People with higher interoceptive sensitivity are more altruistic, but improving interoception does not increase altruism

The thermoception task: a thermal imaging-based procedure for measuring awareness of changes in peripheral body temperature

Although thermal body signals provide crucial information about the state of an organism and changes in body temperature may be a sign of affective states (e.g., stress, pain, sexual arousal), research on thermal awareness is limited. Here we developed a task measuring awareness of changes in peripheral body temperature (thermal interoception) and compared it to the classical heartbeat counting task (cardiac interoception). With an infrared light bulb we delivered stimuli of different temperature intensities to the right hand of 31 healthy participants. Thermal interoceptive accuracy, i.e., the difference between participants' real and perceived change in hand temperature, showed good interindividual variability. We found that thermal interoception did not correlate with (and was generally higher than) cardiac interoception, suggesting that different interceptive channels provide separate contributions to awareness of bodily states. Moreover, the results hint at the great salience of thermal signals and the need for thermoregulation in day-to-day life. Finally, thermal interoceptive accuracy was associated with self-reported awareness of body temperature changes and with the ability to regulate distress by focusing on body sensations. Our task has the potential to significantly increase current knowledge about the role of interoception in cognition and behavior, particularly in social and emotional contexts.NEW & NOTEWORTHY We developed a novel task measuring awareness of changes in peripheral body temperature (i.e., thermal interoception). To avoid tactile confounds present in existing thermoceptive tasks, we used an infrared light bulb to deliver stimuli of different temperature intensities to the hand of participants and asked them to judge the perceived change in their hand temperature. Performance in the task showed good interindividual variability, did not correlate with cardiac interoceptive tasks, and was associated with self-reported thermosensitivity.

Dysfunctional self-reported interoception predicts residual symptom burden of fatigue in major depressive disorder: an observational study

BACKGROUND

Fatigue is a core symptom of major depressive disorder (MDD) and is frequently refractory to antidepressant treatment, leading to unfavorable clinical/psychosocial outcomes. Dysfunctional self-reported interoception (i.e., maladaptive focus on the body's physiological condition) is prevalent in MDD and could contribute to residual symptom burden of fatigue. Therefore, we explored (a.) cross-sectional correlations between both dimensions and investigated (b.) prospective associations between interoceptive impairments at admission and symptom severity of fatigue at the end of hospitalization.

METHODS

This observational, exploratory study included 87 patients suffering from MDD who completed self-rating scales, the Multidimensional Assessment of Interoceptive Awareness, Version 2 (MAIA-2), and the Multidimensional Fatigue Inventory (MFI-20), at the beginning and end of hospitalization. Bivariate correlations (r) and hierarchical regression analyses were performed.

RESULTS

The cross-sectional analysis showed moderate to large negative correlations between the MAIA-2 and MFI-20 dimensions except for the Not-Distracting scale. Symptoms of general, physical, and mental fatigue at the end of hospitalization were predicted by reduced body Trusting (β = -.31, p = .01; β = -.28, p = .02; β = -.31, p = .00, respectively). Increased Body Listening (β = .37, p = .00), Not-Worrying (β = .26, p = .02), and diminished Attention Regulation (β = -.32, p = .01) predicted higher mental fatigue.

CONCLUSIONS

Diminished body confidence at baseline identified patients at risk for post-treatment fatigue and could therefore serve as a target for improving antidepressant therapy. Body-centered, integrative approaches could address treatment-resistant fatigue in MDD. However, clinicians may also consider the potential adverse effect of increased Body Listening and Not-Worrying on mental fatigue in psychotherapeutic and counselling approaches. Due to the exploratory nature of this study, the results are preliminary and need to be replicated in pre-registered trials with larger sample sizes.

Neural representations of vicarious rewards are linked to interoception and prosocial behaviour

Every day we constantly observe other people receiving rewards. Theoretical accounts posit that vicarious reward processing might be linked to people's sensitivity to internal body states (interoception) and facilitates a tendency to act prosocially. However, the neural processes underlying the links between vicarious reward processing, interoception, and prosocial behaviour are poorly understood. Previous research has linked vicarious reward processing to the anterior cingulate gyrus (ACCg) and the anterior insula (AI). Can we predict someone's propensity to be prosocial or to be aware of interoceptive signals from variability in how the ACCg and AI process rewards? Here, participants monitored rewards being delivered to themselves or a stranger during functional magnetic resonance imaging. Later, they performed a task measuring their willingness to exert effort to obtain rewards for others, and a task measuring their propensity to be aware and use interoceptive respiratory signals. Using multivariate similarity analysis, we show that people's willingness to be prosocial is predicted by greater similarity between self and other representations in the ACCg. Moreover, greater dissimilarity in self-other representations in the AI is linked to interoceptive propensity. These findings highlight that vicarious reward is linked to bodily signals in AI, and foster prosocial tendencies through the ACCg.

