The role of eye fixation in memory enhancement under stress – An eye tracking study

Designing Novel Physiologic Monitor Displays for Combat Medics

INTRODUCTION

Combat medics who are responsible for the care of injured warfighters face challenges from their reliance on medical alarms that exceed the noise levels recommended by the WHO. This is because the elevated noise levels in military facilities, particularly from vehicular units and weaponry, compromise the combat medics' effectiveness and attentiveness to medical alarms. We previously designed a graphical ("configural") display to communicate patients' vital signs and found that when the configural display and traditional numerical display were concurrently presented to participants, it produced the fastest identification of patient vital signs and triggered the fewest number of alarms. This study used eye tracking to assess how participants direct visual attention to and engage with concurrently presented numerical and configural vital sign displays.

MATERIALS AND METHODS

We recruited 30 undergraduate students with normal hearing and vision for this study. Subjects were tasked with monitoring a simulated patient's vital signals using simultaneously presented numerical and configural vital sign displays. Concurrently, they performed an N-back task to simulate the multitasking required in a military environment. We manipulated the eccentricity and display position of the numerical and configural displays through 4 orientations, with each orientation being used in a monitoring block lasting 12 minutes. Continuous eye tracking was utilized to collect physiological data about participant display preference.

RESULTS

We used eye tracking to analyze several metrics: Total display viewing time, total viewing time percentage, number of dwells (groups of eye fixations), mean fixations per dwell, and fixation patterns during an emergency event. Participants spent more time looking at the configural display than the numerical display during nominal monitoring and emergency events. During emergencies, the percentage of time individuals spent looking at the configural display increased from 30 to 50%, while there was no corresponding increase in the participants' looking at the numerical display. When there were 2 concurrent emergency events instead of 1, total viewing time did not increase, suggesting that participants did not need to change their viewing strategy when the emergency situation complexity increased. Also, during emergencies, participants directed nearly half of their fixations to the configural display during the first 2 seconds of an emergency, while only directing fewer than 5% of fixations to the numerical display during that same period. The average response time for an emergency event was around 2 seconds, which suggests that participants obtained relevant information from the configural display in this time period.

CONCLUSIONS

We found that when a patient monitor contains both a configural display and a numerical display, participants look at the configural display. Furthermore, during time-sensitive situations, participants utilize the configural display to provide important information. We suggest this because the configural display integrates the relevant vital signs into one display. These findings provide justification for pursuing integrated vital sign displays to efficiently communicate patient conditions in complex environments. On the battlefield, swift decision-making is essential, as combat medics must minimize the time required to assess and act in critical situations.

The odour of an unfamiliar stressed or relaxed person affects dogs' responses to a cognitive bias test

Dogs can discriminate stressed from non-stressed human odour samples, but the effect on their cognition is unstudied. Using a cognitive bias task, we tested how human odours affect dogs' likelihood of approaching a food bowl placed at three ambiguous locations ("near-positive", "middle" and "near-negative") between trained "positive" (rewarded) and "negative" (unrewarded) locations. Using odour samples collected from three unfamiliar volunteers during stressful and relaxing activities, we tested eighteen dogs under three conditions: no odour, stress odour and relaxed odour, with the order of test odours counterbalanced across dogs. When exposed to stress odour during session three, dogs were significantly less likely to approach a bowl placed at one of the three ambiguous locations (near-negative) compared to no odour, indicating possible risk-reduction behaviours in response to the smell of human stress. Dogs' learning of trained positive and negative locations improved with repeated testing and was significant between sessions two and three only when exposed to stress odour during session three, suggesting odour influenced learning. This is the first study to show that without visual or auditory cues, olfactory cues of human stress may affect dogs' cognition and learning, which, if true, could have important consequences for dog welfare and working performance.

