Dr Jennifer Murphy

Interoceptive dimensions vary across not just individuals, but also groups. This chapter reviews the role of demographic variables in shaping interoception. In particular, the focus is on cultural, gender, and sex-based differences in objective interoceptive accuracy and outcomes associated with self-reported interoception. In terms of culture, the majority of existing literature centres on ethnic differences, particularly between East Asian and European-American groups. These studies suggest that while Western groups tend to show greater interoceptive accuracy, non-Western groups report more interoceptive attention. A similar pattern is seen for gender, with men showing greater interoceptive accuracy but reporting less interoceptive attention than women. Research into cultural and gender differences are in many ways complementary, as cultural differences can be gender-specific, and gender itself is a product of culture, with gender norms and roles varying across cultural groups. Culture, gender, and sex influence different dimensions of interoception and have widespread implications for emotion, neuroscience, and mental health. The development of measures of interoceptive accuracy beyond the cardiac domain, and questionnaire measures with strong cross-cultural validity, will allow for further examination of such differences across interoceptive dimensions and bodily domains, extending our understanding of demographic differences in interoception, and their causes and implications.

In this chapter, we provide a summary of the key themes covered in An Introduction to Interoception and outline the common future directions outlined across chapters.

This book provides a comprehensive overview and critical evaluation of the emerging and exciting topic of interoception – the perception of the body’s internal state. Interest in the topic has been driven by the observation that interoception appears to affect fundamental psychological processes and numerous physical and mental health conditions. In this book, the major authorities in the field present a discussion of the history of interoception, the neural basis of interoception, and the measurement and models of interoception conceptualization. This is followed by a consideration of the many domains that interoception appears to impact (including social and cognitive abilities and mental and physical health conditions) and differences across demographic groups. Interoception: A Comprehensive Guide also explores real world applications, including training for interoception, the modulation of interoception and the impact of such interventions, and future research directions.

Interoception, the processing of internal bodily sensations, is associated with various mental health conditions. In particular, anxiety is often considered to be the prototypical interoceptive disorder. However, empirical evidence is mixed, with meta-analytic work reporting no relationship between anxiety and cardiac interoceptive accuracy. Less explored, however, are the mixed results relating to anxiety and self-reported interoception. This meta-analysis of 71 studies explored the relationship between self-report measures of interoception and anxiety. Across 12 measures (20 subscales), anxiety was associated with increased negative evaluations of, frequency of, and sensitivity to, bodily signals. Anxiety was also associated with greater (negative) attention to bodily signals, and difficulties describing bodily signals and emotions. However, anxiety was not associated with the use of bodily signals to inform emotions (e.g., noticing emotionally induced bodily signals). Results are discussed considering the overlap between anxiety and interoception questionnaires, the lack of specificity of certain measures, and the potential confound of individual differences in questionnaire interpretation. We also discuss limitations of anxiety measures and the clinical relevance of findings.

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 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, though 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.

Considerable research has addressed whether the cognitive and neural representations recruited by faces are similar to those engaged by other types of visual stimuli. For example, research has examined the extent to which objects of expertise recruit holistic representation and engage the fusiform face area. Little is known, however, about the domain-specificity of the exemplar pooling processes thought to underlie the acquisition of familiarity with particular facial identities. In the present study we sought to compare observers' ability to learn facial identities and handwriting styles from exposure to multiple exemplars. Crucially, while handwritten words and faces differ considerably in their topographic form, both learning tasks share a common exemplar pooling component. In our first experiment, we find that typical observers' ability to learn facial identities and handwriting styles from exposure to multiple exemplars correlates closely. In our second experiment, we show that observers with Autism Spectrum Disorder (ASD) are impaired at both learning tasks. Our findings suggest that similar exemplar pooling processes are recruited when learning facial identities and handwriting styles. Models of exemplar pooling originally developed to explain face learning, may therefore offer valuable insights into exemplar pooling across a range of domains, extending beyond faces. Aberrant exemplar pooling, possibly resulting from structural differences in the inferior longitudinal fasciculus, may underlie difficulties recognising familiar faces often experienced by individuals with ASD, and leave observers overly reliant on local details present in particular exemplars.

Few findings in cognitive science have proved as influential as the composite face effect. When the top half of one face is aligned with the bottom half of another, and presented upright, the resulting composite arrangement induces a compelling percept of a novel facial configuration. Findings obtained using composite face procedures have contributed significantly to our understanding of holistic face processing, the detrimental effects of face inversion, the development of face perception, and aberrant face perception in clinical populations. Composite paradigms continue to advance our knowledge of face perception, as exemplified by their recent use for investigating the perceptual mechanisms underlying dynamic face processing. However, the paradigm has been the subject of intense scrutiny, particularly over the last decade, and there is a growing sense that the composite face illusion, whilst easy to illustrate, is deceptively difficult to measure and interpret. In this review, we provide a focussed overview of the existing composite face literature, and identify six priorities for future research. Addressing these gaps in our knowledge will aid the evaluation and refinement of theoretical accounts of the illusion.

Interoception, the perception of one?s internal state, is commonly quantified using the heartbeat counting task (HCT) ? which is thought to be a measure of cardiac interoceptive sensitivity (accuracy). Interoceptive sensitivity has been associated with a number of clinical traits and aspects of higher order cognition, including emotion processing and decision-making. It has been proposed that alexithymia (difficulties identifying and describing one?s own emotions) is associated with impaired interoceptive sensitivity, but new research questions this association. Problematically, much evidence attesting to the absence of this association has been conducted using the HCT, a measure affected by various physiological and psychological factors. Here, we present novel data (N=287) examining the relationship between alexithymia and HCT performance, controlling for a number of potential confounds. Inclusion of these control measures reveals the predicted negative relationship between alexithymia and HCT performance. Results are discussed with regard to difficulties quantifying interoceptive sensitivity using the HCT.

