The impact of cardiac perception on emotion experience and cognitive performance under mental stress

The association between interoception and olfactory affective responses

Odors are known to affect an individual's emotions and physiological states. Recent research has revealed that olfaction is linked to the mental representation of internal sensations, known as interoception. However, little research has examined how interoception relates to emotional responses to odors. This research aimed to fill this gap in the literature. We conducted two studies with a total of 548 Japanese women (n = 500 and n = 48 in Studies 1 and 2, respectively). Study 1 used an online survey to assess the relationship between self-reported interoceptive traits and the intensity of positive emotions in response to daily odors. Study 2 examined how self-reported interoceptive traits modulated the arousal ratings of odors presented in the laboratory and the concordance between these perceived arousal ratings and odor-evoked physiological responses. Study 1 confirmed that self-reported interoceptive traits were significant predictors of positive emotional intensity of odors. In Study 2, individuals with high interoceptive measure scores showed concordance between their perceived emotional arousal and the physiological responses associated with that emotion, whereas individuals with low scores did not. These findings suggest that how people perceive their internal sensations contributes to shaping their olfactory affective experiences, thereby broadening the scope of interoception research and aromachology. The practical implications of these findings for the development of commercial fragrances are discussed.

Evaluating the Effects of Different Cognitive Tasks on Autonomic Nervous System Responses: Implementation of a High-Precision, Low-Cost Complementary Method

INTRODUCTION

We developed a low-cost, user-friendly complementary research tool to evaluate autonomic nervous system (ANS) activity at varying levels of cognitive workload. This was achieved using visual stimuli as cognitive tasks, administered through a specially designed computer-based test battery.

METHODS

To assess sympathetic stress responses, skin conductance response (SCR) was measured, and electrocardiograms (ECG) were recorded to evaluate heart rate variability (HRV), an indicator of cardiac vagal tone. Twenty-five healthy adults participated in the study. SCR and ECG recordings were made during both tonic and phasic phases using a computer-based system designed for visual stimuli. Participants performed a button-pressing task upon seeing the target stimulus, and the relationship between reaction time (RT) and cognitive load was evaluated.

RESULTS

Analysis of the data showed higher skin conductance levels (SCLs) during tasks compared to baseline, indicating successful elicitation of sympathetic responses. RTs differed significantly between simple and cognitive tasks, increasing with mental load. Additionally, significant changes in vagally mediated HRV parameters during tasks compared to baseline highlighted the impact of cognitive load on the parasympathetic branch of the ANS, thereby influencing the brain-heart connection.

CONCLUSION

Our findings indicate that the developed research tool can successfully induce cognitive load, significantly affecting SCL, RTs, and HRV. This validates the tool's effectiveness in evaluating ANS responses to cognitive tasks.

Interoceptive accuracy does not predict emotion perception in daily life

Peripheral emotion theories suggest a crucial role of interoception for emotion perception, which in turn facilitates emotion regulation. Laboratory studies found positive relations between interoceptive accuracy and perceived emotion intensity and arousal. Studies in natural settings are largely missing, but seem important by virtue of emotional experience and regulation diversity.

On hundred seven participants underwent a cardiovascular interoceptive accuracy task. Afterwards, participants provided detailed information on perceived emotions and emotion regulation strategies in an ecological momentary assessment (EMA). Multilevel models were calculated. In consideration of valence, emotion intensity, arousal, intensity of body sensations and, emotion regulation success were modeled as a function of centered interoceptive accuracy.

Interoceptive accuracy did not predict any emotion perception criterion. Lower accuracy was related to a slightly stronger decrease of perceived arousal after regulation.

Differences in emotion categories, intensity, and sample collection might explain divergences to laboratory studies.

Attention-Dependent Physiological Correlates in Sleep-Deprived Young Healthy Humans

Cognitive functions could be specifically altered but masked from the unspecific effect of workload, a common factor affecting cognitive functions that modulate peripheral outputs. To identify workload-related and specific, task-dependent components, physiological correlates of cognitive functioning were derived by studying 15 healthy volunteers performing attentional tasks in baseline and post-sleep-deprivation conditions (one week interval). Sleep deprivation was introduced to increase workload. We performed recordings of heart pulse, facial temperature, and head movements during tasks assessing attentional network efficiency (ANT, Attentional Network Task; CCT, Continuous Compensatory Tracker) workload assessments after execution of tasks. Changes in cognitive and physiological indices were studied in both conditions; physiological correlates of cognitive performance were identified by correlating changes from baseline to post-sleep-deprivation condition of task indices with those of physiological measures after correction for between-conditions workload changes. We found that mental and physical demands of workload increased after sleep deprivation. We identified no changes in cognitive and physiological indices across conditions; specific physiological correlates of attentional systems, as indicated by the negative correlation between changes in ANT-alerting and changes in amplitude of head movements and the positive correlation between changes in CCT-speed indexing alertness and changes in facial temperature.