A longitudinal study of interoception changes in the times of COVID-19: Effects on psychophysiological health and well-being

Background

Interoception - the processing of the internal state of the body - has been consistently tied to well-being and mental health, which in turn have been severely challenged by the COVID-19 pandemic. Moreover, the fact that symptoms of COVID-19 (high temperature, shortness of breath, fatigue, and even gastro-intestinal problems) directly alter interoceptive signals has fueled people's tendency to constantly check their internal bodily state.

Objectives

In this longitudinal study we tested for changes in interoception and psychophysiological health and well-being during different stages of the pandemic in 2020 and assessed their potential association. To highlight this association, we combined both subjective (i.e., self-reported questionnaires) and objective (i.e., measures of heart rate variability, HRV and of interoceptive accuracy) measures.

Methods

245 Italian participants who had completed the Multidimensional Assessment of Interoceptive Awareness (MAIA-2) prior to the onset of the pandemic, repeated the questionnaire during the first national lockdown in Italy, and four months after restrictions. Participants also completed survey measures of depression (PHQ-9), anxiety (STAI), and sleep disturbance (PSQI). A sub-sample of 28 participants, who had completed the heartbeat counting task (HCT) and a measure of heart rate variability (HRV), was tested again remotely, in the same time windows, using phone applications and photoplethysmography.

Results

While performance in the HCT remained unvaried, MAIA-2 scores consistently increased from before the pandemic to the national lockdown, and remained largely unvaried after four months. The national lockdown was associated with the lowest psychophysiological health and well-being, as evidenced by a decrease in HRV compared to before the pandemic and by higher scores in self-reported depression, anxiety, and sleep disturbance compared to four months after the lockdown. Interestingly, psychophysiological health and well-being were predicted by specific regulatory components of interoception (e.g., the ability to regulate distress by focusing on body sensations and experiencing one's body as safe and trustworthy).

Conclusions

Our results suggest an increased attention towards visceral signals during the COVID-19 pandemic, and highlight the positive role of specific components of interoception in contributing to well-being, suggesting that novel interventions aimed at increasing interoception may be developed to protect against stressful life events such as COVID-19.

Reduced ownership over a virtual body modulates dishonesty

Although studies suggest that even higher-order functions can be embodied, whether body awareness may bias moral decisions toward (dis)honesty remains underinvestigated. Here, we tested if the Sense of body Ownership (SoO) and the magnitude of monetary rewards influence the tendency to act immorally. Through a virtual body, participants played a card game in which they could lie to others to steal high or low amounts of money. To manipulate SoO, the virtual body was seen and controlled from a first-person perspective, with hands attached or detached, or from a third-person perspective. In third-person perspective, SoO was significantly reduced and more egoistic lies were produced in high reward conditions. Thus, SoO reduction and high monetary reward facilitate dishonest behavior, likely by separating the self from the dishonest actions performed through the disowned body. Because most future interactions will likely occur in a digital metaverse, our results may have crucial societal impact.

Judgment and Embodied Cognition of Lawyers. Moral Decision-Making and Interoceptive Physiology in the Legal Field

Past research showed that the ability to focus on one’s internal states (e.g., interoceptive ability) positively correlates with the self-regulation of behavior in situations that are accompanied by somatic and/or physiological changes, such as emotions, physical workload, and decision-making. The analysis of moral oriented decision-making can be the first step for better understanding the legal reasoning carried on by the main players in the field, as lawyers are. For this reason, this study investigated the influence of the decision context and interoceptive manipulation on the moral decision-making process in the legal field gathering the responses of two groups of lawyers. A total of 20 lawyers were randomly divided into an experimental group (EXP), which was explicitly required to focus the attention on its interoceptive correlates, and a control group (CON), which only received the general instruction to perform the task. Both groups underwent a modified version of the Ultimatum Game (UG), where are presented three different moral conditions (professional, company, and social) and three different offers (fair, unfair, and equal). Results highlighted a significant increase of Acceptance Rate (AR) in those offers that should be considered more equal than fair or unfair ones, associated with a general increase of Reaction Times (RTs) in the equal offers. Furthermore, the interoceptive manipulation oriented the Lawyers toward a more self-centered decision. This study shows how individual, situational, contextual, and interoceptive factors may influence the moral decision-making of lawyers. Future research in the so-called Neurolaw field is needed to replicate and expand current findings.