Interoception, the perception of the body's internal state, contributes to numerous aspects of higher-order cognition. Several theories suggest a causal role for atypical interoception in specific psychiatric disorders, including a recent claim that atypical interoception represents a transdiagnostic impairment across disorders characterized by reduced perception of one's own emotion (alexithymia). Such theories are supported predominantly by evidence from only one interoceptive domain (cardiac); however, evidence of domain-specific interoceptive ability highlights the need to assess interoception in noncardiac domains. Using novel interoceptive tasks, we demonstrate that individuals high in alexithymic traits show a reduced propensity to utilize interoceptive cues to gauge respiratory output (Experiment 1), reduced accuracy on tasks of muscular effort (Experiment 2), and taste sensitivity (Experiment 3), unrelated to any co-occurring autism, depression, or anxiety. Results suggest that alexithymia reflects a multidomain, multidimensional failure of interoception, which is consistent with theories suggesting that atypical interoception may underpin both symptom commonalities between psychiatric disorders and heterogeneity within disorders.

Symptoms of internalizing disorders such as depression and anxiety increase in adolescence, especially in females. However, gender differences in depression and anxiety symptoms emerge only after puberty onset. Levels of alexithymia, characterized by difficulties identifying and describing one's emotions, are elevated in depression and anxiety, and fluctuate across adolescence in a gender-specific manner. This study investigated changes in alexithymia across adolescence, and explored the potential role of alexithymia in the development of depression and anxiety, separately for females and males. Accordingly, 140 adolescents aged 11 to 21 years (77 female) completed self-report measures of alexithymia, depression and anxiety, and pubertal development. For females alone, pubertal maturation was associated with alexithymic traits (specifically difficulties identifying and describing feelings), as well as symptoms of depression and anxiety. After accounting for alexithymia, the relationship between puberty and depression and anxiety was absent or reduced in females. Thus, alexithymic traits may have differential consequences for males and females, and possibly contribute towards increased depression and anxiety symptoms in females during adolescence. We propose that developmental changes in alexithymia should be considered when studying the onset and development of internalizing psychological disorders during adolescence.

Interoception, perception of one’s bodily state, has been associated with mental health and socio-emotional processes. However, several interoception tasks are of questionable validity, meaning associations between interoception and other variables require confirmation with new measures. Here we describe the novel, smartphone-based Phase Adjustment Task (PAT). Tones are presented at the participant’s heart rate, but out of phase with heartbeats. Participants adjust the phase relationship between tones and heartbeats until they are synchronous. Data from 124 participants indicates variance in performance across participants which is not affected by physiological or strategic confounds. Associations between interoception and anxiety, depression and stress were not significant. Weak associations between interoception and mental health variables may be a consequence of testing a non-clinical sample. A second study revealed PAT performance to be moderately stable over one week, consistent with state effects on interoception.

The present study sought to determine whether contextual information available when viewing social interactions from third-person perspectives may influence observers' perception of the interactants' facial emotion. Observers judged whether the expression of a target face was happy or fearful, in the presence of a happy, aggressive, or neutral interactant. In 2 experiments, the same target expressions were judged to be happier when presented in the context of a happy interactant than when interacting with a neutral or aggressive partner. We failed to show that the target expression was judged as more fearful when interacting with an aggressive partner. Importantly, observers' perception of the target expression was not modulated by the emotion of the context interactant when the interactants were presented back-to-back, suggesting that the bias depends on the presence of an intact interaction arrangement. These results provide valuable insight into how social contextual effects shape our perception of facial emotion.

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.

In recent years, measures of cardiac interoceptive accuracy have been heavily scrutinised. The focus has been on potentially confounding physiological and psychological factors; little research has examined whether the device used to record objective heartbeats may influence cardiac interoceptive accuracy. The present studies assessed whether the device employed influences heartbeat counting (HCT) accuracy and the location from which heartbeats are perceived. In Study One, participants completed the HCT using a hard-clip finger pulse oximeter, electrocardiogram (ECG) and a smartphone application. In Study Two, an ECG, hard-clip and soft-clip oximeter were compared. Moderate-strong correlations were observed across devices, however, mean HCT accuracy and confidence varied as a function of device. Increased sensation in the finger when using a hard-clip pulse oximeter was related to increased accuracy relative to ECG. Results suggest that the device employed can influence HCT performance, and argue against comparing, or combining, scores obtained using different devices.

In recent years, there has been a significant rise in interest in interoception, the processing of internal bodily signals. This interest has been coupled by increased concerns regarding the measurement and conceptualisation of interoception. Focusing on cardiac interoceptive accuracy, I outline what I believe to be the most pressing issues in the field of interoception-specifically the continued reliance on the heartbeat counting task. I then provide an overview of what I believe to be more general limitations concerning how we measure and conceptualise individual differences in interoception and suggestions for a way forward. Specifically, I believe that by moving beyond single measurements, establishing optimal levels of interoceptive accuracy, and refocusing from accuracy to propensity, we may be able to uncover the real-life relevance of interoceptive abilities.

Differences in the visual processing of familiar and unfamiliar faces have prompted considerable interest in face learning, the process by which unfamiliar faces become familiar. Previous work indicates that face learning is determined in part by exposure duration; unsurprisingly, viewing faces for longer affords superior performance on subsequent recognition tests. However, there has been further speculation that exemplar variation, experience of different exemplars of the same facial identity, contributes to face learning independently of viewing time. Several leading accounts of face learning, including the averaging and pictorial coding models, predict an exemplar variation advantage. Nevertheless, the exemplar variation hypothesis currently lacks empirical support. The present study therefore sought to test this prediction by comparing the effects of unique exemplar face learning--a condition rich in exemplar variation--and repeated exemplar face learning--a condition that equates viewing time, but constrains exemplar variation. Crucially, observers who received unique exemplar learning displayed better recognition of novel exemplars of the learned identities at test, than observers in the repeated exemplar condition. These results have important theoretical and substantive implications for models of face learning and for approaches to face training in applied contexts.

