. However, none of the studies directly tested this suggested attentional factor, and thus future research is needed to investigate this using a more systematic and empirical approach.

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.

Relationship between COVID-related stressors and internalizing symptoms: Gendered neuroendocrine risk profiles

The COVID-19 pandemic generated significant life stress and increases in internalizing disorders. Moreover, COVID-related stressors disproportionately impacted women, consistent with outcomes showing a gender gap in stress-related disorders. Gender-related stress vulnerability emerges in adolescence alongside gender-specific changes in neuroendocrine signaling. Most research on the neuroendocrinology of stress-related disorders has focused on differences in the hypothalamic-pituitary-adrenal (HPA) axis effector hormone cortisol. More recent studies, however, emphasize dehydroepiandrosterone (DHEA), a neuroprotective and neuroactive hormone released concurrently with cortisol that balances its biobehavioral actions during stress. Notably, women show lower cortisol responses and higher DHEA responses to stress. However, lower cortisol and higher DHEA are associated with internalizing disorders in women, while those associations are opposite in men. Thus, gender-specific factors perhaps result in a neuroendocrine profile that places women at greater risk for stress-related disorders. The current study prospectively examined socially evaluated cold-pressor task (SECPT) induced neuroendocrine responses at age 15 and internalizing symptoms during the COVID-19 pandemic at age 21 in a cohort of 175 primarily Black low-socioeconomic status participants, while controlling for internalizing symptoms at age 15. The association between COVID-related stress and internalizing symptoms was not stronger in women. Lower DHEA-cortisol ratios were associated with a weaker relationship between COVID-related stress and internalizing symptoms in women, while higher ratios were associated with a weaker relationship in men. These findings suggest gender differences in the relationship between DHEA and cortisol and internalizing outcomes during a stressful period, and support differential neuroendocrine protective and risk pathways for young men and women.

A study of EEG non-stationarity on inducing false memory in different emotional states

False memory leads to inaccurate decisions and unnecessary challenges. Researchers have conventionally used electroencephalography (EEG) to study false memory under different emotional states. However, EEG non-stationarity has scarcely been investigated. To address this problem, this study utilized the nonlinear method of recursive quantitative analysis to analyze the non-stationarity of EEG signals. Deese-Roediger-McDermott paradigm experiments were used to induce false memory wherein semantic words were highly correlated. The EEG signals of 48 participants with false memory associated with different emotional states were collected. Recurrence rate (RR), determination rate (DET), and entropy recurrence (ENTR) data were generated to characterize EEG non-stationarity. Behavioral outcomes exhibited significantly higher false-memory rates in the positive group than in the negative group. The prefrontal, temporal, and parietal regions yielded significantly higher RR, DET, and ENTR values than other brain regions in the positive group. However, only the prefrontal region had significantly higher values than other brain regions in the negative group. Therefore, positive emotions enhance non-stationarity in brain regions associated with semantics compared with negative emotions, leading to a higher false-memory rate. This suggests that non-stationary alterations in brain regions under different emotional states are correlated with false memory.

Pre-Learning Stress That Is Temporally Removed from Acquisition Impairs Fear Learning

Few studies have examined the time-dependent effects of stress on fear learning. Previously, we found that stress immediately before fear conditioning enhanced fear learning. Here, we aimed to extend these findings by assessing the effects of stress 30 min prior to fear conditioning on fear learning and fear generalization. Two hundred and twenty-one healthy adults underwent stress (socially evaluated cold pressor test) or a control manipulation 30 min before completing differential fear conditioning in a fear-potentiated startle paradigm. One visual stimulus (CS+), but not another (CS-), was associated with an aversive airblast to the throat (US) during acquisition. The next day, participants were tested for their fear responses to the CS+, CS-, and several generalization stimuli. Stress impaired the acquisition of fear on Day 1 but had no significant impact on fear generalization. The stress-induced impairment of fear learning was particularly evident in participants who exhibited a robust cortisol response to the stressor. These findings are consistent with the notion that stress administered 30 min before learning impairs memory formation via corticosteroid-related mechanisms and may help us understand how fear memories are altered in stress-related psychological disorders.

Stress and memory encoding: What are the roles of the stress-encoding delay and stress relevance?