Representational formats of human memory traces

Neural representations are internal brain states that constitute the brain's model of the external world or some of its features. In the presence of sensory input, a representation may reflect various properties of this input. When perceptual information is no longer available, the brain can still activate representations of previously experienced episodes due to the formation of memory traces. In this review, we aim at characterizing the nature of neural memory representations and how they can be assessed with cognitive neuroscience methods, mainly focusing on neuroimaging. We discuss how multivariate analysis techniques such as representational similarity analysis (RSA) and deep neural networks (DNNs) can be leveraged to gain insights into the structure of neural representations and their different representational formats. We provide several examples of recent studies which demonstrate that we are able to not only measure memory representations using RSA but are also able to investigate their multiple formats using DNNs. We demonstrate that in addition to slow generalization during consolidation, memory representations are subject to semantization already during short-term memory, by revealing a shift from visual to semantic format. In addition to perceptual and conceptual formats, we describe the impact of affective evaluations as an additional dimension of episodic memories. Overall, these studies illustrate how the analysis of neural representations may help us gain a deeper understanding of the nature of human memory.

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.

Attenuation of visual exploration following stress

When we explore our surroundings, we frequently move our gaze to collect visual information. Studies have extensively examined gaze behavior in response to different visual scenes. Here, we examined how differences in an individual's state may affect visual exploration, for example, following acute stress. In this study, participants were exposed to either a psychosocial stressor-performing a public speaking task in front of a two-person committee-or a control condition absent stress induction. Elicitation of stress responses was validated using cortisol levels and subjective reports. Stress also led to an extended increase in pupil diameter (a proxy of arousal responses), suggesting it may also affect eye movements. Gaze behavior measures were taken prior and following the stress or control tasks. Acute stress attenuated visual exploration, reflected by fewer saccades and a smaller scanned area. Stress did not have a significant effect on either the tendency to look at social features or at salient regions of the images. These findings diverge from theoretical predictions suggesting that acute stress may facilitate social affiliative behaviors (e.g., Tend-and-Befriend theory). Reduced saccades and a smaller scanned area may be a possible mechanism explaining previous reports showing stress-related effects on various cognitive processes (e.g., visual working memory) that rely on visual exploration.

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.

Emotional memory in the lab: Using the Trier Social Stress Test to induce a sensory-rich and personally meaningful episodic experience

A myriad of clinical theories places emotional memory or mental representations at the root of mental disorders. Various cognitive-behavioural interventions are based on the assumption that targeting the underlying emotional memory is the working mechanism of treatment efficacy. To test the assumptions about the role of emotional memory in the development, maintenance, and treatment of mental disorders, we first need to establish ecologically valid paradigms that can induce emotional memory in the lab. For this, we used the Trier Social Stress Test (TSST), a standardized protocol to elicit social distress, paired with a neutral unfamiliar ambient odour, to create a sensory-rich and personally meaningful episodic experience. Seven days later, participants (N = 132) reactivated the memory of the TSST with the aid of auditory, olfactory, and visual retrieval cues, during which their heart rate and self-reported affective responses were collected. Although increases in heart rate were only observed during encoding, and not at retrieval, self-report ratings showed that cues which directly referred to the aversive experience evoked more negative valence, arousal, and feelings of lack of control during memory reactivation compared to control cues across sensory modalities. These findings are indicative of successful memory induction and corroborate the utility of ambient odours as retrieval aids. Moreover, the self-reported response to the reactivated emotional memory correlated with individual differences in indices of (social) anxiety and depression. Thereby, we provide preliminary evidence of the translational significance of this paradigm that offers potential for being a model to induce ecologically valid emotional memory in the lab.

Eye tracking metrics of orthopedic surgeons with different competency levels who practice simulation-based hip arthroscopic procedures

Objective

This study aimed to investigate the feasibility of using eye tracking data to identify orthopedic trainees' technical proficiency in hip arthroscopic procedures during simulation-based training.

Design

A cross sectional study.

Setting

A simulation-based training session for hip arthroscopy was conducted. Eye tracking devices were used to record participants' eye movements while performing simulated operations. The NASA Task Load Index survey was then used to measure subjective opinions on the perceived workload of the training. Statistical analyses were performed to determine the significance of the eye metrics and survey data.

Participants

A total of 12 arthroscopic trainees, including resident doctors, junior specialist surgeons, and consultant surgeons from the Department of Orthopedics in five hospitals, participated in this study. They were divided into three subgroups based on their prior clinical experience.