Objective Interoception plays an important role in psychological functioning and mental and physical health. Recent studies have highlighted the need to distinguish between different aspects of interoception in self-report measures, including subjective interoceptive accuracy and attention. However, there is currently no questionnaire available in Chinese to measure either of these aspects, especially in patients with chronic pain conditions. This paper presents a Chinese translation of the Interoceptive Accuracy Scale (IAS; Murphy et al., 2020). Methods In three studies (N = 1166), we examined the factor structure and improved dimensionality of the Chinese IAS using factor analysis and item response theory models, compared its criterion validity in respondents with and without chronic pain, and examined its construct (convergent and discriminant) validity using network analysis approach. Results We demonstrated that the Chinese IAS is essentially unidimensional and developed a refined short form (IAS-SF) with improved unidimensionality. Both the Chinese IAS and IAS-SF showed comparable criterion validity in respondents with and without chronic pain, and both showed acceptable construct validity. Conclusion Overall, the Chinese IAS and Chinese IAS-SF will be useful tools for researchers and clinicians interested in interoceptive processes in Chinese populations or cross-cultural settings, especially in pain research.

Despite the heterogeneity in autism, socioemotional difficulties are often framed as universal. Increasing evidence, however, suggests that socioemotional difficulties may be explained by alexithymia, a distinct yet frequently co-occurring condition. If, as some propose, autistic traits are responsible for socioemotional impairments, then alexithymia may itself be a symptom of autism. We aimed to determine whether alexithymia should be considered a product of autism or regarded as a separate condition. Using factor-analytic and network approaches, we provide evidence that alexithymic and autistic traits are distinct. We argue that: (1) models of socioemotional processing in autism should conceptualise difficulties as intrinsic to alexithymia; and (2) assessment of alexithymia is crucial for diagnosis and personalised interventions.

Interoception concerns the perception of the body’s internal state. Despite the importance of this ability for health and aspects of higher-order cognition, its measurement remains problematic. Most studies of interoception employ one of two tasks: the heartbeat counting or heartbeat discrimination task. These tasks are thought to index common abilities, an assertion often used to justify the use of a single measure of cardiac interoception. However, mixed findings regarding the relationship between performance on these tasks raises the question of whether they can be used interchangeably to assess interoceptive accuracy, confidence and awareness (‘metacognition’). The present study employed a meta-analytical approach to assess the association between these tasks. Pooled findings from 22 studies revealed a small relationship between accuracy scores on the measures. Additional analyses demonstrated a moderate relationship between confidence ratings but no association between measures of interoceptive awareness. These findings question the interchangeable use of the two tasks.

Collaboration leads us to judge our own ability to be more similar to our collaborators and their ability to be more similar to our own, while competition leads us to exaggerate the gap between our abilities. How does this happen and what does it mean?

A decline in emotion recognition ability across the lifespan has been well documented. However, whether age predicts emotion recognition difficulties after accounting for potentially confounding factors which covary with age remains unclear. Although previous research suggested that age-related decline in emotion recognition ability may be partly a consequence of cognitive (fluid intelligence, processing speed) and affective (e.g., depression) factors, recent theories highlight a potential role for alexithymia (difficulty identifying and describing one's emotions) and interoception (perception of the body's internal state). This study therefore aimed to examine the recognition of anger and disgust across the adult lifespan in a group of 140 20-90-year-olds to see whether an effect of age would remain after controlling for a number of cognitive and affective factors potentially impacted by age. In addition, using an identity recognition control task, the study aimed to determine whether the factors accounting for the effects of age on emotion discrimination also contribute towards generalised face processing difficulties. Results revealed that discrimination of disgust and anger across the lifespan was predicted by processing speed and fluid intelligence, and negatively by depression. No effect of age was found after these factors were accounted for. Importantly, these effects were specific to emotion discrimination; only crystallised intelligence accounted for unique variance in identity discrimination. Contrary to expectations, although interoception and alexithymia were correlated with emotion discrimination abilities, these factors did not explain unique variance after accounting for other variables.

It has been suggested that individual differences in interoception (the perception of the body's internal state) can be divided into three distinct dimensions: interoceptive accuracy (performance on objective tests of interoceptive accuracy), interoceptive sensibility (self-reported beliefs concerning one's own interoception) and interoceptive awareness (a metacognitive measure indexed by the correspondence between interoceptive accuracy and interoceptive sensibility). Research conducted under this model underscores the importance of interoceptive awareness for a variety of disorder-specific and transdiagnostic symptoms. However, the clinical importance of interoceptive awareness means that this aspect of interoception warrants further scrutiny, and such scrutiny suggests that revision of the three-dimensional model of interoception is necessary. In this theoretical paper, we outline such a revision, highlighting a need to distinguish not only how interoception is measured (objective measures vs. self-report), but also what is measured (accuracy vs. attention). The model refines how individual differences in interoception are categorised, with important consequences for the measurement of interoceptive awareness. Such a revision may help researchers to identify the strengths and weaknesses in interoception observed across clinical conditions, and to isolate clinically relevant individual differences.