The effects of acute stress on memory encoding are complex. Recent work has suggested that both the delay between stress and encoding and the relevance of the information learned to the stressor may modulate the effects of stress on memory encoding, but the relative contribution of each of these two factors is unclear. Therefore, in the present study, we manipulated (1) acute stress, (2) the delay between stress and encoding, and (3) the relevance of the information learned to the stressor. The results indicated that stress during encoding led to better memory for study materials that were related to the stressor relative to memory for study materials that were unrelated to the stressor. This effect was numerically reduced for materials that were encoded 40 min after stressor onset (23 min after the stressor had ended) compared with items encoded at the time of the stressor, but this difference was not significant. These results suggest that the relevance of the information learned to the stressor may play a particularly important role in the effects of stress on memory encoding, which has important implications for theories of stress and memory.

The influence of positive emotion and negative emotion on false memory based on EEG signal analysis

Analyzing the influence of emotion on false memory through electroencephalogram is helpful to further explore the cognition function of brain. In this study, material emotion and participant emotion were introduced into Deese-Roediger-McDermott (DRM) paradigm experiment at the same time, which made the experiment process closer to real life. Different music was used to induce the emotion of 28 participants, and they were divided into positive group and negative group. Then, we analyzed the difference between the two groups from the behavior data, source location and cortex functional network of event related potential. The results of difference analysis show that the false memory rate of positive group (85 ± 8.6%) is significantly higher than that of negative group (72 ± 9.7%), and the activation degree and voxel number of the positive group are significantly higher than those of the negative group in the brain regions related to semantic coding (BA24 and BA45), and the compactness, the speed of information transmission and the small-world property of the brain network in positive group are significantly higher than those in negative group. The above results show that in the positive group, more brain resources are used for semantic association when they judge keywords, which confuse the keywords and learning words, and result in more false memories.

False recognitions in the DRM paradigm: the role of stress and warning

For the last decades, the factors increasing or decreasing the frequency of false memories have been of great interest. Some research also examined the effect of stress and warning on the true and false recognitions; however, so far most of the studies have yielded contradictory results or seems inadequate to understand the effect of these factors on false memory phenomenon. The purpose of this study is to examine the joint effects of stress and warning on the frequency of false and true memories elicited by the list-learning paradigm. The word lists derived from the Deese–Roediger–McDermott (DRM) paradigm were used in order to measure false and true recognition rates. Participants (N = 126) were exposed to either the Trier Social Stress Test (a stress condition) or a filler task at the beginning of the experiment (no-stress condition). Then, they were either subjected to a warning about false memories before DRM (pre-warning condition), subjected to a warning about false memories after DRM (post-warning condition), or given no warning at all (no-warning condition). Results showed that stress had a statistically significant effect on true recognition but not on false recognition. Furthermore, warning given after the DRM lists had a decreasing effect on the frequency of false memories. No significant interaction effect between stress and warning was found. Although our hypotheses were not confirmed, this study can contribute to the existing body of research by providing evidence that stress and warning have differential effects on both true and false memories derived from the DRM paradigm.

How does social competition affect true and false recognition?

Memory is highly susceptible to distortions, which can exert serious consequences in daily life. Despite this, we still know little about the role of factors that comprise social contexts in which memory processes occur. In the present study, we attempted to address this issue by examining how social competition influences true and false recognition. Participants performed a version of the Deese-Roediger-McDermott (DRM) paradigm designed to lure them into producing both true and false recognition either in competition against or independently of another person. We found that participants in the competition group showed lower levels of true and false recognition than those in the control group. Signal-detection analyses revealed that participants in both groups showed equivalent memory sensitivity for true recognition, while those in the competition group exhibited a decreased sensitivity for false recognition, which implies enhanced item-specific encoding during social competition. Moreover, participants in the competition group showed a more conservative response bias for both true and false recognition at retrieval than those in the control group, indicating a shift towards conservatism in decision strategy for both true and false recognition during social competition. The results provide compelling evidence for a decision-based reduction of true recognition and both encoding-based and decision-based reductions of false recognition under competitive contexts. Therefore, these novel findings may have implications both for understanding the powerful role of social competition on true and false memories and for understanding the potential role of social competition on other aspects of memory processes.

Memories of and influenced by the Trier Social Stress Test

Psychosocial stress influences cognition, affect and behavior. This current review summarizes the impact of acute stress on human long-term memory taking a neuroendocrine perspective. In this respect the stress associated increase in activity of the sympathetic nervous system (SNS) and the hypothalamus-pituitary-adrenal (HPA) axis are key. A special focus will be placed on findings obtained with the Trier Social Stress Test (TSST). This paradigm can be used to induce stress before or after a memory task. It was shown repeatedly that stress enhances long-term consolidation but impairs long term memory retrieval. However the TSST can also be used to assess memories of this stressful episode itself. The latter requires a standardized presentation of relevant stimuli during the TSST as well as a carefully designed control condition. Moreover special care has to be taken to control potential influences on visual exploration and working memory in order to correctly interpret observed effects on memory. The results obtained so far fit to the idea of enhanced encoding of salient information under stress. These findings are of relevance for educational, organizational and clinical applications.