Results

Significant differences, including those for dwell time, number of fixations, number of saccades, saccade duration, peak velocity of the saccade, and pupil entropy, were observed among the three subgroups. Additionally, there were clear trends in the perceived workload of the simulation-based training based on feedback from the participants.

Conclusion

Based on this preliminary study, a correlation was identified between the eye tracking metrics and participants' experience levels. Hence, it is feasible to apply eye tracking data as a supplementary objective assessment tool to benchmark the technical proficiency of surgical trainees in hip arthroscopy, and enhance simulation-based training.

Gaze behavior in social interactions between beach volleyball players—An exploratory approach

Previous research has indicated that social interactions and gaze behavior analyses in a group setting could be essential tools in accomplishing group objectives. However, only a few studies have examined the impact of social interactions on group dynamics in team sports and their influence on team performance. This study aimed to investigate the effects of game performance pressure on the gaze behavior within social interactions between beach volleyball players during game-like situations. Therefore, 18 expert beach volleyball players conducted a high and a low game performance pressure condition while wearing an eye tracking system. The results indicate that higher game performance pressure leads to more and longer fixation on teammates’ faces. A higher need for communication without misunderstandings could explain this adaptation. The longer and more frequent look at the face could improve the receiving of verbal and non-verbal information of the teammate’s face. Further, players showed inter-individual strategies to cope with high game performance pressure regarding their gaze behavior, for example, increasing the number of fixations and the fixation duration on the teammate’s face. Thereby, this study opens a new avenue for research on social interaction and how it is influenced in/through sport.

Psychosocial stress induction in vivo vs. in virtuo and the influence of a health app on the acute stress reaction in youths: a study protocol for a randomized controlled trial

BACKGROUND

Acute and everyday stress is substantial for the development of mental and physical diseases, therefore it is crucial to get a better understanding of its pathogenesis. Different methods (e.g., Ambulatory Assessment) and stress reactivity paradigms (e.g., Trier Social Stress Test / TSST) in laboratory settings are often used to investigate basic mechanisms of this process. Due to the technological progress of the last years and especially due to children and adolescents growing up with it, the application of these developments in clinical research is reasonable. The aim of this project is to successfully transfer the TSST for children and adolescents into the virtual world, which will be compared to a real TSST situation. Physiological and psychological stress reactions will be analyzed in order to assess similarities and differences. Moreover, it will be investigated whether a Heart Coherence Exercise (HCE) has a stronger influence on coping with acute stress compared to Natural Relaxation (NR).

METHODS

This single-center experimental study will examine acute and everyday stress and coping processes in eighty-four healthy children and adolescents between the ages of 11 and 17. For everyday stress, different parameters (e.g., hormonal profiles and mood ratings) as well as a history of stressful life events and utilized coping methods will be recorded and a relaxation exercise will be practiced on a smartphone over 2 days. Regarding the acute stress reaction, the participants will be confronted either with the virtual or the real version of the TSST, followed by the trained relaxation exercise (HCE vs. NR). Physiological (e.g., cortisol and heart rate) and psychological stress markers (e.g., mood and gaze behavior) will be recorded continuously.

DISCUSSION

Studies are sparse using a virtual version of the TSST in children and adolescents. A successful virtual TSST would constitute an economical variant, which would also make it easier to administer it in clinical or population-based samples. Effective ambulatory relaxation exercises would be a useful addition to clinical treatment approaches.

TRIAL REGISTRATION

The study is registered in the German Clinical Trials Register since 10 August 2020 ( DRKS00022063 ).