Most theories of emotion describe a crucial role for interoceptive accuracy, the perception of the body’s internal physiological signals, in emotional experience. Despite support for interoceptive accuracy’s role in emotion, findings of gender differences in emotional and interoceptive processing are incompatible with theory; women typically show poorer interoceptive accuracy, but women often outperform men on measures of emotional processing and recognition. This suggests a need to re-evaluate the relationship between interoceptive accuracy and emotion considering sex and gender. Here we extend Pennebaker and Roberts’ (1992) theory of gender differences in the use of interoceptive signals for emotional experience, proposing that language socialisation may result in gender differences in the propensity to label internal state changes as physiological or emotional, respectively. Despite outstanding questions concerning the fractionation of interoceptive and emotional domains, this theory provides a plausible explanation for seemingly incompatible findings of gender differences in interoceptive and emotional abilities.

Models of interoception highlight the importance of considering participants’ beliefs regarding their interoceptive ability. Research focusing on such beliefs suggests a dissociation between self-reported interoceptive accuracy and attention. However, it remains unclear whether such dissociations are driven by differences in the sensations rated across these questionnaires, or a genuine dissociation between different facets of self-reported interoception. Here we examined the relationship between self-report measures of interoceptive accuracy and attention using a novel measure– the Interoceptive Attention Scale– designed to match the interoceptive sensations included in an existing questionnaire measure of interoceptive accuracy. In addition, we examined whether the interpretation of questionnaire measures of interoception altered associations across measures. Results support the proposed distinction between self-reported interoceptive attention and accuracy and highlight the importance of considering the interpretation of questionnaire measures of interoception. The implications of these findings for theory, future research, and interpretation of existing research are discussed.

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.

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. •The Phase Adjustment Task (PAT) is tolerable in a fibromyalgia (FMS) sample.•FMS sample more likely to be classed as interoceptive on the PAT than pain-free sample.•FMS sample had higher self-reported interoception than pain-free sample.•FMS participants with high interoceptive accuracy had lower symptom impact.•Self-reported interoception positively correlated with FMS symptom severity and impact.

When upper and lower regions from different emotionless faces are aligned to form a facial composite, observers ‘fuse’ the two halves together, perceptually. The illusory distortion induced by task-irrelevant (‘distractor’) halves hinders participants' judgements about task-relevant (‘target’) halves. This composite-face effect reveals a tendency to integrate feature information from disparate regions of intact upright faces, consistent with theories of holistic face processing. However, observers frequently perceive emotion in ostensibly neutral faces, contrary to the intentions of experimenters. This study sought to determine whether this ‘perceived emotion’ influences the composite-face effect. In our first experiment, we confirmed that the composite effect grows stronger as the strength of distractor emotion increased. Critically, effects of distractor emotion were induced by weak emotion intensities, and were incidental insofar as emotion cues hindered image matching, not emotion labelling per se. In Experiment 2, we found a correlation between the presence of perceived emotion in a set of ostensibly neutral distractor regions sourced from commonly used face databases, and the strength of illusory distortion they induced. In Experiment 3, participants completed a sequential matching composite task in which half of the distractor regions were rated high and low for perceived emotion, respectively. Significantly stronger composite effects were induced by the high-emotion distractor halves. These convergent results suggest that perceived emotion increases the strength of the composite-face effect induced by supposedly emotionless faces. These findings have important implications for the study of holistic face processing in typical and atypical populations.

Desmedt et al. (2023) audit measures of interoceptive accuracy, the perception of internal bodily signals. Whilst a useful overview of tasks and limitations, as well as practical challenges, the authors 1) do not differentiate tasks of interoceptive propensity and accuracy, and 2) present critiques that we believe overlook the nuance of promising tasks. Interoceptive accuracy is defined as accuracy of the perception of internal bodily states. It is assessed by comparing participant reports to an objective measure (Murphy, 2023). Whilst individuals can differ with respect to interoception in many ways (Murphy, 2023), one neglected area is propensity to use internal signals (Murphy, 2022). As outlined by Murphy (2022), individuals differ in the cues they use to gauge internal states (e.g., hunger); some rely more on internal information (e.g., internal feelings of hunger), others on external information (e.g., time of day). Evidence that propensity is distinct from accuracy comes from examining gender (Murphy, 2022); although males typically outperform females on lab-based interoceptive accuracy tasks, women have a greater propensity to use external cues, resulting in comparable performance in real-life.

A range of processes are required for recognizing others' affective states. It is particularly important that we process the perceptual cues providing information about these states. These experiments tested the hypothesis that difficulties with affective state identification in older adults (OAs) arise, at least partly, from deficits in perceptual processing. To this end we presented "point light display" whole body stimuli to healthy OAs and comparison younger adults (YAs) in 3 signal detection experiments. We examined the ability of OAs to recognize visual bodily information-posture and kinematics-and whether impaired recognition of affective states can be explained by deficits in processing these cues. OAs exhibited reduced sensitivity to postural cues (Experiment 1) but not to kinematic cues (Experiment 2) in affectively neutral stimuli. Importantly, they also exhibited reduced sensitivity only to affective states conveyed predominantly through posture (Experiment 3) -that is, the cue they were impaired in perceiving. These findings highlight how affective state identification difficulties in OAs may arise from problems in perceptual processing and demonstrate more widely how it is essential to consider the contribution of perceptual processes to emotion recognition.