Interoceptive Accuracy Did Not Affect Moral Decision-Making, but Affect Regret Rating for One’s Moral Choices

Previous studies have revealed the effect of interoceptive accuracy (IAcc), a behavioral measure of the ability to feel physiological states and regulation for that, which origin emotion on decision-making such as gambling. Given that decision-making in moral dilemma situations is affected by emotion, it seems that IAcc also affects moral decision-making. The present study preliminarily investigates whether IAcc affects decision-making and emotional ratings such as regret for one’s own choices in moral dilemma situations. IAcc did not affect moral choice (deontological or utilitarian option), but affected regret ratings for one’s moral choice in portions of dilemma scenarios. Moreover, people with higher IAcc make deontological choices more rapidly than those with lower IAcc in self-related dilemma scenarios. These results suggest that people with higher IAcc feel stronger emotional conflicts about utilitarian choices but weaker conflicts about deontological choices than people with lower IAcc depending on the moral dilemma scenario.

Atypical interoception as a common risk factor for psychopathology: A review

The inadequacy of a categorial approach to mental health diagnosis is now well-recognised, with many authors, diagnostic manuals and funding bodies advocating a dimensional, trans-diagnostic approach to mental health research. Variance in interoception, the ability to perceive one's internal bodily state, is reported across diagnostic boundaries, and is associated with atypical functioning across symptom categories. Drawing on behavioural and neuroscientific evidence, we outline current research on the contribution of interoception to numerous cognitive and affective abilities (in both typical and clinical populations), and describe the interoceptive atypicalities seen in a range of psychiatric conditions. We discuss the role that interoception may play in the development and maintenance of psychopathology, as well as the ways in which interoception may differ across clinical presentations. A number of important areas for further research on the role of interoception in psychopathology are highlighted.

Can changes in multidimensional self-reported interoception be considered as outcome predictors in severely depressed patients? A moderation and mediation analysis

OBJECTIVE

Somatic complaints (e.g. pain) and abnormal self-reported interoception (e.g. maladaptive bodily self-focus) are common features of major depressive disorder (MDD) with sex-specific manifestations. Whereas somatic symptoms are associated with adverse clinical outcomes (e.g. residual symptoms), studies are scarce investigating the role of interoception as an outcome predictor for specific hospital treatment of MDD. Therefore, multivariate associations between changes in multidimensional self-reported interoception, somatic symptoms, and clinical improvements are explored by hypothesizing interactions with sex and an interoceptive mechanism.

METHODS

In this naturalistic study, 87 hospitalized participants suffering from MDD completed questionnaires at pre- and post-treatment assessing multidimensional self-reported interoception (MAIA-2), somatic symptom burden (SCL-90-S® SOMA), and depression severity (BDI-II). We performed a multiple hierarchical regression analysis to test for interaction effects. The mediation hypothesis was path-analytically tested in a parallel mediation model by bootstrapping confidence intervals for (in)direct effects.

RESULTS

Improvements in self-reported interoception independently predicted positive treatment response, ΔR_adj²=8.61%, ΔF(8, 74) = 3.23, p < .01. Prediction effects were moderated by sex, ΔR_adj²=5.54%, ΔF(8, 66) = 2.22, p < .05. Post-hoc analyses revealed significant effects of body confidence in women, B = -4.26, t(28) = -2.78, p < .01, and of self-regulation in men, B = -3.21, t(17) = -2.27, p < .05. Effects of somatic symptom relief on treatment outcome were partially mediated by self-reported interoception, total indirect = 2.94 [95% BCa CI 0.99, 5.69].

CONCLUSION

Interoception patterns changed significantly and predicted outcome of hospital treatment in severely depressed patients. Our study could imply the need to consider body sensations additionally as a target for antidepressive treatments. The development of tailored interoceptive interventions in depressive patients represents a promising vision for the future.

