Contribution of Time Estimation and Knowledge to Heartbeat Counting Task Performance under Original and Adapted Instructions

Body detachment in response to emotions: Evidence from a rubber hand illusion study in adolescent patients with non-suicidal self-injurious behavior and dissociative symptoms

Previous studies have proposed a connection between dissociation and the sense of body ownership, and initial evidence suggests that emotions could modulate this relationship. Here we aimed to investigate how differently arousing emotions influence the malleability of the bodily self. This study included 50 adolescent psychiatric patients with non-suicidal self-injurious behavior (NSSI)-who were divided into low-dissociation and high-dissociation groups-along with 25 healthy controls. Participants completed six trials of the rubber hand illusion while listening to neutral, sad, or fearful vocalizations. Heart rate, skin conductance level, and non-specific skin conductance responses were concomitantly measured. After each trial, participants completed the rubber hand illusion questionnaire as a subjective illusion measure, and acute dissociation, mood, and proprioceptive drift were assessed. Overall, the NSSI high-dissociation group reported the highest subjective illusion under all conditions. Additionally, fearful vocalizations resulted in a stronger subjective illusion than the neutral condition in the NSSI low-dissociation group, but not in the NSSI high-dissociation and healthy control groups. The NSSI low-dissociation group showed a higher proprioceptive drift than the NSSI high-dissociation group. Moreover, acute dissociation was positively related to subjective illusion, but not related to proprioceptive drift. In conclusion, body detachment in response to emotions may be responsible for the malleability of the sense of body ownership. This finding highlights the need for clinical interventions to stabilize self-experiences during emotional situations, especially in patients with dissociative symptoms.

Association between individual differences in interoception and cardiac coherence during heart rate variability biofeedback

Heart rate variability biofeedback (HRVBF) is the training to increase vagally-mediated heart rate variability (vmHRV), accompanied by slow-paced breathing and feedback of heart rhythm. It has been reported to be effective for emotion and cognition. In recent years, increased attention has turned toward participant characteristics as factors affecting HRVBF training effects. Focusing on neural basis commonalities between the mechanisms of HRVBF training effects and processing interoception, this study comprehensively measured interoception and examined the relationship between interoception and cardiac coherence reflecting HRVBF effects. Fifty-four healthy young participants were recruited, and subjective interoception was measured using the Japanese version of Multidimensional Assessment of Interoceptive Awareness (MAIA-J) and the Japanese version of the Body Perception Questionnaire-Body Awareness Very Short Form (BPQ-BAVSF-J), objective interoception using heartbeat counting task (HCT), heart rate variability (HRV), visual exteroception, and the coherence score achieved by HRVBF. We conducted a multiple regression analysis with interoception, HRV, and visual exteroception parameters as explanatory variables and the coherence score as the objective variable. Some subjective interoception and HRV parameters were found to be associated with the coherence score. Our results were consistent with previous studies, showing that higher vmHRV was related to high cardiac coherence. Interoception effects on cardiac coherence may be limited because of the low adjusted coefficient of determination and less selected explanatory variables in the multiple regression analysis. Our results may contribute toward predicting HRVBF training effects and the screening of those who are likely to benefit from the training from the perspective of interoception and vmHRV.

Validity Concerns About the Heartbeat Counting Task Extend to Alcohol Use disorder: Evidence From Subclinical and Clinical Samples

Theoretical models propose that interoception plays a role in addictive disorder. However, this assumption has been mostly tested using the heartbeat counting task (HCT), which is known to be contaminated by estimation strategies. An adapted version of the HCT (in which respondents report only felt heartbeats) has been developed to reduce estimation biases. Here, we examined the validity of the classical and adapted HCT versions in samples presenting alcohol use disorders. We recruited a clinical sample of 48 patients with severe alcohol use disorder (SAUD), matched with 41 healthy controls (HC), and a subclinical sample of 32 binge drinkers (BD), matched with 30 HC. Participants performed the classical HCT, adapted HCT, and a time estimation task. We additionally assessed mental health variables theoretically related to interoception (alexithymia, anxiety, childhood trauma, depression and emotion regulation). In all groups, HCT scores were smaller in adapted than classical HCT. Patients with SAUD, but not BD, showed lower HCT scores than matched controls, independently of the task. We found no correlation between HCT scores and psychological constructs. Heartbeats reported during classical HCT correlated with seconds reported during time estimation task for SAUD and matched HC, suggesting the use of time estimation strategies to perform the task. The largely reduced HCT performance in the adapted version, the association between HCT performance and time estimation performance and the lack of theoretically expected associations between HCT scores and psychological variables extend doubts on the validity of these tasks for measuring interoceptive accuracy in problematic alcohol consumption.

Predicting fluctuations in cardiac interoceptive accuracy and sensibility through additional heart rate variability reductions in everyday life

Cardiac interoception, assessed in terms of accuracy (IAcc) and sensibility (IS; beside others), is important for health and wellbeing. Ecological momentary assessment studies exploring the dynamics of cardiac interoception showed substantial fluctuations of IAcc and IS in everyday life. States of increased (physiologically indicated) stress, such as decreased heart rate variability (HRV), may hamper interoceptive skills, while more relaxed states (higher HRV) seem to go along with increased IAcc. We built on this and investigated if higher (physiological) stress indicated via HRV reductions independent of metabolic needs (i.e., additional HRV reduction, AddHRVr) could (differentially) predict IAcc and IS, respectively. In an initial sample of 119 participants, with data of (up to) three consecutive days, we simulated the predictive value of AddHRVr. We found that AddHRVr before an ambulatory cardiac interoception task predicted poor IAcc and higher IS. We replicated this pattern of findings in an independent sample of 66 participants. Both studies provide first insights into the dynamics of IAcc and IS in daily life, which seems to differ when following AddHRVr. This lays the groundwork for just in time adaptive interventions (JITAIs) supporting individuals in states of high vulnerability and promoting cardiac interoceptive skills.

Under the surface: Low cardiac vagal tone and poor interoception in young adults with subclinical depressive symptoms

INTRODUCTION

Depressive symptoms are associated with alterations in central and autonomic nervous system activity, including misperception of bodily activity (e.g., low interoception), somatic symptoms and decreased vagally mediated heart rate variability (vmHRV). However, there is a lack of studies that examine both perception of bodily activity and autonomic function in depression. The present study investigated the association between interoception, vmHRV, and subclinical depressive symptoms.

METHOD

Eighty-eight students were enrolled and vmHRV was calculated from a 5-minute resting electrocardiogram. Interoceptive accuracy (heartbeat tracking task; heartbeat discrimination task), interoceptive sensibility (Body Perception Questionnaire), and depressive symptoms (Depression, Anxiety and Stress Scale - 21 Items) were assessed.

RESULTS

Interoceptive accuracy and sensibility positively correlated with vmHRV and negatively correlates with depressive symptoms. Cluster analysis performed on vmHRV, interoceptive accuracy, and sensibility provided two clusters: the first characterized by a pattern of low interoceptive accuracy, sensibility, and decreased resting vmHRV, the second characterized by an opposite pattern. Regression analyses showed that the first cluster was characterized by significantly higher depressive symptoms compared to the second (β = 1.97; pBonferroni = 0.04), even after controlling for sex, BMI, anxiety, and stress levels.