A Model of Semantic Completion in Generative Episodic Memory

Many studies have suggested that episodic memory is a generative process, but most computational models adopt a storage view. In this article, we present a model of the generative aspects of episodic memory. It is based on the central hypothesis that the hippocampus stores and retrieves selected aspects of an episode as a memory trace, which is necessarily incomplete. At recall, the neocortex reasonably fills in the missing parts based on general semantic information in a process we call semantic completion. The model combines two neural network architectures known from machine learning, the vector-quantized variational autoencoder (VQ-VAE) and the pixel convolutional neural network (PixelCNN). As episodes, we use images of digits and fashion items (MNIST) augmented by different backgrounds representing context. The model is able to complete missing parts of a memory trace in a semantically plausible way up to the point where it can generate plausible images from scratch, and it generalizes well to images not trained on. Compression as well as semantic completion contribute to a strong reduction in memory requirements and robustness to noise. Finally, we also model an episodic memory experiment and can reproduce that semantically congruent contexts are always recalled better than incongruent ones, high attention levels improve memory accuracy in both cases, and contexts that are not remembered correctly are more often remembered semantically congruently than completely wrong. This model contributes to a deeper understanding of the interplay between episodic memory and semantic information in the generative process of recalling the past.

Inducing and Recording Acute Stress Responses on a Large Scale With the Digital Stress Test (DST): Development and Evaluation Study

Background

Valuable insights into the pathophysiology and consequences of acute psychosocial stress have been gained using standardized stress induction experiments. However, most protocols are limited to laboratory settings, are labor-intensive, and cannot be scaled to larger cohorts or transferred to daily life scenarios.

Objective

We aimed to provide a scalable digital tool that enables the standardized induction and recording of acute stress responses in outside-the-laboratory settings without any experimenter contact.

Methods

On the basis of well-described stress protocols, we developed the Digital Stress Test (DST) and evaluated its feasibility and stress induction potential in a large web-based study. A total of 284 participants completed either the DST (n=103; 52/103, 50.5% women; mean age 31.34, SD 9.48 years) or an adapted control version (n=181; 96/181, 53% women; mean age 31.51, SD 11.18 years) with their smartphones via a web application. We compared their affective responses using the international Positive and Negative Affect Schedule Short Form before and after stress induction. In addition, we assessed the participants’ stress-related feelings indicated in visual analogue scales before, during, and after the procedure, and further analyzed the implemented stress-inducing elements. Finally, we compared the DST participants’ stress reactivity with the results obtained in a classic stress test paradigm using data previously collected in 4 independent Trier Social Stress Test studies including 122 participants overall.

Results

Participants in the DST manifested significantly higher perceived stress indexes than the Control-DST participants at all measurements after the baseline (P<.001). Furthermore, the effect size of the increase in DST participants’ negative affect (d=0.427) lay within the range of effect sizes for the increase in negative affect in the previously conducted Trier Social Stress Test experiments (0.281-1.015).

Conclusions

We present evidence that a digital stress paradigm administered by smartphone can be used for standardized stress induction and multimodal data collection on a large scale. Further development of the DST prototype and a subsequent validation study including physiological markers are outlined.

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.

Split-Second Unlearning: Developing a Theory of Psychophysiological Dis-ease

Psychophysiological “stress” underpins many conditions including anxiety, depression, phobias, chronic fatigue syndrome and non-specific musculoskeletal pain such as fibromyalgia. In this article we develop an understanding of chronic psychophysiological stress from a psychological educational perspective, by drawing on supporting evidence that significant emotional events in early life (traumatic and benign) can influence health and well-being later in life. We suggest that traumatic events instigate psychophysiological “stress” responses and the formation of emotional memory images (EMIs) within very short time frames, i.e., “split-second learning.” Once formed these emotional memories are triggered in daily living “re-playing” psychophysiological stress responses, resulting in chronic psychophysiological “dis-ease.” We describe a novel therapeutic approach to scan clients for mannerisms signifying a subconscious “freeze-like” stress response that involves the client as a curious observer within their own experience, feeding back the non-verbal cues as they arrive in the moment. By breaking down the observable fragments of their split-second Pavlovian response to the trigger, clients can detach their EMI from the psychophysiology stress response, i.e., “split-second unlearning.” Our split-second unlearning model recognizes the EMI as a barrier to moving forward and needs to be unlearned before the client can become naturally adaptive again. We argue that this approach places the client at the center of the work without the need of getting bogged down in a life-long narrative.