Background: Behavioral mitigation strategies to slow the spread of COVID-19 have resulted in sweeping lifestyle changes, with short-and long-term psychological, well-being, and quality of life implications. The Attitudes About COVID-19 and Health (ATTACH) study focuses on understanding attitudes and beliefs while considering the impact on mental and physical health and the influence of broader demographic and geographic factors on attitudes, beliefs, and mental health burden. Objective: In this assessment of our first wave of data collection, we provide baseline cohort description of the ATTACH study participants in the United Kingdom, the United States, and Mexico. Additionally, we assess responses to daily poll questions related to COVID-19 and conduct a cross-sectional analysis of baseline assessments collected in the UK between June 26 and October 31, 2020. Methods: The ATTACH study uses smartphone app technology and online survey data collection. Participants completed poll questions related to COVID-19 2 times daily and a monthly survey assessing mental health, social isolation, physical health, and quality of life. Poll question responses were graphed using 95% Clopper-Pearson (exact) tests with 95% CIs. Pearson correlations, hierarchical linear regression analyses, and generalized linear models assessed relationships, predictors of self-reported outcomes, and group differences, respectively. Results: By October 31, 2020, 1405, 80, and 90 participants had consented to participate in the UK, United States, and Mexico, respectively. Descriptive data for the UK daily poll questions indicated that participants generally followed social distancing measures, but worry and negative impacts on families increased as the pandemic progressed. Although participants generally reported feeling that the reasons for current measures had been made clear, there was low trust that the government was doing everything in its power to meet public needs. In the UK, 1282 participants also completed a monthly survey (94.99% [1326/1396] White, 72.22% [1014/1404] female, and 20.12% [277/1377] key or essential workers); 18.88% (242/1282) of UK participants reported a preexisting mental health disorder, 31.36% (402/1282) reported a preexisting chronic medical illness, and 35.11% (493/1404) were aged over 65; 57.72% (740/1282) of participants reported being more sedentary since the pandemic began, and 41.89% (537/1282) reported reduced access to medical care. Those with poorer mental health outcomes lived in more deprived neighborhoods, in larger households (Ps

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.

In their paper Suksasilp and Garfinkel (2022) outline the most comprehensive model of interoception to date. The authors expertly articulate the structure of interoception and their model incorporates multiple important facets. Despite many strengths, this model does not yet incorporate propensity to use interoceptive signals. Individuals differ in the degree to which they utilise interoceptive signals for gauging internal states and for higher-order cognitive processes. One example of this comes from gender differences in interoception; whilst men outperform women on lab-based tasks of interoceptive accuracy, no differences are observed in naturalistic environments where external cues are available for compensation (Cox et al., 1985, Pennebaker and Watson, 1988). Gender differences in the relationship between interoceptive accuracy and emotional processing are also reported, with evidence that emotional processing more strongly relates to interoception in men (Pennebaker and Roberts, 1992, Lischke et al., 2020). Given theoretical and empirical links between interoception emotion (Critchley & Garfinkel, 2017), these results are surprising as women generally outperform men on tests of emotion (Thompson & Voyer, 2014). Taken together, I propose that these results suggest that individuals differ in 1) their general interoceptive propensity (the use of internal vs. external cues for gauging internal states); 2) how much they rely upon interoceptive signals for different processes, such as emotional processing or decision making and; 3) the extent to which using interoceptive cues is adaptive.

Interoceptive accuracy, the ability to correctly perceive internal signals arising from the body, is thought to be disrupted in numerous mental and physical health conditions. Whilst evidence suggests poorer interoceptive accuracy in females compared to males, raising the possibility that interoceptive differences may relate to sex differences in mental and physical health, results concerning sex differences in interoceptive accuracy are mixed. Given such ambiguity, this meta-analysis aimed to establish the presence or absence of sex differences in interoceptive accuracy across cardiac, respiratory, and gastric domains. A review of 7956 abstracts resulted in 93 eligible studies. Results demonstrated superior accuracy in males across cardiac, but not gastric, tasks, while findings on respiratory tasks were mixed. Effect sizes were consistent across cardiac tasks, but instability and/or moderate heterogeneity was observed across other domains, likely due to the small number of eligible studies. Despite such limitations, results indicate the possibility of sex differences across interoception tasks and domains. Methodological limitations concerning the influence of physiological factors, and directions for future research are discussed.

Autistic traits are over-represented in transgender populations, and gender variance is high in autistic individuals. Furthermore, some evidence suggests that the autism/transgender overlap is limited to individuals sex assigned female. Few studies, however, have investigated the impact of this overlap on mental health. This study therefore sought to investigate whether the autism/transgender overlap confers an increased risk of depression or anxiety. An online study of 727 individuals revealed a substantial overlap between transgender identity and autism, with increased autistic traits found in trans men compared to trans women. Depression and anxiety were highest in autistic-trans individuals, but no superadditive effect was observed. The implications of these findings are discussed in relation to the wider healthcare system.

Fast Periodic Visual Stimulation (FPVS) with oddball stimuli has been used to investigate discrimination of facial identity and emotion, with studies concluding that oddball responses indicate discrimination of faces at the conceptual level (i.e., discrimination of identity and emotion), rather than low-level perceptual (visual, image-based) discrimination. However, because previous studies have utilised identical images as base stimuli, physical differences between base and oddball stimuli, rather than recognition of identity or emotion, may have been responsible for oddball responses. This study tested two new FPVS paradigms designed to distinguish recognition of expressions of emotion from detection of visual change from the base stream. In both paradigms, the oddball emotional expression was different from that of the base stream images. However, in the ‘fixed-emotion’ paradigm, stimulus image varied at every presentation but the emotion in the base stream remained constant, and in the ‘mixed-emotions’ paradigm, both stimulus image and emotion varied at every presentation, with only the oddball emotion (disgust) remaining constant. In the fixed-emotion paradigm, typical inversion effects were observed at occipital sites. In the mixed-emotions paradigm, however, inversion effects in a central cluster (indicative of higher level emotion processing) were present in typical participants, but not those with alexithymia (who are impaired at emotion recognition), suggesting that only the mixed-emotions paradigm reflects emotion recognition rather than detection of a lower-level visual change from baseline. These results have significant methodological implications for future FPVS studies (of both facial emotion and identity), suggesting that it is crucial to vary base stimuli sufficiently, such that simple physical differences between base and oddball stimuli cannot give rise to neural oddball responses.