CONCLUSIONS

Subclinical depressive symptoms are associated with a consistent impairment in the perception and interpretation of bodily activity and altered regulatory function of the autonomic nervous system. The present results suggest that the alteration of brain-body communication could be involved in subclinical depressive symptoms. Early identification of such alterations could help with targeted preventive strategies.

Having the Heart to Exercise Control: Cardiac Interoception Influences Self-Paced Exercise Regulation

The aim of this study was to examine the role of cardiac interoception on self-regulated (Experiment 1) and externally prescribed (Experiment 2) exercises. Cardiac interoception was assessed using heartbeat tracking and discrimination tasks in both experiments. Based on heartbeat discrimination performance, participants were partitioned into groups demonstrating GOOD and POOR cardiac interoceptive accuracy. In Experiment 1, 20 participants completed two self-regulated 20-min cycling tasks at two intensities (light rated physical exertion [RPE on Borg Scale = 10] vs. hard-to-very hard, RPE = 16). During self-regulated exercise, the POOR cardiac interoception group showed lower differences in their exercise work rates and physiological responses between light and hard-to-very hard intensity exercises. These differences were partly attributable to a higher work rate over the first 5 min of light intensity exercise and a higher initial rate of work in the first min of hard-to-very hard intensity exercise. In Experiment 2, 15 participants completed an externally prescribed, constant-load cycling task performed at 80% of the peak power output, to task failure. During externally prescribed exercise, GOOD and POOR groups did not differ in their time-to-task failure nor in their physiological and perceptual responses to the exercise. Together these findings demonstrate that individual differences in interoceptive accuracy influence the regulation of self-paced exercise but do not affect externally prescribed exercise tolerance under constant load.

No gender difference in cardiac interoceptive accuracy: Potential psychophysiological contributors in heartbeat counting task

Gender differences in interoceptive awareness-awareness of internal bodily signals such as heartbeat perception-have been suggested, with some findings indicating behaviourally reduced but subjectively enhanced awareness in women, though these findings are still contentious. This study aimed to comprehensively examine gender differences in three aspects of interoceptive awareness: behavioural accuracy, subjective confidence, and relationship between them (i.e., metacognition). We used a modified heartbeat counting task that prohibited estimation strategies and increased the number of trials up to 20. Using data from 74 healthy young adults (39 women and 35 men), we evaluated gender differences and practice effects for each measure via Bayesian linear mixed models, controlling for individual heart rate and trial duration on a trial-by-trial basis. Contrary to previous research, the results revealed no reduced interoceptive accuracy in women; instead, higher interoceptive accuracy score was associated with shorter trial durations and lower heart rates regardless of gender. Moreover, women exhibited underconfidence about their performance, and therefore lower metacognition scores, compared to men. Trial repetitions moderated women's lowered metacognition but did not affect accuracy or confidence. These findings highlight potential physiological and psychological confounding factors in the heartbeat counting task, such as heart rate and reporting style, and emphasise several cautions for studying gender differences in interoceptive awareness.

Women with premenstrual syndrome exhibit high interoceptive accuracy, but low awareness, with parasympathetic rebound responses from stress

Premenstrual syndrome (PMS) is characterized by emotional or physical discomfort that occurs specifically during the luteal phase. However, women with PMS typically do not exhibit abnormalities in serum sex hormone levels or structural anomalies, making it challenging to identify distinct pathological findings unique to PMS. Instead, they may exhibit hypersensitivity to fluctuations in sex hormone levels within the normal range. This study involved experiments conducted in the late luteal phase. The pre-stress baseline state evaluated the effects of PMS on interoception using the Heartbeat Counting Task (HCT) and the Multidimensional Assessment of Interoceptive Awareness (MAIA), and the effects on emotional states using a questionnaire assessing subjective emotions in the late luteal phase. The results indicated that the "PMS group" scored higher on the HCT compared to the "without PMS group," while their MAIA scores were lower. Additionally, the PMS group reported experiencing more negative and stressful states. The findings suggest that women with PMS demonstrate high accuracy in but lower awareness of interoception. This mismatch between "accuracy" and "awareness" may indicate a maladaptive state regarding mental health. The stress-related analysis examined whether the effects of stress on exacerbating PMS include impacts on interoception and the autonomic nervous system (ANS). States before baseline, immediately after, and during stress recovery were evaluated. The results revealed that women in the PMS group exhibited more pronounced negative and stressful states; they showed higher scores on the HCT, with scores progressively increasing as the task was repeated. Regarding ANS indices, no main effect of group was observed, but parasympathetic activity increased during the recovery period compared to the pre-stress baseline. In the degree of changes in parasympathetic activity from the baseline to post-stress and recovery periods, a group-by-time interaction effect was observed. These findings suggest that the PMS group may experience a prolonged rebound effect during the recovery phase following induced stress. In conclusion, women with PMS exhibit a discrepancy between high interoceptive accuracy and low awareness of their sensations. This may contribute to heightened discomfort and suggest that vulnerability to stress, mediated by the parasympathetic nervous system, exacerbates factor for PMS symptoms.

Discrepancies in the Definition and Measurement of Human Interoception: A Comprehensive Discussion and Suggested Ways Forward

Interoception has been the subject of renewed interest over the past 2 decades. The involvement of interoception in a variety of fundamental human abilities (e.g., decision-making and emotional regulation) has led to the hypothesis that interoception is a central transdiagnostic process that causes and maintains mental disorders and physical diseases. However, interoception has been inconsistently defined and conceptualized. In the first part of this article, we argue that the widespread practice of defining interoception as the processing of signals originating from within the body and limiting it to specific physiological pathways (lamina I spinothalamic afferents) is problematic. This is because, in humans, the processing of internal states is underpinned by other physiological pathways generally assigned to the somatosensory system. In the second part, we explain that the consensual dimensions of interoception are empirically detached from existing measures, the latter of which capture loosely related phenomena. This is detrimental to the replicability of findings across measures and the validity of interpretations. In the general discussion, we discuss the main insights of the current analysis and suggest a more refined way to define interoception in humans and conceptualize its underlying dimensions.

Exploring Individual Differences in Interoception Among Athletes Based on a Three-Dimensional Construct of Interoception

Previous studies demonstrated that sensorimotor training enhances interoceptive abilities. Athletes are highly engaged in performance-driven physical training and often incorporate-to varying degrees-sensorimotor training into their routines. In this study, we investigated the role of individual differences in interoception by comparing professional athletes of different performance levels and both sexes with recreational athletes and controls, applying a three-dimensional model of interoception. Twenty-six elite athletes, 52 recreational athletes, and 50 college students were recruited from national sports teams, local sports training centers, and local universities. We used the Multidimensional Assessment of Interoperative Awareness (MAIA), the Heartbeat Detecting Task (HDT), and a numeric rating scale based on HDT to measure interoceptive sensibility, accuracy, and awareness. At average, athletes showed significantly higher interoceptive sensibility, interoceptive accuracy, and interoceptive awareness than controls. Elite athletes reported significantly higher scores in all measures of interception compared to recreational athletes. Intriguingly, Non-Distracting for interoceptive sensibility was positively correlated with the level of experience in elite athletes. Male athletes had better interoceptive sensibility and interoceptive awareness compared to female athletes in the elite group, while no significant sex differences were detected in the other two groups. These results indicated that level of sport experience and sex are associated with differences in interoceptive accuracy, interoceptive sensibility, and interoceptive awareness. It also suggests that interoceptive ability is possibly an experience-dependent trait for athletic performance, which provides insight for improving sports performance through an approach of enhancing interoceptive ability.