The memory trace of a stressful episode

Stress influences episodic memory formation via noradrenaline and glucocorticoid effects on amygdala and hippocampus. A common finding is the improvement of memory for central aspects of a stressful episode. This is putatively related to changes in the neural representations of specific experiences, i.e., their memory traces. Here we show that the memory improvement for objects that were encountered in a stressful episode relates to differences in the neural representations of these objects in the amygdala. Using functional magnetic resonance imaging, we found that stress specifically altered the representations of central objects: compared to control objects, they became more similar to one another and more distinct from objects that were not part of this episode. Furthermore, higher similarity of central objects to the main stressor-the faces of the stress-inducing committee members-predicted better memory. This suggests that the central objects were closely integrated into a stressor-centered memory representation. Our findings provide mechanistic insights into how stress shapes the memory trace and have profound implications for neurocognitive models of stressful and emotional memory.

Gaze behavior is associated with the cortisol response to acute psychosocial stress in the virtual TSST

BACKGROUND

The Trier Social Stress Test (TSST) is a reliable tool for psychobiological stress induction. Because of its socio-evaluative nature, it has been useful for investigating gaze behavior. It has been shown that healthy people avoid looking toward faces when under stress, a finding that corroborates studies demonstrating avoidance of eye contact in social anxiety disorder. Yet, little is known about the relationship between gaze behavior and the biological stress response.

METHODS

In a final sample of 74 healthy males, a virtual reality version of the Trier Social Stress Test (TSST-VR) with an integrated eye tracker was implemented to investigate gaze behavior during acute stress induction. Stress response measures were collected via saliva samples and subjective stress ratings. Additional questionnaires were administered for examining the influence of social anxiety traits.

RESULTS

The TSST-VR elicited a significant psychobiological stress response. Overall, higher gaze times on judges compared to surroundings were found in the speech task while this pattern was reversed in the arithmetic task. Critically, there was a significant negative association between gaze time on judges and cortisol output in cortisol responders.

CONCLUSIONS

In a non-clinical sample, avoidance of gaze is associated with a stronger cortisol response to acute stress. This study demonstrates the potential of eye tracking to disentangle the effects of acute stress on social interaction, warranting further investigation in clinical populations characterized by high levels of anxiety in social situations, such as social anxiety and autism spectrum disorder.

Influence of Increasing Task Complexity and Use of Informational Assistance Systems on Mental Workload

(1) Background: Cognitive aspects and complexity in modern manual mixed model assembly are increasing. To reduce mental workload (MWL), informational assistance systems are introduced. The influence of complexity and used assistance system on MWL should be investigated to further improve the implementation of such assistance systems. (2) Methods: Using a simulated close to real-life assembly task a 2 × 3 design was chosen, with two levels of assembly complexity (within subjects) and three different assistance systems (paper, Augmented Reality (AR)-glasses, tablet-between subjects). MWL was measured using either physiological response (electrocardiogram (ECG) and eye-tracking) or performance indicators. (3) Results: An influence of task complexity on MWL can be shown. Additionally, usability based differences between the used assistance systems become more evident with reference to the results of area of interest analysis. (4) Conclusions: Using a multi-modal measurement approach, it is possible to detect complexity-based differences in MWL. Additional research on validity and alignment is needed to further use these for (neuro-) ergonomic considerations and recommendations.

Stress and cognition: A user's guide to designing and interpreting studies

Fueling the rapid growth in our understanding of how stress influences cognition, the number of studies examining the effects of stress on various cognitive processes has grown substantially over the last two decades. Despite this growth, few published guidelines exist for designing these studies, and divergent paradigm designs can diminish typical effects of stress or even reverse them. The goal of this review, therefore, is to survey necessary considerations (e.g., validating a stress induction), important considerations (e.g., specifying the timing of the stressor and cognitive task), and best practices (e.g., using Bayesian analyses) when designing a study that aims at least in part to examine the effects of acute stress on some cognitive process or function. These guidelines will also serve to help readers of these studies interpret what may otherwise be very confusing, anomalous results. Designing and interpreting studies with these considerations and practices in mind will help to move the field of stress and cognition forward by clarifying how, exactly, stress influences performance on a given cognitive task in a population of interest.