Immediate pre-learning stress enhances baseline startle response and fear acquisition in a fear-potentiated startle paradigm

Extensive work has shown that stress time-dependently influences hippocampus-dependent learning and memory. In particular, stress that is administered immediately before learning enhances long-term memory, while stress that is temporally separated from learning impairs long-term memory. We have extended these findings by examining the impact of immediate, pre-learning stress on an amygdala-dependent fear conditioning task. One hundred and forty-one healthy participants underwent a stress (socially evaluated cold pressor test) or control manipulation immediately before completing differential fear conditioning in a fear-potentiated startle paradigm. Participants then completed extinction and extinction memory testing sessions 24 and 48 h later, respectively. Stress administered immediately before acquisition increased baseline startle responses and enhanced fear learning, as evidenced by greater fear-potentiated startle to the CS + . Although no group differences were observed during extinction training on Day 2, stressed participants exhibited evidence of impaired extinction processes on Day 3, an effect that was driven by group differences in acquisition. Importantly, stressed participants' cortisol responses to the stressor on Day 1 were positively associated with CS discrimination on Days 2 and 3. These findings suggest that stress immediately before fear conditioning strengthens fear memory formation and produces a more enduring fear memory, perhaps via corticosteroid activity. Such a paradigm could be useful for understanding factors that influence traumatic memory formation.

Memory instability as a gateway to generalization

Our present frequently resembles our past. Patterns of actions and events repeat throughout our lives like a motif. Identifying and exploiting these patterns are fundamental to many behaviours, from creating grammar to the application of skill across diverse situations. Such generalization may be dependent upon memory instability. Following their formation, memories are unstable and able to interact with one another, allowing, at least in principle, common features to be extracted. Exploiting these common features creates generalized knowledge that can be applied across varied circumstances. Memory instability explains many of the biological and behavioural conditions necessary for generalization and offers predictions for how generalization is produced.

Blunted cortisol response to acute pre-learning stress prevents misinformation effect in a forced confabulation paradigm

Research examining the effects of stress on false memory formation has been equivocal, partly because of the complex nature of stress-memory interactions. A major factor influencing stress effects on learning is the timing of stress relative to encoding. Previous work has shown that brief stressors administered immediately before learning enhance long-term memory. Thus, we predicted that brief stress immediately before learning would decrease participants' susceptibility to subsequent misinformation and reduce false memory formation. Eighty-four male and female participants submerged their hand in ice cold (stress) or warm (no stress) water for 3min. Immediately afterwards, they viewed an 8-min excerpt from the Disney movie Looking for Miracles. The next day, participants were interviewed and asked several questions about the video, some of which forced them to confabulate responses. Three days and three weeks later, respectively, participants completed a recognition test in the lab and a free recall test via email. Our results revealed a robust misinformation effect, overall, as participants falsely recognized a significant amount of information that they had confabulated during the interview as having occurred in the original video. Stress, overall, did not significantly influence this misinformation effect. However, the misinformation effect was completely absent in stressed participants who exhibited a blunted cortisol response to the stress, for both recognition and recall tests. The complete absence of a misinformation effect in non-responders may lend insight into the interactive roles of autonomic arousal and corticosteroid levels in false memory development.

ADRA2B deletion variant influences time-dependent effects of pre-learning stress on long-term memory

Extensive work over the past few decades has shown that certain genetic variations interact with life events to confer increased susceptibility for the development of psychological disorders. The deletion variant of the ADRA2B gene, which has been associated with enhanced emotional memory and heightened amygdala responses to emotional stimuli, might confer increased susceptibility for the development of post-traumatic stress disorder (PTSD) or related phenotypes by increasing the likelihood of traumatic memory formation. Thus, we examined whether this genetic variant would predict stress effects on learning and memory in a non-clinical sample. Two hundred and thirty-five individuals were exposed to the socially evaluated cold pressor test or a control condition immediately or 30min prior to learning a list of words that varied in emotional valence and arousal level. Participants' memory for the words was tested immediately (recall) and 24h after learning (recall and recognition), and saliva samples were collected to genotype participants for the ADRA2B deletion variant. Results showed that stress administered immediately before learning selectively enhanced long-term recall in deletion carriers. Stress administered 30min before learning impaired recognition memory in male deletion carriers, while enhancing recognition memory in female deletion carriers. These findings provide additional evidence to support the idea that ADRA2B deletion variant carriers retain a sensitized stress response system, which results in amplified effects of stress on learning and memory. The accumulating evidence regarding this genetic variant implicates it as a susceptibility factor for traumatic memory formation and PTSD-related phenotypes.