I can feel my heartbeat: The relationship between interoceptive abilities and emotional states during stress and recovery in healthy adolescents

The goal of the current study was to investigate the differential effects of three interoception dimensions on psychophysiological stress responses (reactivity and recovery) in adolescents. A total of 102 adolescents (Mage = 14.10 years, SDage = 0.63; 50 males) completed the heartbeat counting task with adapted instructions to assess interoceptive accuracy, sensibility, and awareness. During a follow-up session, participants underwent a standardized stressful task, throughout which measures of negative affect and respiratory sinus arrythmia (RSA) were collected. Results from multilevel models indicated that adolescents with higher interoceptive accuracy reported less pronounced increases in negative affect during stress induction, and subsequently experienced a less steep decrease in negative affect during recovery, compared to those with lower accuracy. Regarding RSA, adolescents with higher interoceptive accuracy exhibited greater decreases in RSA from baseline to stress, while those with higher interoceptive awareness maintained higher RSA levels throughout the experiment. In contrast, individuals with higher interoceptive sensibility exhibited lower levels of RSA during the experiment. These findings add to the limited literature on interoception in adolescents by illuminating its role in emotional experiences, stress responses, and recovery processes. Our study suggests that examining distinct dimensions of interoception, along with physiological measures during stress and recovery, is crucial for understanding its beneficial or adverse effects in adolescence. The complexity and potential significance of interoceptive dimensions extend beyond their correlations with traditional self-report measures, warranting further investigation to clarify their implications and underlying mechanisms.

Interoception, emotion regulation strategies and skin-picking behaviors - Results of an intensive longitudinal study

Compulsive skin-picking is associated with emotion regulation difficulties, whose origins remain unclear. Interoception, plays an important role in effective emotion regulation. This study examined the relationship between interoception, emotion regulation strategies, and skin-picking in 136 individuals (85% women, aged 18-41), including 71 engaging in skin-picking and 65 psychologically healthy controls. We were interested in between-group differences in maladaptive and adaptive emotion regulation and aspects of interoception as well as associations of the latter with skin-picking symptoms and use of emotion regulation strategies. At baseline, we assessed habitual emotion regulation strategies (rumination, suppression, distraction, engagement, arousal control, reappraisal) and Interoceptive Sensibility (e.g., emotional awareness, body listening, self-regulation, noticing) through self-report questionnaires. Moreover, Interoceptive Accuracy (IAc) was measured via a Heartbeat Counting Task. Additionally, Ecological Momentary Assessment (EMA) over seven days was used to register use of emotion regulation strategies and the occurrence and severity of skin-picking episodes during that period. At baseline, the skin-picking group exhibited lower IAc, emotional awareness, and higher habitual use of rumination than control group. Lower IAc was associated with higher odds of reporting skin-picking episodes assessed during EMA. Body listening correlated with a reduced sense of control over skin-picking during EMA. In total sample, self-regulation was related to lower odds of using rumination during EMA and noticing with less use of cognitive reappraisal. The study highlights the complex relationship between interoception, emotion regulation, and skin-picking, offering new insights into the mechanisms underlying skin picking disorder.

Exploring sex differences in cardiac interoceptive accuracy using the phase adjustment task

Previous evidence suggests males and females differ with respect to interoception-the processing of internal bodily signals-with males typically outperforming females on tasks of interoceptive accuracy. However, interpretation of existing evidence in the cardiac domain is hindered by the limitations of existing tools. In this investigation, we pooled data from several samples to examine sex differences in cardiac interoceptive accuracy on the phase adjustment task, a new measure that overcomes several limitations of the existing tools. In a sample of 266 individuals, we observed that females outperformed males, indicative of better cardiac interoceptive accuracy, but had lower confidence than males. These results held after controlling for sex differences in demographic, physiological and engagement factors. Importantly, these results were specific to the measure of cardiac interoceptive accuracy. No sex differences were observed for individuals who completed the structurally identical screener task, although a similar pattern of results was observed in relation to confidence. These surprising data suggest the presence of a female advantage for cardiac interoceptive accuracy and potential differences in interoceptive awareness (metacognition). Possible reasons for mixed results in the literature, as well as implications for theory and future research, are discussed.

Relationship of interoceptive accuracy in acne vulgaris patients: A prospective, controlled study

Acne vulgaris (AV) is a chronic inflammatory skin condition predominantly observed during adolescence. Interoception accuracy (IAc) refers to the ability to perceive internal bodily states such as hunger and thirst. Since the brain and skin originate from the same embryological layer, the ectoderm, it is hypothesized that skin changes and disorders might affect individual perceptions. The purpose of this study is to evaluate the relationship between IAc and AV. This study included 94 AV patients and 94 sex- and age-matched healthy controls. The participants completed the Beck Depression Inventory (BDI), Beck Anxiety Inventory (BAI), Dermatology Life Quality Index (DLQI), and heartbeat perception task to assess IAc. The severity of acne was assessed using the Global Acne Grading System (GAGS). Acne patients had lower IAc scores than controls did (P = 0.026). Severe depression or anxiety symptoms were associated with lower IAc scores (P = 0.027, P = 0.046). Acne severity did not significantly affect IAc scores. There was a weak negative connection between the DLQI score and IAc (r = -0.208, P = 0.022), suggesting that lower quality of life is correlated with reduced IAc. Gender significantly influenced IAc. As a result, individuals with acne may have a reduced capacity to accurately perceive internal bodily states, potentially impacting overall well-being. Enhancing interoception might positively contribute to AV treatment and management.

Exploring the relationship between cardiac awareness and balance

Postural balance requires the interplay between several physiological signals. Indirect evidence suggests that the perception of signals arising from the autonomic nervous system might play a role (e.g. cardiac awareness). Here, we tested this hypothesis by investigating the relationship between postural control and cardiac awareness (i.e. interoception) in a sample of N = 70 healthy individuals. Postural control was measured using a medical robotic device, while cardiac awareness was evaluated using the heartbeat counting task. A within-subject design included two platform configurations (static, unstable) and two visual feedback conditions (eyes open, eyes closed). For each condition, we measured the sway area and the range of oscillation of the platform, as well as the range of oscillation and the quantity of movement of participants' trunk. In the "platform unstable, eyes closed" condition, participants with higher cardiac awareness demonstrated a significantly smaller sway area and reduced oscillations of both the platform and their trunk. These findings hint at a potential link between interoception and postural control, suggesting that the perception of internal body signals might sustain balance.