Prospective memory under acute stress: The role of (output) monitoring and ongoing-task demands

Prospective memory (PM) refers to the ability to postpone retrieval and execution of intended actions until the appropriate situation (PM cue) has come, while engaging in other ongoing activities or tasks. In everyday live we often perform PM tasks in stressful situations. While it has been shown that acute stress does not impair PM-cue identification and intention retrieval, little is known about acute stress effects on PM performance and memory for having performed an action (output monitoring) under varying ongoing-task demands. Here we investigated this in eighty healthy participants who performed event-based PM tasks during low- and high-demanding ongoing working memory tasks after having undergone either a standardized stress induction (Maastricht Acute Stress Test) or a standardized control protocol. Successful stress induction in the stress group compared to the no-stress group was confirmed by increased salivary cortisol, an indicator of stress-related hypothalamus-pituitaryadrenal axis activity, throughout the event-based PM tasks. Nevertheless, not-only PM-cue identification but also output monitoring remained fully intact after stress induction. The absence of these effects was independent of ongoing-task demands. Nonetheless, we replicated recent findings of a stress-induced reduction in performance cost of monitoring for PM-cue occurrences. Taken together our findings suggest that acute stress alters PM monitoring by enhancing selective attention, decreasing PM response thresholds or by shifting performance towards more automatic processes in PM, while not affecting PM-cue identification and output monitoring.

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.

Evaluation of emotional excitation during standardized endotracheal intubation in simulated conditions

Objective

To assess how stressful conditions in endotracheal intubation could induct emotional excitation in a population of acute care physicians.

Materials and methods

Two situations were randomly tested: one in standard and easy intubation conditions the other under difficult conditions presumed to induce stress (monitoring alarms, manikin lying on the floor, difficult intubation). Emotional excitation was assessed using several physiological (cardiac patterns, electrodermal activity and eye-tracking) and psycho-cognitive patterns. Auto-evaluations of video recordings and mental workload were performed immediately after simulation.

Results

Significant physiological parameter modifications were observed under the stressful intubation conditions (SDNN 35 ± 15 vs. 42 ± 21; p = 0.035—AVNN 514 ± 94 vs. 548 ± 110; p < 0.0001). Emotional excitation was demonstrated to lead a higher mental workload (NASA-TLX = 39 ± 18 vs. 63 ± 15; p = 0.001), frustration and effort dimensions being its determinant components (p < 0.01). Video recording auto-evaluations depicted significant emotional excitation occurrence under the difficult conditions, with few differences according to the operator’s experience.

Conclusion

This study highlights the fact that a stress condition during ETI on a simulation model leads to an important emotional excitation as compared to the neutral condition.

Memory for objects and startle responsivity in the immediate aftermath of exposure to the Trier Social Stress Test

Previously, we observed enhanced long-term memory for objects used (central objects) by committee members in the Trier Social Stress Test (TSST) on the next day. In addition, startle responsivity was increased. However, response specificity to an odour involved in the stressful episode was lacking and recognition memory for the odour was poor. In the current experiments, immediate effects of the stressor on memory and startle responsivity were investigated. We hypothesised memory for central objects of the stressful episode and startle response specificity to an odour ambient during the TSST to be enhanced shortly after it, in contrast to the control condition (friendly TSST). Further, memory for this odour was also assumed to be increased in the stress group. We tested 70 male (35) and female participants using the TSST involving objects and an ambient odour. After stress induction, a startle paradigm including olfactory and visual stimuli was conducted. Indeed, memory for central objects was significantly enhanced in immediate aftermath of the stressor. Startle responsivity increased at a trend level, particularly with regard to the odour involved in the stressful episode. Moreover, the stress group descriptively tended towards a better recognition of the odour involved. The study shows that stress enhances memory for central aspects of a stressful situation before consolidation processes come into play. In addition, results preliminarily suggest that the impact of stress on startle responsivity increases in strength but decreases in specificity during the first 24h after stress exposure.