FKBP5 polymorphisms influence pre-learning stress-induced alterations of learning and memory

FK506 binding protein 51 (FKBP5) is a co-chaperone of heat shock protein 90 and significantly influences glucocorticoid receptor sensitivity. Single nucleotide polymorphisms (SNPs) in the FKBP5 gene are associated with altered hypothalamus-pituitary-adrenal (HPA) axis function, changes in the structure and function of several cognitive brain areas, and increased susceptibility to post-traumatic stress disorder, major depression, bipolar disorder and suicidal events. The mechanisms underlying these associations are largely unknown, but it has been speculated that the influence of these SNPs on emotional memory systems may play a role. In the present study, 112 participants were exposed to the socially evaluated cold pressor test (stress) or control (no stress) conditions immediately prior to learning a list of 42 words. Participant memory was assessed immediately after learning (free recall) and 24 h later (free recall and recognition). Participants provided a saliva sample that enabled the genotyping of three FKBP5 polymorphisms: rs1360780, rs3800373 and rs9296158. Results showed that stress impaired immediate recall in risk allele carriers. More importantly, stress enhanced long-term recall and recognition memory in non-carriers of the risk alleles, effects that were completely absent in risk allele carriers. Follow-up analyses revealed that memory performance was correlated with salivary cortisol levels in non-carriers, but not in carriers. These findings suggest that FKBP5 risk allele carriers may possess a sensitized stress response system, perhaps specifically for stress-induced changes in corticosteroid levels, which might aid our understanding of how SNPs in the FKBP5 gene confer increased risk for stress-related psychological disorders and their related phenotypes.

The contribution of trait negative affect and stress to recall for bodily states

How does trait negative affect shape somatic memory of stressful events? We hypothesized that negative affect would impair accurate recall of one's own heart rate during stressful situations. Two bio-behavioral studies used a new paradigm to test retrospective visceral perception and assessed whether negative affective states experienced during aversive events (i.e., the Trier Stress Task-Time 1) would retrospectively shape recall of past heart rate (Time 2), even when accounting for actual heart rate at the time of each stressful event (Time 1). Results across both studies showed that individual differences in negative affect in response to a stressful task predicted visceral recollections, and those who experienced more negative affect were more inaccurate. Negative affect was associated with a tendency to remember visceral reactions as worse than they actually were.

Memory under stress: from single systems to network changes

Stressful events have profound effects on learning and memory. These effects are mainly mediated by catecholamines and glucocorticoid hormones released from the adrenals during stressful encounters. It has been known for long that both catecholamines and glucocorticoids influence the functioning of the hippocampus, a critical hub for episodic memory. However, areas implicated in other forms of memory, such as the insula or the dorsal striatum, can be affected by stress as well. Beyond changes in single memory systems, acute stress triggers the reconfiguration of large scale neural networks which sets the stage for a shift from thoughtful, 'cognitive' control of learning and memory toward more reflexive, 'habitual' processes. Stress-related alterations in amygdala connectivity with the hippocampus, dorsal striatum, and prefrontal cortex seem to play a key role in this shift. The bias toward systems proficient in threat processing and the implementation of well-established routines may facilitate coping with an acute stressor. Overreliance on these reflexive systems or the inability to shift flexibly between them, however, may represent a risk factor for psychopathology in the long-run.

Arousal-But Not Valence-Reduces False Memories at Retrieval

Mood affects both memory accuracy and memory distortions. However, some aspects of this relation are still poorly understood: (1) whether valence and arousal equally affect false memory production, and (2) whether retrieval-related processes matter; the extant literature typically shows that mood influences memory performance when it is induced before encoding, leaving unsolved whether mood induced before retrieval also impacts memory. We examined how negative, positive, and neutral mood induced before retrieval affected inferential false memories and related subjective memory experiences. A recognition-memory paradigm for photographs depicting script-like events was employed. Results showed that individuals in both negative and positive moods–similar in arousal levels–correctly recognized more target events and endorsed fewer false memories (and these errors were linked to remember responses less frequently), compared to individuals in neutral mood. This suggests that arousal (but not valence) predicted memory performance; furthermore, we found that arousal ratings provided by participants were more adequate predictors of memory performance than their actual belonging to either positive, negative or neutral mood groups. These findings suggest that arousal has a primary role in affecting memory, and that mood exerts its power on true and false memory even when induced at retrieval.