Linking the inner and outer mental representations of the body to social cognition skills: A systematic review and meta-analysis

An interesting interpretation of embodiment highlights the critical role of mental body representations (BR), including motor, somatosensory, and interoceptive formats, for social cognition. However, the nature of this relationship is still debated at the empirical level, with various studies arriving at different conclusions. Here, we present a systematic review and meta-analysis aimed to summarize data from 3466 participants in 21 studies to provide a more comprehensive understanding of the relationship between inner and outer BR and social cognition. We focused on two core social cognition aspects: empathy and Theory of Mind (ToM). Concerning the inner BR, our meta-analytic findings reveal a significant correlation between specific interoceptive dimensions (i.e., interoceptive sensibility and accuracy) and social cognition, which was stronger for empathy than ToM. Conversely, although further research is needed, functional BR that mainly involve the outer body processing (i.e., nonaction-oriented BR) may show positive links with ToM. These findings point to specific interactions between BR and social cognition skills, supporting multi-faceted and embodied social cognition models. However, we also identified critical knowledge gaps and highlighted the need for further investigation to deepen our theoretical understanding of these relationships and their implications for clinical practice.

WACARDIA: Graphical MATLAB software for Wireless Assessment of CARDiac Interoceptive Accuracy

Many theories of psychological function emphasize the importance of bodily sensations and the ability to accurately detect them, known as interoceptive accuracy. The most common measure of interoceptive accuracy uses heartbeat detection tasks such as the Whitehead Task, yet to our knowledge there are no freely accessible programs to conduct this task. In this paper, we present novel software called WACARDIA (Wireless Assessment of CARDiac Interoceptive Accuracy), which is free, open-source software that conducts the heartbeat detection task using Matlab and Psychtoolbox. WACARDIA contains several key features supporting participant engagement, operator convenience, and measurement accuracy. First, the program includes an optional practice trial of unlimited duration, a participant-facing graphical interface, and the ability to perform heartbeat detection training. Second, the operator is provided with a graphical user interface, live trial feedback, an accurate wireless electrocardiogram device, and a separate program to conduct the related Heartbeat Tracking task. Finally, the program ensures the accuracy of collected data by scheduling the delivery of tones with high precision and implementing fail-safes to automatically reset erroneous measurements. This paper includes flowcharts that help create transparency by describing our algorithm. We also outline customizable aspects of the program with the intent to have WACARDIA's algorithm expanded to accommodate more situations and applications. With this paper, we hope to encourage the practice of publicizing research software to contribute to the transparency, rigor, and reproducibility of scientific studies. WACARDIA and video tutorials are available at www.github.com/iankleckner/wacardia and http://wacardia.iankleckner.com.

He Who Seeks Finds (Bodily Signals): German Validation of the Interoceptive Attention Scale (IATS) and its Relationship with Subclinical Psychopathology

Alterations in interoception have been linked to psychopathology. Recent findings suggest that both the attention to and the accuracy of, interoceptive perceptions may be oppositely related to subclinical symptomatology. Thus, providing well-validated tools that tap into these interoceptive processes is crucial for understanding the relation between interoceptive processing and subclinical psychopathology. In the current study (N = 642), we aimed to (1) validate the German version of the Interoceptive Attention Scale (IATS; Gabriele et al., 2022), and (2) test the differential association of self-reported interoceptive attention and accuracy with subclinical symptomatology, including alexithymia, depressive, and anxious symptomatology. We observed that a one-factor solution is a well-fitting model for the IATS. Further, the IATS showed good internal consistency, convergent, and divergent validity, but poor test-retest reliability. Self-reported interoceptive attention and accuracy were unrelated to each other. However, IATS scores were positively related to all measures of psychopathology (except depressive symptomatology), whereas self-reported interoceptive accuracy scores showed negative or nonsignificant relations with these. Our data suggest that the IATS is a good instrument to measure self-report interoceptive attention in the German population. Further, we highlight the need to distinguish between constructs of interoception to better understand the relation between interoception and psychopathology.

Extreme weight conditions impact on the relationship between risky decision-making and interoception

Anorexia nervosa (AN) and obesity (OB) lie on the two ends of the broad spectrum of extreme weight conditions (EWC). Both disorders entail the constant risk to one's body integrity. Importantly, risk-taking is supported by internal signals, the perception of which is typically distorted in EWC. In this study, we sought to characterize in EWC: (i) risky decision-making by contrasting situations in which people process bodies or neutral objects and (ii) the relationship between interoceptive ability and risky decision-making. In a between-subject design, participants with AN restricting type, participants with class 2 OB, and two groups of matched healthy controls (HC) (total N = 160) were administered either the Balloon Analogue Risk Task (BART) or a modified version of it by using a body-related stimulus as a cue in the place of the balloon. Moreover, we collected a measure of interoceptive sensibility and a measure of interoceptive accuracy. Results showed that, when analysing the global population as a continuum based on the BMI, the risk propensity decreased as a function of increased BMI, only for the task involving a body-related stimulus. Moreover, while HC risk propensity toward a body-related stimulus correlated with interoceptive sensibility, such correlation was absent in participants with AN. Individuals with OB, on the opposite pole, showed mixed interaction between interoception and risky decision-making in both tasks. These findings add one more tile to understanding these complex pathologies in the EWC spectrum, opening up future differential rehabilitation scenarios.

The body mirroring thought: The relationship between thought transitions and fluctuations in autonomic nervous activity mediated by interoception

Our thought states change without intention. This study verified that the transition of thought states varies with fluctuations in autonomic nervous activity, and that this effect is modulated by interoceptive accuracy. The participants completed the heartbeat counting task (HCT) and vigilance task. We assessed the participants' interoceptive accuracy based on their performance on the HCT. The vigilance task is a simple attention task, and during this task, we asked the participants to report the content and contemplation of their thoughts. Consequently, participants with accurate interoception were more likely to remain in a highly contemplative thought state when parasympathetic activity was suppressed. In contrast, the dominance of parasympathetic activity facilitated transitions to different thought states or experiences of less contemplative thought states in them. The results suggest that even subtle changes in bodily responses at rest can affect thought transitions in people with accurate interoception.

Intranasal Oxytocin Improves Interoceptive Accuracy and Heartbeat-Evoked Potentials During a Cardiac Interoceptive Task

BACKGROUND

Interoception represents perception of the internal bodily state, which is closely associated with social/emotional processing and physical health in humans. Understanding the mechanism that underlies interoceptive processing, particularly its modulation, is therefore of great importance. Given the overlap between oxytocinergic pathways and interoceptive signaling substrates in both peripheral visceral organs and the brain, intranasal oxytocin administration is a promising approach for modulating interoceptive processing.

METHODS

Using a double-blind, placebo-controlled, between-participant design, we recruited 72 healthy male participants who performed a cardiac interoceptive task during electroencephalograph and electrocardiograph recording to examine whether intranasal administration of the neuropeptide oxytocin could modulate interoceptive processing. We also collected data in a resting state to examine whether we could replicate previous findings.

RESULTS

The results showed that in the interoceptive task, oxytocin increased interoceptive accuracy at the behavioral level, which was paralleled by larger heartbeat-evoked potential amplitudes in frontocentral and central regions on the neural level. However, there were no significant effects of oxytocin on electroencephalograph or electrocardiograph during resting state.

CONCLUSIONS

These findings suggest that oxytocin may only have a facilitatory effect on interoceptive processing under task-based conditions. Our findings not only provide new insights into the modulation of interoceptive processing via targeting the oxytocinergic system but also provide proof-of-concept evidence for the therapeutic potential of intranasal oxytocin in mental disorders with dysfunctional interoception.