Pump, person and Parfit: why the constitutive heart matters

The historical view of the heart as a source and repository of characteristics of individual persons remains prevalent in speech and literature. A more recent scientific view regards the heart as just a replaceable mechanical device, supporting a hydraulic system (the pump-view). To accept the pump-view is to reduce the historical view of the heart, and reference to it, to metaphor. To address whether this conclusion is justified, this paper investigates what constitutes an individual person over time and whether the heart has any role in that constitution. While some physical continuity may be necessary, most philosophers agree that our 'personal identity' is conferred through the persistence of 'psychological' characteristics predominantly through memory. Memory is constituted through the interplay of external and internal sensory experience-to which the heart is a major contributor. On scientific grounds alone this sensory role for the heart makes the pump-view incomplete. If our persistence as a person reflects the totality of experience codified through memory, and the heart is a central source of the internal component of that experience, then the pump-view is also misleading since the heart plays some constitutive role. More widely, if what fundamentally matters for our survival as persons is just psychological continuity, then the pump-view is irrelevant. While a 'supportive heart' may be necessary for continued embodiment, it is on the constitutive role of the heart, as part of a unique internal experience, that our individuation as persons depends.

An Active Inference Approach to Interoceptive Psychopathology

Interoception refers to the process by which the nervous system senses and integrates signals originating from within the body, providing a momentary mapping of the body's internal landscape and its relationship to the outside world. Active inference is based on the premise that afferent sensory input to the brain is constantly shaped and modified by prior expectations. In this review we propose that interoceptive psychopathology results from two primary interoceptive dysfunctions: First, individuals have abnormally strong expectations of the situations that elicit bodily change (i.e., hyperprecise priors), and second, they have great difficulty adjusting these expectations when the environment changes (i.e., context rigidity). Here we discuss how these dysfunctions potentially manifest in mental illness and how interventions aimed at altering interoceptive processing can help the brain create a more realistic model of its internal state.

Reduction of auditory input improves performance on the heartbeat tracking task, but does not necessarily enhance interoception

Previous research utilising a between-subjects design has indicated that the use of noise-dampening ear protectors might enhance interoceptive accuracy (IAcc). In the present study, we further examined this effect using a repeated-measures, within-participants design, and investigated potential mechanisms that might explain the effect. 50 participants completed the heartbeat tracking task (HTT) with and without the use of industrial ear protectors, in a counter-balanced order. Participants were asked to count the number of heartbeats occurring in five discrete time intervals of 25, 35, 45, 55 and 95 s, without feeling for a manual pulse. HTT scores were significantly higher when ear protectors were worn, and the improvement in performance was greatest for participants with lower baseline IAcc. The ear protectors were associated with significantly increased self-reported heartbeat audibility, task-related confidence and concentration, and decreased levels of distractibility. Heartbeat audibility was also correlated with HTT performance when the ear protectors were worn. Because the use of industrial ear defenders resulted in increased heartbeat audibility, this manipulation should not be used to assess causal hypotheses related to changes in IAcc. However, it may serve as a simple, non-invasive manipulation to assess the effects of 'externalised' interoceptive signals.

Altered interoceptive processing in smokers: Evidence from the heartbeat tracking task

Neuroimaging evidence suggests that interoceptive processing might be altered in nicotine addiction, however this has not yet been confirmed with behavioural measures. Therefore, we investigated the perception of internal bodily states in smokers (n = 49) and people who had never smoked (n = 51), by measuring interoceptive accuracy (IAcc) and interoceptive sensibility (IS). IAcc was measured with a heartbeat tracking task and a heartbeat discrimination task. Performance on the heartbeat tracking task may be influenced by one's ability to estimate an elapsed time interval so this was controlled by also administering a time-estimation (TE) task. IS was measured using two sub-scales from the Multidimensional Assessment of Interoceptive Awareness (MAIA). All smokers completed the Revised Fagerström Test for Nicotine Dependence (FTND-R) to measure addiction severity. Non-smokers performed significantly better than smokers on the heartbeat tracking task. There were no significant group differences observed for the remaining variables. Furthermore, none of the variables predicted addiction severity. This is the first demonstration of behavioural differences in interoception between smokers and non-smokers.