Effects of post-encoding stress on performance in the DRM false memory paradigm

Numerous studies have investigated how stress impacts veridical memory, but how stress influences false memory formation remains poorly understood. In order to target memory consolidation specifically, a psychosocial stress (TSST) or control manipulation was administered following encoding of 15 neutral, semantically related word lists (DRM false memory task) and memory was tested 24 h later. Stress decreased recognition of studied words, while increasing false recognition of semantically related lure words. Moreover, while control subjects remembered true and false words equivalently, stressed subjects remembered more false than true words. These results suggest that stress supports gist memory formation in the DRM task, perhaps by hindering detail-specific processing in the hippocampus.

Stress time-dependently influences the acquisition and retrieval of unrelated information by producing a memory of its own

Stress induces several temporally guided “waves” of psychobiological responses that differentially influence learning and memory. One way to understand how the temporal dynamics of stress influence these cognitive processes is to consider stress, itself, as a learning experience that influences additional learning and memory. Indeed, research has shown that stress results in electrophysiological and biochemical activity that is remarkably similar to the activity observed as a result of learning. In this review, we will present the idea that when a stressful episode immediately precedes or follows learning, such learning is enhanced because the learned information becomes a part of the stress context and is tagged by the emotional memory being formed. In contrast, when a stressful episode is temporally separated from learning or is experienced prior to retrieval, such learning or memory is impaired because the learning or memory is experienced outside the context of the stress episode or subsequent to a saturation of synaptic plasticity, which renders the retrieval of information improbable. The temporal dynamics of emotional memory formation, along with the neurobiological correlates of the stress response, are discussed to support these hypotheses.

ADRA2B deletion variant selectively predicts stress-induced enhancement of long-term memory in females

Clarifying the mechanisms that underlie stress-induced alterations of learning and memory may lend important insight into susceptibility factors governing the development of stress-related psychological disorders, such as post-traumatic stress disorder (PTSD). Previous work has shown that carriers of the ADRA2B Glu(301)-Glu(303) deletion variant exhibit enhanced emotional memory, greater amygdala responses to emotional stimuli and greater intrusiveness of traumatic memories. We speculated that carriers of this deletion variant might also be more vulnerable to stress-induced enhancements of long-term memory, which would implicate the variant as a possible susceptibility factor for traumatic memory formation. One hundred and twenty participants (72 males, 48 females) submerged their hand in ice cold (stress) or warm (no stress) water for 3min. Immediately afterwards, they studied a list of 42 words varying in emotional valence and arousal and then completed an immediate free recall test. Twenty-four hours later, participants' memory for the word list was examined via free recall and recognition assessments. Stressed participants exhibiting greater heart rate responses to the stressor had enhanced recall on the 24-h assessment. Importantly, this enhancement was independent of the emotional nature of the learned information. In contrast to previous work, we did not observe a general enhancement of memory for emotional information in ADRA2B deletion carriers. However, stressed female ADRA2B deletion carriers, particularly those exhibiting greater heart rate responses to the stressor, did demonstrate greater recognition memory than all other groups. Collectively, these findings implicate autonomic mechanisms in the pre-learning stress-induced enhancement of long-term memory and suggest that the ADRA2B deletion variant may selectively predict stress effects on memory in females. Such findings lend important insight into the physiological mechanisms underlying stress effects on learning and their sex-dependent nature.

Decreased susceptibility to false memories from misinformation in hormonal contraception users

Sex hormones are increasingly implicated in memory formation. Recent literature has documented a relationship between hormones and emotional memory and sex differences, which are likely related to hormones, have long been demonstrated in a variety of mnemonic domains, including false memories. Hormonal contraception (HC), which alters sex hormones, has been associated with a bias towards gist memory and away from detailed memory in women who use it during an emotional memory task. Here, we investigated whether HC was associated with changes in susceptibility to false memories, which may be related to the formation of gist memories. We tested false memory susceptibility using two well-validated false memory paradigms: the Deese-Roediger-McDermott (DRM) task, and a story-based misinformation task. We found that hormonal contraceptive users were less susceptible to false memories compared to non-users in the misinformation task, and no differences were seen between groups on the DRM task. We hypothesise that the differences in false memories from the misinformation task may be related to hormonal contraceptive users' memory bias away from details, towards gist memory.