Should Adolescents Listen to Their Hearts? A Closer Look at the Associations Between Interoception, Emotional Awareness and Emotion Regulation in Adolescents

The aim of the current study was to replicate findings from prior work among adults showing that individuals with better interoceptive skills have more emotional awareness, and show better emotion regulation abilities, in a sample of adolescents and by relying on instructions that reduce the contamination of known confound variables. A total of 102 Belgian adolescents (Mage = 14.10 years, SDage = .63; 50 males) completed self-report questionnaires of emotional processes (FEEL-KJ and DERS) and the modified heartbeat counting task. From this task, interoceptive accuracy, interoceptive sensibility (confidence ratings), and interoceptive awareness scores (within-person correlations) were derived per participant. Results revealed no associations between the three dimensions of interoception and adolescents' levels of emotional awareness, adaptive, and maladaptive emotion regulation. The lack of associations which contrast some prior work with adults may be due to developmental differences. However, these might also support the low validity of the heartbeat counting task, or could be attributed to the measurement of the emotion measures (i.e., self-report). Future studies should, nevertheless, also test whether these non-significant results can be explained by the developmental differences in adolescents. Longitudinal research is needed to capture interoceptive changes during adolescence, as well as to replicate the current findings using rigorous multimethod approaches that increase the validity of interoception measurement.

Heart rate and insula activity increase in response to music in individuals with high interoceptive sensitivity

Interoception plays an important role in emotion processing. However, the neurobiological substrates of the relationship between visceral responses and emotional experiences remain unclear. In the present study, we measured interoceptive sensitivity using the heartbeat discrimination task and investigated the effects of individual differences in interoceptive sensitivity on changes in pulse rate and insula activity in response to subjective emotional intensity. We found a positive correlation between heart rate and valence level when listening to music only in the high interoceptive sensitivity group. The valence level was also positively correlated with music-elicited anterior insula activity. Furthermore, a region of interest analysis of insula subregions revealed significant activity in the left dorsal dysgranular insula for individuals with high interoceptive sensitivity relative to individuals with low interoceptive sensitivity while listening to the high-valence music pieces. Our results suggest that individuals with high interoceptive sensitivity use their physiological responses to assess their emotional level when listening to music. In addition, insula activity may reflect the use of interoceptive signals to estimate emotions.

Blind individuals' enhanced ability to sense their own heartbeat is related to the thickness of their occipital cortex

Blindness is associated with heightened sensory abilities, such as improved hearing and tactile acuity. Moreover, recent evidence suggests that blind individuals are better than sighted individuals at perceiving their own heartbeat, suggesting enhanced interoceptive accuracy. Structural changes in the occipital cortex have been hypothesized as the basis of these behavioral enhancements. Indeed, several studies have shown that congenitally blind individuals have increased cortical thickness within occipital areas compared to sighted individuals, but how these structural differences relate to behavioral enhancements is unclear. This study investigated the relationship between cardiac interoceptive accuracy and cortical thickness in 23 congenitally blind individuals and 23 matched sighted controls. Our results show a significant positive correlation between performance in a heartbeat counting task and cortical thickness only in the blind group, indicating a connection between structural changes in occipital areas and blind individuals' enhanced ability to perceive heartbeats.

Disrupted interoceptive awareness by auditory distractor: Difficulty inferring the internal bodily states?

Recent studies have associated interoceptive awareness, the perception of internal bodily sensations, with a predictive mechanism of perception across all sensory modalities. According to the framework, volitional attention plays a pivotal role in interoceptive awareness by prioritizing interoceptive sensations over exteroceptive ones. Consequently, it is hypothesized that the presence of irrelevant stimuli would disrupt the attentional modulation and interoceptive awareness, which remains untested. In this study, we investigated if interoceptive awareness is diminished by unrelated auditory distractors to validate the proposed perceptual framework. A total of 30 healthy human volunteers performed the heartbeat counting task both with and without auditory distractors. Additionally, we measured participant's psychophysiological traits related to interoception, including the high-frequency component of heart rate variability (HF-HRV) and trait interoceptive sensibility. The results showed that interoceptive accuracy, confidence, and heartbeat intensity decreased in the presence of distractor sound. Moreover, individuals with higher HF-HRV and a greater tendency to worry about bodily states experienced a more pronounced distractor effect on interoceptive awareness. These results provide support for the perceptual mechanism of interoceptive awareness in terms of the predictive process, highlighting the impact of relative precision across interoceptive and exteroceptive signals on perceptual experiences.

Heart activity perception: narrative review on the measures of the cardiac perceptual ability

Measures of cardiac perceptual ability (also called cardiac accuracy) are methods of cardiac interoception, the perception of bodily sensation related to heart activity. This narrative review aims to provide an overview of these methods. We differentiate between three main measurement types: (1) change detection, i.e., when the task is to notice the change in the heart rate; also called: heart rate perception tasks, (2) discrimination tasks, i.e., when the task is to compare the internal sensations with external signal(s); also called: heartbeat detection tasks and (3) tracking tasks, i.e., when the task is to follow and report heartbeats via tapping or counting. We describe some of the new methods under "mixed methods," as they share features with more than one of the large measurement types described above. Specific measures differ in various aspects, such as their focus (heart rhythm vs. single beats), their sensitivity to non-conscious sensations and the calculated indices (e.g., whether significance level by hypothesis test is provided). When a measure of cardiac perceptual ability is chosen, it is advisable to take its characteristics into consideration in light of the planned research.

The effect of 10-week long yoga training on interoceptive abilities: cross-sectional and longitudinal investigation of cardiac and gastric accuracy

Based on their characteristics, it is likely that mind-body techniques develop interoception, the perception of bodily state. Nevertheless, findings on mindfulness, meditation, yoga, and body scan techniques are inconclusive. Additionally, the methodological scope is not exhaustive, neither in terms of the intervention nor the applied measure of interoception. This study investigated for the first time the effect of regular yoga training on cardiac and gastric perceptual ability (measured with the mental heartbeat tracking task and the water load task, respectively). With the involvement of 90 female university students (yoga group n = 57, control group n = 33) we did not find any connection between baseline heartbeat perception score and gastric fullness. Moreover, the applied 10-week-long regular yoga training did not develop any of the measured interoceptive abilities. We conclude that yoga might develop other abilities than these specific sensations. Very probably, the measured cardiac and gastric perceptual abilities do not represent bodily sensations in general. It would be worth to investigate, however, the effect of longer yoga training on interoception.

Recognition of others' interoceptive states in those with and without eating disorders

BACKGROUND

The ability to recognize one's own emotions is associated with one's ability to recognize others' emotions. Beyond the domain of emotion, however, the relationship between recognition of one's own internal states (interoception) and others' interoceptive states has not been investigated, either in the typical population or clinical groups with interoceptive difficulties (e.g. eating disorders; EDs).

METHOD

This study investigated recognition of one's own and others' internal states in adults with and without eating disorders, using a high frequency visual noise paradigm. Participants completed self-report measures of interoception, alexithymia (difficulties recognising one's own emotional internal states) and ED symptomatology, and the Heartbeat Counting Task measure of cardiac interoceptive accuracy.

RESULTS

Alexithymia was significantly negatively correlated with recognition of others' interoceptive states. EDs were not associated with difficulties recognising others' interoceptive states.

CONCLUSIONS

The ability to recognise one's own emotional internal states is associated with the recognition of others' interoceptive states, which may contribute to social skills and the ability to care for others.