Autonomic Nervous System Reactivity During Speech Repetition Tasks: Heart Rate Variability and Skin Conductance

Cognitive and emotional challenges may elicit a physiological stress response that can include arousal of the sympathetic nervous system (fight or flight response) and withdrawal of the parasympathetic nervous system (responsible for recovery and rest). This article reviews studies that have used measures of electrodermal activity (skin conductance) and heart rate variability (HRV) to index sympathetic and parasympathetic activity during auditory tasks. In addition, the authors present results from a new study with normal-hearing listeners examining the effects of speaking rate on changes in skin conductance and high-frequency HRV (HF-HRV). Sentence repetition accuracy for normal and fast speaking rates was measured in noise using signal to noise ratios that were adjusted to approximate 80% accuracy (+3 dB fast rate; 0 dB normal rate) while monitoring skin conductance and HF-HRV activity. A significant increase in skin conductance level (reflecting sympathetic nervous system arousal) and a decrease in HF-HRV (reflecting parasympathetic nervous system withdrawal) were observed with an increase in speaking rate indicating sensitivity of both measures to increased task demand. Changes in psychophysiological reactivity with increased auditory task demand may reflect differences in listening effort, but other person-related factors such as motivation and stress may also play a role. Further research is needed to understand how psychophysiological activity during listening tasks is influenced by the acoustic characteristics of stimuli, task demands, and by the characteristics and emotional responses of the individual.

Using Simulation to Implement an OR Cardiac Arrest Crisis Checklist

Crisis checklists are cognitive aids used to coordinate care during critical events. Simulation training is a method to validate process improvement initiatives such as checklist implementation. In response to concerns staff members expressed regarding their comfort level when responding to infrequent occurrences such as cardiac arrest and other OR emergencies, the OR Comprehensive Unit-based Safety Program team at our facility decided to institute the use of crisis checklists in the OR during critical events. We provided 90-minute education sessions, simulation opportunities, and debriefings to help staff members become more comfortable using these checklists. Based on program evaluations, 80% of staff members who participated in the training expressed an increased comfort level when caring for a patient in cardiac arrest.

Improvement of Interoceptive Processes after an 8-Week Body Scan Intervention

Objective: Interoceptive processes are defined as ability to detect sensations arising within the body. There is a growing body of research investigating ways of improving interoceptive processes. One promising approach increasing the attention to bodily sensations is the body scan (BS), a method stemming from mindfulness-based stress reduction. Research so far revealed only heterogenous findings of meditational practice and mindfulness-based stress reduction on interoceptive processes. Even more importantly, there is no study considering the effect of an 8-week BS intervention on interoceptive processes and the distinguishable subdomains of interoception. Therefore, the main objective of this research is to examine the effects of a BS intervention on different interoceptive subdomains over 8 weeks of training in two different samples.

Methods: In study 1, healthy participants executed a 20 min standardized audiotaped BS in the BS intervention group (n = 25) each day over 8 weeks. The control group (n = 24) listened to an audio book for the same amount of time. In study 2, the BS group (n = 18) was compared to an inactive control group (n = 18). In both studies, three measurement points were realized and interoceptive accuracy (IAc) – using a heartbeat perception task – as well as interoceptive sensibility (IS) – using confidence ratings for the heartbeat perception task and the subscale ‘interoceptive awareness’ of the Eating Disorder Inventory-2 (EDI-2) – were assessed.

Results: In study 1, we found, as a descriptive trend, IAc and confidence ratings to be increased irrespective of the condition. However, post hoc analysis revealed a significant improvement of IAc between T1 and T3 in the BS intervention only. IS revealed to be unaffected by the interventions. In study 2, we observed a significant positive effect of the BS intervention on IAc and confidence ratings compared to the inactive controls. As in study 1, IS (EDI-2) was unaffected by the intervention.

Discussion: The results highlight the fact that interoception can be improved by long-term interventions focusing on bodily signals. Further studies might focus on clinical samples showing deficits in interoceptive processes and could use other bodily systems for measurement (e.g., respiratory signals) as well methods manipulating body ownership.