Significant comorbidity has been demonstrated between feeding and eating disorders and autism. Atypical interoception (perception of bodily signals) may, at least in part, be responsible for this association, as it has been implicated in the aetiology of both conditions. However, significant methodological limitations are impeding progress in this area. This paper provides a brief overview of how interoception has been linked to autism and feeding and eating disorders in both adolescent and adult populations before identifying several issues with current measures of interoception. We suggest that methodological issues may be contributing to the inconsistency in the empirical literature, and provide suggestions for future research.

The Heartbeat Evoked Potential (HEP) has been proposed as a neurophysiological marker of interoceptive processing. Despite its use to validate interoceptive measures and to assess interoceptive functioning in clinical groups, the empirical evidence for a relationship between HEP amplitude and interoceptive processing, including measures of such processing, is scattered across several studies with varied designs. The aim of this systematic review and meta-analysis was to examine the body of HEP-interoception research, and consider the associations the HEP shows with various direct and indirect measures of interoception, and how it is affected by manipulations of interoceptive processing. Specifically, we assessed the effect on HEP amplitude of manipulating attention to the heartbeat; manipulating participants’ arousal; the association between the HEP and behavioural measures of cardiac interoception; and comparisons between healthy and clinical groups. Following database searches and screening, 45 studies were included in the systematic review and 42 in the meta-analyses. We noted variations in the ways individual studies have attempted to address key confounds, particularly the cardiac field artefact. Meta-analytic summaries indicated there were moderate to large effects of attention, arousal, and clinical status on the HEP, and a moderate association between HEP amplitude and behavioural measures of interoception. Problematically, the reliability of the meta-analytic effects documented here remain unknown, given the lack of standardised protocols for measuring the HEP. Thus, it is possible effects are driven by confounds such as cardiac factors or somatosensory effects.

Interoceptive accuracy is frequently assessed using the Heartbeat Counting Task (HCT), requiring participants to count the number of times their heart beats. The HCT validity has been questioned, as participants may perform the task by estimating, rather than counting, their felt heartbeats. Participants could estimate the time or use their knowledge of their heart rate. Some research ruled out the contribution of time estimation in HCT performance. However, we believe these studies relied on a problematic analytic rationale. We revisited this question by relying on new analytic strategies, and by examining the role of estimation in HCT performance, while varying task instructions. The findings support the role of time and knowledge-based estimations under original instructions. They also highlight the critical impact of instructions on HCT validity. Given the many limitations of the HCT, we urge researchers to test the robustness of published effects and to reconsider the interpretation of replicable results.

Anxiety is often conceptualised as the prototypical disorder of interoception (one's perception of bodily states). Whilst theoretical models predict an association between interoceptive accuracy and anxiety, empirical work has produced mixed results. This manuscript presents a pre-registered systematic review (https://osf.io/2h5xz) and meta-analysis of 55 studies, obtained via a Pubmed search on 9th November 2020, examining the relationship between state and trait anxiety and objectively measured cardiac interoceptive accuracy as assessed by heartbeat counting and discrimination tasks. Potential moderators of this relationship - the age, gender and clinical diagnoses of participants, the anxiety measures used and the study design - were also explored. Overall, we found no evidence for an association between cardiac interoceptive accuracy and anxiety, with none of the factors examined moderating this finding. We discuss the implications these findings have for future research, with a particular focus on the need for further investigation of the relationship between anxiety and other facets of interoception.

Various aspects of physical and mental health have been linked to an individual's ability to perceive the physical condition of their body ('interoception'). In addition, numerous studies have demonstrated a role for interoception in higher-order cognitive abilities such as decision-making and emotion processing. The importance of interoception for health and typical cognitive functioning has prompted interest in how interoception varies over the lifespan. However, few studies have investigated interoception into older adulthood, and no studies account for the set of physiological changes that may influence task performance. The present study examined interoception from young to very late adulthood (until 90 years of age) utilising a self-report measure of interoception (Study One) and an objective measure of cardiac interoception (Study Two). Across both studies, interoception decreased with age, and changes in interoceptive accuracy were observed which were not explained by accompanying physiological changes. In addition to a direct effect of age on interoception, an indirect effect of ageing on cardiac interoceptive accuracy mediated by body mass index (BMI) was found, such that ageing was associated with increased BMI which was, in turn, associated with reduced interoceptive accuracy. Such findings support and extend previous research demonstrating interoceptive decline with advancing age, and highlight the importance of assessing whether decreasing interoceptive ability is responsible for some aspects of age-related ill-health and cognitive impairment.

According to predictive processing theories, emotional inference involves simultaneously minimising discrepancies between predictions and sensory evidence relating to both one's own and others' states, achievable by altering either one's own state (empathy) or perception of another's state (egocentric bias) so they are more congruent. We tested a key hypothesis of these accounts, that predictions are weighted in inference according to their precision (inverse variance). If correct, increasingly precise self-related predictions should be associated with increasingly biased perception of another's emotional expression. We manipulated predictions about upcoming own-pain (low or high magnitude) using cues that afforded either precise (a narrow range of possible magnitudes) or imprecise (a wide range) predictions. Participants judged pained facial expressions presented concurrently with own-pain to be more intense when own-pain was greater, and precise cues increased this biasing effect. Implications of conceptualising interpersonal influence in terms of predictive processing are discussed.