Heightened interoception in adults with fibromyalgia

Previous research suggests that the processing of internal body sensations (interoception) affects how we experience pain. Some evidence suggests that people with fibromyalgia syndrome (FMS) - a condition characterised by chronic pain and fatigue - may have altered interoceptive processing. However, extant findings are inconclusive, and some tasks previously used to measure interoception are of questionable validity. Here, we used an alternative measure - the Phase Adjustment Task (PAT) - to examine cardiac interoceptive accuracy in adults with FMS. We examined: (i) the tolerability of the PAT in an FMS sample (N = 154); (ii) if there are differences in facets of interoception (PAT performance, PAT-related confidence, and scores on the Private Body Consciousness Scale) between an FMS sample and an age- and gender-matched pain-free sample (N = 94); and (iii) if subgroups of participants with FMS are identifiable according to interoceptive accuracy levels. We found the PAT was tolerable in the FMS sample, with additional task breaks and a recommended hand posture. The FMS sample were more likely to be classified as 'interoceptive' on the PAT, and had significantly higher self-reported interoception compared to the pain-free sample. Within the FMS sample, we identified a subgroup who demonstrated very strong evidence of being interoceptive, and concurrently had lower fibromyalgia symptom impact (although the effect size was small). Conversely, self-reported interoception was positively correlated with FMS symptom severity and impact. Overall, interoception may be an important factor to consider in understanding and managing FMS symptoms. We recommend future longitudinal work to better understand associations between fluctuating FMS symptoms and interoception.

Investigating the relationship between self-reported interoceptive experience and risk propensity

Risky behaviour may be associated with visceral experiences, such as increased heart rate. Previous studies examining the relationship between perception of such signals (interoception) and risk-taking typically used behavioural tasks with potential for monetary reward. This approach may be less informative for understanding general risk propensity. In addition, such research does not usually consider the varied ways individuals engage with interoceptive signals. However, examining these different forms of engagement may help us understand how subjective experience of interoception influences risk-taking. As such, we performed two surveys (n = 471, primarily young adults) to examine the relationship between self-reported engagement with interoceptive signals (measured using the Multidimensional Assessment of Interoceptive Awareness) and a generalised measure of risk propensity (the General Risk Propensity Scale). Results indicated that different ways of interpreting or engaging with interoceptive signals were differentially associated with risk propensity. In particular, they provide preliminary evidence that those with the ability to ignore or not worry about visceral signals when they are uncomfortable display greater risk propensity (and these effects may possibly be gender-specific).

Thermosensation and emotion: Thermosensory accuracy in a dynamic thermal matching task is linked to depression and anxiety symptomatology

Interoception is related to the generation of bodily feelings and the awareness of ourselves as 'sentient beings', informing the organism about its bodily needs to guarantee survival. Previous studies have reported links among interoception, emotion processing, and mental health. For example, the alignment of interoceptive dimensions (i.e., accuracy, sensibility, awareness) can predict emotional symptoms, such as anxiety. Here, we aimed to investigate the relationship between the perception of a certain type of skin-mediated interoceptive signal, i.e., thermosensation, and self-reported depression, anxiety, and stress. One hundred seventy participants completed the Depression Anxiety Stress Scale (DASS-21) and a dynamic thermal matching task, a static temperature detection task, and a heartbeat counting task. Our results revealed that self-reported anxiety and depression were related to the perception of temperature on hairy and non-hairy skin, respectively: higher anxiety was related to better performance on the thermal matching task on the forearm, while higher depression was related to poorer performance on dynamic and static temperature tasks on the palm. Discrepancies between thermosensory accuracy and sensibility measures ('trait prediction error') were related to heightened anxiety, in line with previous studies. No significant correlations were found between DASS-21 scores and heartbeat counting accuracy. In conclusion, this study suggests that individual differences in thermosensory perception in different areas of the body are associated with self-reported anxiety and depression.

The misjudgment of interoceptive awareness: Systematic overrating of interoceptive awareness among individuals with lower interoceptive metacognitive skills

Knowing when perceiving inner bodily signals better and when perceiving them worse is a health relevant but understudied dimension of interoception. Therefore, the present study assessed interoceptive metacognition (IMC) as the skill to adequately monitor interoceptive accuracy in the cardiac domain. We used the Graz Ambulatory Interoception task (GRAIT), which applied two intervals of the heartbeat tracking task 12 times a day for 3 days in total to n = 66 participants. We assessed IMC as the relative correspondence between interoceptive accuracy and the subjective confidence ratings. We found that 6 % of the total IMC variance was due to person, which was assessed reliable (RKRn=0.81). Furthermore, the between-person variation of IMC was negatively associated with the MAIA (especially attention regulation and self-regulation). People who believe that they are aware of their interoceptive experiences (MAIA) showed lower IMC. This study advocates the assessment of interoception in everyday life.

"Listen to your heart": A novel interoceptive strategy for real-time fMRI neurofeedback training of anterior insula activity

Real-time fMRI (rt-fMRI) neurofeedback (NF) training is a novel non-invasive technique for volitional brain modulation. Given the important role of the anterior insula (AI) in human cognitive and affective processes, it has become one of the most investigated regions in rt-fMRI studies. Most rt-fMRI insula studies employed emotional recall/imagery as the regulation strategy, which may be less effective for psychiatric disorders characterized by altered emotional processing. The present study thus aimed to examine the feasibility of a novel interoceptive strategy based on heartbeat detection in rt-fMRI guided AI regulation and its associated behavioral changes using a randomized double-blind, sham feedback-controlled between-subject design. 66 participants were recruited and randomly assigned to receive either NF from the left AI (LAI) or sham feedback from a control region while using the interoceptive strategy. N = 57 participants were included in the final data analyses. Empathic and interoceptive pre-post training changes were collected as behavioral measures of NF training effects. Results showed that participants in the NF group exhibited stronger LAI activity than the control group with LAI activity being positively correlated with interoceptive accuracy following NF training, although there were no significant increases of LAI activity over training sessions. Importantly, ability of LAI regulation could be maintained in a transfer session without feedback. Successful LAI regulation was associated with strengthened functional connectivity of the LAI with cognitive control, memory and learning, and salience/interoceptive networks. The present study demonstrated for the first time the efficacy of a novel regulation strategy based on interoceptive processing in up-regulating LAI activity. Our findings also provide proof of concept for the translational potential of this strategy in rt-fMRI AI regulation of psychiatric disorders characterized by altered emotional processing.

Interoception and the musical brain: Evidence from cross-sectional and longitudinal behavioral and resting-state fMRI study

Musical training has been linked to enhanced interoceptive abilities and increased resting-state (RS) functional connectivity (FC) within the interoceptive brain network. We aimed to replicate and extend these findings with a unique cross-sectional and longitudinal study design. Professional musicians and matched individuals with no prior musical experience (training group) were recruited. Participants underwent RS fMRI scans and completed heartbeat counting and discrimination tasks outside of the scanner (time point 1). The training group additionally had RS scans and interoception tests repeated after a 6-month-long keyboard course training (time point 2). We found no evidence for increased interoceptive abilities in professional musicians relative to non-musicians, nor did we observe any improvements in interoception over the course of musical training. RS FC analysis revealed increased FC within the sensorimotor network in professional musicians compared to the training group at the first time point with no change in FC over time in the Training group. These findings challenge the view that musical training may improve interoceptive abilities. Yet, the results suggest that musical training is related to increased communication within the sensorimotor RS network, which consists of some hubs important for interoceptive processing (namely pre- and postcentral gyri and supplementary motor area).

Is that My Heartbeat? Measuring and Understanding Modality-Dependent Cardiac Interoception in Virtual Reality

Measuring interoception ('perceiving internal bodily states') has diagnostic and wellbeing implications. Since heartbeats are distinct and frequent, various methods aim at measuring cardiac interoceptive accuracy (CIAcc). However, the role of exteroceptive modalities for representing heart rate (HR) across screen-based and Virtual Reality (VR) environments remains unclear. Using a PolarH10 HR monitor, we develop a modality-dependent cardiac recognition task that modifies displayed HR. In a mixed-factorial design (N=50), we investigate how task environment (Screen, VR), modality (Audio, Visual, Audio-Visual), and real-time HR modifications (±15%, ±30%, None) influence CIAcc, interoceptive awareness, mind-body measures, VR presence, and post-experience responses. Findings showed that participants confused their HR with underestimates up to 30%; environment did not affect CIAcc but influenced mind-related measures; modality did not influence CIAcc, however including audio increased interoceptive awareness; and VR presence inversely correlated with CIAcc. We contribute a lightweight and extensible cardiac interoception measurement method, and implications for biofeedback displays.

Increasing familiarity with the heartbeat counting task does not affect performance

BACKGROUND

Interoception is typically defined as the processing and perception of internal signals. A common evaluation of interoceptive abilities is the heartbeat counting task, during which participants count their heartbeats over a period of time. It has been argued recently, however, that performance in this task may reflect processes other than cardiac sensation.

OBJECTIVE

This study aimed to: 1) observe heartbeat counting task performance changes across multiple repetitions of the task; and 2) compare performance in the heartbeat counting task with that for a visual counting task to investigate generalised propensities for how uncertain stimuli are reported.

METHODS

Seventy-nine healthy participants performed seven blocks each of the heartbeat and visual counting tasks. Scores for each of the tasks were compared across blocks to identify any change in performance. Performance in the two tasks was then correlated. The study was preregistered at https://doi.org/10.17605/OSF.IO/GWAB7.

RESULTS

Heartbeat counting task performance did not change over blocks. In contrast, scores for the visual counting task reduced over time. A positive correlation was seen between performance in the two tasks (ρ(79) = .27).

CONCLUSION

Heartbeat counting task performance is stable across repetitions of the task, not changing with increasing familiarity. This suggests that non-interoceptive factors, such as beliefs, may be involved. The correlation between the heartbeat and visual counting tasks may point to a general propensity in counting uncertain stimuli across sensory domains. Together, these results raise questions about the interpretation of the heartbeat counting task as a measure of interoception.

Mental health meets computational neuroscience: A predictive Bayesian account of the relationship between interoception and multisensory bodily illusions in anorexia nervosa

Mental health disorders pose a significant challenge to society. The Bayesian perspective on the mind offers unique insights and tools that may help address a variety of mental health conditions. Psychopathological dysfunctions are often connected to altered predictive and active inference processes, in which cognitive and physiological pathogenic beliefs shape the clinical condition and its symptoms. However, there is a lack of general empirical models that integrate cognitive beliefs, physiological experience, and symptoms in healthy and clinical populations. In this study, we examined the relationship between altered predictive mechanisms, interoception, and pathological bodily distortions in healty individuals and in individuals suffering from anorexia nervosa (AN). AN patients (N=15) completed a Virtual Reality Full-Body Illusion along with interoceptive tasks twice: at hospital admission during an acute symptomatological phase (Time 1) and after a 12-week outpatient clinical weight-restoring rehabilitative program (Time 2). Results were compared to a healthy control group. Our findings indicated that higher levels of interoceptive metacognitive awareness were associated with a greater embodiment. However, unlike in healthy participants, AN patients' interoceptive metacognition was linked to embodiment even in multisensory mismatching (asynchronous) conditions. In addition, unlike in healthy participants, higher interoceptive metacognition in AN patients was related to prior abnormal bodily distortions during the acute symptomatology phase. Prediction errors in bodily estimates predicted posterior bodily estimate distortions after the illusion, but while this relationship was only significant in the synchronous condition in healthy participants, there was no significant difference between synchronous and asynchronous conditions in AN patients. Despite the success of the rehabilitation program in restoring some dysfunctional patterns in the AN group, prediction errors and posterior estimate distortions were present at hospital discharge. Our findings suggest that individuals with AN prioritize interoceptive metacognitive processes (i.e., confidence in their own perceived sensations rather than their actual perceptions), disregarding bottom-up bodily inputs in favour of their prior altered top-down beliefs. Moreover, even if the rehabilitative program partially mitigated these alterations, the pathological condition impaired the patients' ability to coherently update their prior erroneous expectations with real-time multisensory bottom-up bodily information, possibly locking the patients in the experience of a distorted prior top-down belief. These results suggest new therapeutic perspectives and introduce the framework of regenerative virtual therapy (RVT), which aims at utilizing technology-based somatic modification techniques to restructure the maladaptive priors underlying a pathological condition.

Dynamic heartbeat tracking beyond the laboratory: Introducing the novel Graz Ambulatory Interoception Task (GRAIT)

We present a novel ambulatory method, the Graz Ambulatory Interoception Task (GRAIT), to assess the accuracy of interoceptive beliefs (AccIB). This method captures both between- and within-person variations of AccIB by having participants counting perceived heartbeats in daily life. Reliability analyses showed high between-person (RkR = 0.99) and moderate within-person reliability (RCn = 0.62). Validity was supported by associations with an established laboratory task (r = 0.87). Within-person associations revealed that interoceptive sensibility, heart rate variability, and states of low arousal coupled with positive affect were linked to AccIB. Study 2 replicated these findings and showed a relationship between AccIB and self-control in everyday life, highlighting the importance of cardiac interoception and its relevance for health.

Mind your heart to bear the weight: Cardiac interoception predicts action-related visual perception when wearing a heavy backpack

Visual perception can be modulated by the physiological potential for action. For instance, it was famously shown that a geographical slant appears steeper when wearing a heavy backpack than not wearing any. However, those results are not always replicated. In the present exploratory study, we test the hypothesis that the backpack weight's effect on perception relies on the ability of the cognitive system to integrate the physiological constraint's change rather than the change itself. Young adults (n = 54) wore an electrocardiogram monitor and completed a computerised task in which photographs of real geographical slants were displayed on a screen while wearing a heavy versus light backpack. The activity of the vagus nerve, as an index of physiological adaptability, was recorded as a proxy of the physiological state during the task. The participants also completed an interoception task assessing one's ability to detect his or her own heartbeat as the index of integration ability of the cognitive system. While Bayesian analyses revealed no difference in angle estimation between carrying a heavy versus light backpack, the results indicated that interoception predicted less accurate angle estimation only when wearing a heavy backpack. In contrast, there was anecdotal evidence that vagal activity changes predicted visual perception. Interoception might thus play a crucial role in the interplay between the physiological potential for action and action-related visual perception.