Faces are notoriously hard to perceive when turned upside-down. It is often claimed that perceptual decrements reflect a qualitative switch from parallel whole-face processing, to a serial analysis of individual features. To test this view, we examined observers' ability to categorize faces presented in their entirety, or viewed through a dynamic aperture that moved incrementally across the facial image. Exposing faces region-by-region disrupts holistic processing, but permits serial analysis of local features. In line with the holistic accounts, we predicted that aperture viewing would greatly impair judgements of upright, but not inverted faces. As expected, identity, gender, age, and expression were categorized more precisely when faces were presented upright and in their entirety. Contrary to holistic accounts, however, the detrimental effects of inversion seen in the whole-face condition were no greater than in the aperture condition. Moreover, we found comparable aperture effects for upright and inverted faces; observers exhibited less decision noise when faces were viewed in their entirety, than when viewed through the aperture, irrespective of orientation. We replicate these findings in control experiments and show that the same pattern is seen irrespective of the direction of aperture transition or the nature of the fill used to replace the occluded regions of the to-be-judged image. These results challenge holistic accounts of the face inversion effect and support an alternative interpretation. First, in line with previous findings, they indicate that perceptual decrements when viewing upside-down faces result from impoverished descriptions of local regions, not the loss of whole-face processing. Second, when interpreting inverted faces, access to the wider face context appears to be far more important than currently believed. (C) 2017 The Authors. Published by Elsevier B.V.

It has recently been proposed that measures of the perception of the state of one’s own body (“interoception”) can be categorised as one of several types depending on both how an assessment is obtained (objective measurement vs. self-report) and what is assessed (degree of interoceptive attention vs. accuracy of interoceptive perception). Under this model, a distinction is made between beliefs regarding the degree to which interoceptive signals are the object of attention and beliefs regarding one’s ability to perceive accurately interoceptive signals. This distinction is difficult to test, however, because of the paucity of measures designed to assess self-reported perception of one’s own interoceptive accuracy. This article therefore reports on the development of such a measure, the Interoceptive Accuracy Scale (IAS). Use of this measure enables assessment of the proposed distinction between beliefs regarding attention to, and accuracy in perceiving, interoceptive signals. Across six studies, we report on the development of the IAS and, importantly, its relationship with measures of trait self-reported interoceptive attention, objective interoceptive accuracy, confidence in the accuracy of specific interoceptive percepts, and metacognition with respect to interoceptive accuracy. Results support the distinction between individual differences in perceived attention towards interoceptive information and the accuracy of interoceptive perception.

Background Adolescence is a period of heightened vulnerability to developing mental health problems, and rates of mental health disorder in this age group have increased in the last decade. Preventing mental health problems developing before they become entrenched, particularly in adolescents who are at high risk, is an important research and clinical target. Here, we report the protocol for the trial of the ‘Building Resilience through Socioemotional Training’ (ReSET) intervention. ReSET is a new, preventative intervention that incorporates individual-based emotional training techniques and group-based social and communication skills training. We take a transdiagnostic approach, focusing on emotion processing and social mechanisms implicated in the onset and maintenance of various forms of psychopathology. Methods A cluster randomised allocation design is adopted with randomisation at the school year level. Five-hundred and forty adolescents (aged 12–14) will be randomised to either receive the intervention or not (passive control). The intervention is comprised of weekly sessions over an 8-week period, supplemented by two individual sessions. The primary outcomes, psychopathology symptoms and mental wellbeing, will be assessed pre- and post-intervention, and at a 1-year follow-up. Secondary outcomes are task-based assessments of emotion processing, social network data based on peer nominations, and subjective ratings of social relationships. These measures will be taken at baseline, post-intervention and 1-year follow-up. A subgroup of participants and stakeholders will be invited to take part in focus groups to assess the acceptability of the intervention. Discussion This project adopts a theory-based approach to the development of a new intervention designed to target the close connections between young people’s emotions and their interpersonal relationships. By embedding the intervention within a school setting and using a cluster-randomised design, we aim to develop and test a feasible, scalable intervention to prevent the onset of psychopathology in adolescence. Trial registration ISRCTN88585916. Trial registration date: 20/04/2023.

•Findings are mixed regarding the link between theory of mind (ToM) and alexithymia.•We provide a taxonomy of ToM measures and their relationship with alexithymia.•Alexithymia relates to poor ToM where tasks involve emotion recognition.•Alexithymia may also relate to a reduced propensity to engage in ToM.•This review highlights a need to consider the processes quantified by ToM tasks. Theory of Mind (ToM), the ability to represent the mental states of oneself and others, is an essential social skill disrupted across many psychiatric conditions. The transdiagnostic nature of ToM impairment means it is plausible that ToM impairment is related to alexithymia (difficulties identifying and describing one’s own emotions), as alexithymia is seen across psychiatric conditions. Whilst many studies have examined links between alexithymia and ToM, results are mixed. Therefore, the purpose of this systematic review is to provide a taxonomy of ToM tests and assess their relationship with alexithymia. Tests are grouped according to whether they assess propensity to engage spontaneously in ToM or accuracy of ToM inferences, with tests further subdivided into those that do, and do not, require emotion recognition. A review of 63 suitable studies suggests that alexithymia is often associated with reduced ToM, and inaccurate ToM when tasks require emotion recognition. This latter finding appears due to impaired emotion recognition, rather than ToM impairment per se. Further directions and considerations for future research are discussed.

Alexithymia, including the inability to identify and express one's own feelings, is a subclinical condition responsible for some of the socioemotional symptoms seen across a range of psychiatric conditions. The language hypothesis of alexithymia posits a language-mediated disruption in the development of discrete emotion con-cepts from ambiguous affective states, exacerbating the risk of developing alexithymia in language-impaired individuals. To provide a critical evaluation, a systematic review and meta-analysis of 29 empirical studies of language functioning in alexithymia was performed. A modest association was found between alexithymia and multi-domain language deficits (r =-0.14), including structural language, pragmatics, and propensity to use emotional language. A more theoretically-relevant subsample analysis comparing alexithymia levels in language -impaired and typical individuals revealed larger effects, but a limited number of studies adopted this approach. A synthesis of 11 emotional granularity studies also found an association between alexithymia and reduced emotional granularity (r =-0.10). Language impairments seem to increase the risk of alexithymia. Heteroge-neous samples and methods suggest the need for studies with improved alexithymia assessments.

Evidence suggests that intelligence is positively associated with performance on the heartbeat counting task (HCT). The HCT is often employed as measure of interoception - the ability to perceive the internal state of one's body - however it's use remains controversial as performance on the HCT is strongly influenced by knowledge of resting heart rate. This raises the possibility that heart rate knowledge may mediate the previously-observed association between intelligence and HCT performance. Study One demonstrates an association between intelligence and HCT performance (N = 94), and Study Two demonstrates that this relationship is mediated by knowledge of the average resting heart rate (N = 134). These data underscore the need to account for the influence of prior knowledge and beliefs when examining individual differences in cardiac interoceptive accuracy using the HCT.

Upright faces are thought to engage holistic processing whereby local regions are integrated into a unified whole for the purposes of rapid, efficient analysis. In contrast, inverted faces are thought to recruit a slower, less-accurate serial analysis of local features. Aperture paradigms, whereby a target face is revealed by a dynamic viewing window that shifts over the stimulus image, offer a compelling test of this view. If upright faces are processed holistically, perceptual judgements ought to be substantially disrupted when stimuli are viewed through apertures. In contrast, aperture viewing should produce little or no decrement in perceptual decisions when judging inverted faces, as they are thought to be subjected to serial feature-based analysis. Here we present four experiments that elucidate the effects of aperture viewing on the perception of upright and inverted faces. In our first two experiments, we find evidence of disproportionate aperture effects for upright faces relative to inverted faces. However, these findings are qualified by the fact that observers found it harder to discriminate inverted faces presented in the ‘baseline’ whole-face condition. When observers’ ability to discriminate faces in the whole-face condition was matched for difficulty (Experiments 3 and 4), we show that upright and inverted faces produce very similar aperture effects. These findings indicate that both upright and inverted faces benefit from whole-face processing and accord with other lines of evidence that faces engage qualitatively similar types of processing in both orientations.

There is growing interest in interoception, the perception of the body’s internal state, and its relevance for health across development. Most evidence linking interoception to health has used the heartbeat counting task. However, the temporal stability of the measure, particularly during childhood, and the etiological factors that underlie stability, remain largely unexamined. Using data from the ECHO twin sample we estimated the magnitude of genetic and environmental influences on the stability of heartbeat counting across two years (age 8–10), the longest time-frame examined. Heartbeat counting accuracy was modestly correlated across time, (r = .35) and accuracy improved with age. Non-shared environmental factors accounted for the most variance at both time points and were the main contributors to temporal stability of heartbeat counting. Future research should seek to identify these non-shared environmental factors and elucidate whether this relatively modest stability reflects variability of interoception across development or unreliability of the heartbeat counting task.

Disrupted sleep is a transdiagnostic factor characterising a multitude of psychiatric conditions. Although this is well-recognised, the cause of poor sleep across conditions is unclear. One possibility is that poor sleep is driven by traits which also co-occur with multiple conditions. Previous research suggests that alexithymia (an inability to identify and describe one's emotions) is a candidate trait, as it is linked to poor sleep quality and elevated levels of alexithymia are seen across multiple diagnostic groups. The association between alexithymia and poor sleep quality has been questioned however, with studies arguing that it is depression and anxiety, rather than alexithymia, which impact sleep quality. Problematically, such studies typically utilise measures of depression and anxiety which include items relating to sleep – meaning that apparent associations between depression and anxiety may be due to measurement issues, rather than to depression and anxiety per se. Study 1 confirmed the relationship between alexithymia and subjective sleep quality, whilst Study 2 utilised an independent sample to replicate the association between alexithymia and sleep quality, and to demonstrate that it is not a product of co-occurring depression or anxiety. Results therefore support the suggestion that alexithymia may explain disrupted sleep across multiple psychiatric conditions.

Interoception refers to the perception of the physiological condition of the body, including hunger, temperature, and heart rate. There is a growing appreciation that interoception is integral to higher-order cognition. Indeed, existing research indicates an association between low interoceptive sensitivity and alexithymia (a difficulty identifying one's own emotion), underscoring the link between bodily and emotional awareness. Despite this appreciation, the developmental trajectory of interoception across the lifespan remains under-researched, with clear gaps in our understanding. This qualitative review and opinion paper provides a brief overview of interoception, discussing its relevance for developmental psychopathology, and highlighting measurement issues, before surveying the available work on interoception across four stages of development: infancy, childhood, adolescence and late adulthood. Where gaps in the literature addressing the development of interoception exist, we draw upon the association between alexithymia and interoception, using alexithymia as a possible marker of atypical interoception. Evidence indicates that interoceptive ability varies across development, and that this variance correlates with established age-related changes in cognition and with risk periods for the development of psychopathology. We suggest a theory within which atypical interoception underlies the onset of psychopathology and risky behaviour in adolescence, and the decreased socio-emotional competence observed in late adulthood.

Sex differences in the prevalence and presentation of mental illnesses are well documented. Women are more likely to experience common mental health disorders (e.g., anxiety and depression), and when they experience these conditions, they often present differently to men (e.g., women are more likely to report somatic complaints). Periods of physical and hormonal change (e.g., adolescence, pregnancy, and menopause) are particular risk periods for the development of mental illness in women. In this article, we advance the proposal that interoception (the perception of the body's internal state) is one mechanism that might explain sex differences in vulnerability to mental illness. We argue that known sex differences in interoception, whereby women, compared to men, report heightened attention to internal signals coupled with worse interoceptive accuracy, may result from the increased amount of physical and hormonal change women experience across development. Given links between interoception and mental health, we propose that sex differences in interoception may partly explain sex differences in the prevalence and presentation of certain mental illnesses. Further scrutiny of this proposal may aid our understanding of sex differences in mental illness with implications for assessment, early intervention, and the development of novel treatment approaches.