The new measures of interoceptive accuracy: A systematic review and assessment

Conscious interoception, the perception of internal bodily states, is thought to contribute to fundamental human abilities (e.g., decision-making and emotional regulation). One of its most studied dimensions is interoceptive accuracy: the objective capacity to detect internal bodily signals. In the past few years, several labs across the world have started developing new tasks aimed at overcoming limitations inherent in classical measures of interoceptive accuracy. In this systematic review, we identified these tasks (since 2015) for the cardiac, respiratory, and gastrointestinal domains. For each identified task, we discuss their strengths and weaknesses, and make constructive suggestions for further improvement. In the general discussion, we discuss the (potentially elusive) possibility of reaching high validity in the measurement of interoceptive accuracy. We also point out that interoceptive accuracy may not be the most critical dimension for informing current theories, and we encourage researchers to investigate other dimensions of conscious interoception.

A multi-site German validation of the Interoceptive Accuracy Scale and its relation to psychopathological symptom burden

Altered interoception is thought to be implicated in the development of psychopathology. Recent proposals highlight the need to differentiate between dimensions of interoception to better understand its relation to mental health. Here, we validated a German version of the Interoceptive Accuracy Scale (IAS) and investigated the relationship between IAS scores and clinical outcomes, across seven samples from four research centers (N = 3462). The German IAS version was best explained by a one-factor structure that showed acceptable psychometric properties. We replicated previous findings showing a negative association between IAS scores and measures of alexithymia. IAS scores were negatively related to measures of clinical symptomatology (e.g., anxiety, depressive, and somatoform symptoms) and neurotic traits. These findings suggest that the German IAS is a reliable and valid instrument for subjective interoceptive accuracy. Results emphasize the importance of distinguishing between dimensions of interoception to understand its potential modulatory and protective role in psychopathology.

Interoception in functional motor symptoms and functional seizures: Preliminary evidence of intact accuracy alongside reduced insight and altered sensibility

Altered interoception may be a pathophysiological mechanism in functional neurological disorder (FND). However, findings have been inconsistent across interoceptive dimensions in FND including functional motor symptoms (FMS) and seizures (FS). Here, individuals with FMS/FS (n = 17) and healthy controls (HC, n = 17) completed measures of interoceptive accuracy and insight (adapted heartbeat tracking task [HTT] with confidence ratings), a time estimation control task (TET) and the Multidimensional Assessment of Interoceptive Awareness-2 (MAIA-2) to assess interoceptive sensibility. The groups did not differ in interoceptive accuracy (p = 1.00, g = 0.00) or confidence (p = .99, g = 0.004), although the FMS/FS group displayed lower scores on the "Not-Distracting" (p < .001, g = 1.42) and "Trusting" (p = .005, g = 1.17) MAIA-2 subscales, relative to HCs. The groups did not differ in TET performance (p = .82, g = 0.08). There was a positive relationship between HTT accuracy and confidence (insight) in HCs (r = .61, p = .016) but not in FMS/FS (r = 0.11, p = .69). HTT confidence was positively correlated with MAIA-2 "Self-Regulation" (r = 0.77, p = .002) and negatively correlated with FND symptom severity (r = -0.84, p < .001) and impact (r = -0.86, p < .001) in FMS/FS. Impaired interoceptive accuracy may not be a core feature in FMS/FS, but reduced insight and altered sensibility may be relevant. Reduced certainty in self-evaluations of bodily experiences may contribute to the pathogenesis of FND symptoms.

The impact of interoceptive accuracy and stimulation type on the out-of-body experience

People tend to perceive a virtual body standing in front of them as their own if it is either stroked or moving synchronously with their own real body-the out-of-body experience (OBE). We combined synchrony manipulation with two other factors of theoretical interest: the kind of stimulation, visuotactile stimuli or visuomotor correlations, being synchronised and the interoceptive accuracy (IA) of participants, assessed by means of the heartbeat counting task. Results showed that explicit measures of embodiment were systematically affected by synchrony, and this synchrony effect was more pronounced for visuomotor than for visuotactile conditions. The walking drift was affected by IA: In visuotactile conditions, the synchrony effect was pronounced in individuals with low IA, presumably reflecting a stronger impact of the visual information. In visuomotor conditions, however, the synchrony effect was stronger in individuals with high IA, presumably reflecting a stronger impact of re-afferent information generated by the participants' own movements.

Reduced Interoception Abilities in Patients with Restless Legs Syndrome

Background

Restless legs syndrome (RLS) is a complex sensorimotor disorder occurring with a typical circadian fashion. Association with additional features, like alexithymia and nocturnal compulsive behaviors further complicates the framework.

Objectives

To assess interoception in RLS.

Methods

A total of 25 RLS patients and 28 controls underwent the heartbeat tracking task (interoceptive accuracy [IAC]). RLS symptoms' frequency, disturbance and duration, nocturnal behaviors, interoceptive awareness (IAW), alexithymia, depressive and anxiety symptoms were also collected.

Results

RLS patients showed significant lower IAC (P = 0.0003) and IAW (P = 0.012), and reported more nocturnal eating behaviors (P < 0.001). IAC positively correlated with IAW (R = 0.32), and negatively correlated with age (R = -0.58). Nocturnal eating behavior negatively correlated with IAC (R = -0.44) and IAW (R = -0.50).

Conclusions

RLS patients presented reduced interoceptive abilities correlating with higher nocturnal eating behaviors. Future studies are needed to explore the role of interoception in RLS pathophysiology, also in relation to other sensorimotor aspects.

Interoceptive abilities facilitate taking another's spatial perspective

Information can be perceived from a multiplicity of spatial perspectives, which is central to effectively understanding and interacting with our environment and other people. Interoception, the sense of the physiological state of our body, is also a fundamental component contributing to our perception. However, whether the perception of our inner body signals influences our ability to adopt and flexibly change between different spatial perspectives remains poorly understood. To investigate this, 90 participants completed tasks assessing multiple dimensions of interoception (interoceptive sensibility, cardiac interoceptive accuracy and awareness) and the Graphesthesia task to assess tactile spatial perspective-taking and its flexibility. The results revealed that higher cardiac interoceptive awareness is associated with greater consistency in adopting a perspective decentred from the self. Second, higher cardiac interoceptive accuracy was associated with slower and less accurate performance in switching from a decentred to an egocentred perspective. These results show that interoceptive abilities facilitate decentred spatial perspective-taking, likely reflecting stronger perceived boundaries between internal states and the external world.

Interoception Within the Context of Impulsivity and Addiction

Purpose of Review

The goal of this review is to examine the relationship between impulsivity and interoception in addiction, to summarize the current understanding of the topic, identify any gaps in knowledge, and provide directions for future research.

Research Findings

Interoception may be a contributing factor to impulsive behaviour and, thus, addiction. Substance abuse can negatively impact the brain's ability to process interoceptive information and impact the reward system, leading to decreased sensitivity to natural rewards and increased sensitivity to drugs. There is potential for new therapies, such as mindfulness, interoceptive training, brain stimulation, or vagal nerve stimulation to target both impulsivity and interoception in the treatment of addiction.

Summary

Despite a growing interest in interoception in addiction research, further research is needed to better understand the role of interoception in addiction and to develop new methods for studying how individuals with addiction process and perceive internal bodily sensations.