The sense of owning one's body is essential for distinguishing internal from external sensations. Research using bodily illusions shows that this sense depends on integrating visual, tactile and proprioceptive signals, yet the role of multisensory predictions remains unclear. We addressed this using a modified rubber hand illusion. Two robotic arms tapped the two visible rubber hands, while a third arm simultaneously tapped the participant's hidden real hand. One rubber hand received synchronous stimulation, while the other was stimulated with varying temporal delays. Visual feedback was manipulated across three conditions: full view of the approaching probe and touch, occlusion of the approaching probe or occlusion of the touch event. Participants reported which rubber hand felt more like their own hand. Using signal detection analysis, we examined whether occluding predictive visual feedback influenced sensitivity to visuotactile synchrony, perceptual bias or both. Results showed that occluding the approaching probe did not reduce sensitivity to visuotactile signals; as long as the touch or its timing was visible or inferable, sensitivity remained stable. However, perceptual bias was reduced when predictive visual information was removed. These findings reveal how visually driven tactile predictions shape body ownership and highlight signal detection analysis as a useful tool to dissociate sensitivity and bias in self-perception.

The pleasantness perception of CT-optimal touch is usually assessed with subjective and explicit measures. As these can be prone to biases, it is important to develop implicit measures as well. The vestigial post-auricular muscle reflex (PAR) might be a good candidate, given its sensitivity to pleasant visual and auditory stimuli. As such, we investigated if the PAR can also be modulated by CT-optimal touch. We additionally compared how the PAR responds to social and robotic touch and conducted control experiments to replicate the reflex's specific sensitivity to primary rewards. The sample consisted of 43 non-clinical participants. PAR responses were recorded while participants were touched by an experimenter and a robot, with a velocity of 3 cm/s (CT-optimal touch) and 18 cm/s (CT non-optimal touch). After each trial, participants also subjectively rated the pleasantness of the touch. Although the results revealed that CT-optimal touch was subjectively perceived to be more pleasant than CT non-optimal touch, it did not result in a potentiation of the PAR. Interestingly, social touch was subjectively perceived to be more pleasant than robotic touch and potentiated the PAR. The control experiments confirmed that the PAR is particularly modulated by primary (food, erotica), and not secondary (adventure, cuteness, monetary) rewards. While additional research is needed to further investigate the relation between the PAR and CT-optimal touch, the current results do already suggest that this reflex responds to the primary reward value of social touch.

It has previously been shown that interpersonal trauma (IPT) can negatively impact the experience and perception of social touch. There are, however, also indications that people with IPT might simultaneously experience a stronger longing for touch (LFT). As this has not been systematically investigated, the aim of the current study was to assess the experience of LFT in people with IPT. We additionally assessed if LFT was associated with the perception of CT-optimal touch in this population. In Study 1, 122 women participated in an online experiment. Participants watched and rated videos of CT-optimal (3 cm/s) and CT non-optimal (18 cm/s) touch. They also filled out questionnaires about their LFT and general attitudes towards touch. In Study 2, 44 women participated in a lab-based experiment. Participants were touched by a female researcher with a brush and hand at CT-optimal (3 cm/s) and CT non-optimal (18 cm/s) speeds. They additionally filled out questionnaires about LFT and general attitudes towards touch. In contrast with our hypotheses, women with IPT did not report a stronger LFT or a more negative perception of CT-optimal touch in either study. There was also no significant association between LFT and the perception of touch in women with and without IPT. These non-significant results may be a consequence of the low prevalence of trauma-related psychopathology among participants with IPT in the current study. Implications of these results and suggestions for future research are discussed.

Previous studies have shown that the prevalence of longing for touch (LFT) is high, but little is known about the potential causes. In order to provide insights into this, the current study mapped the self-identified causes of LFT in a community sample. A total of 186 adults participated in the study. The prevalence of LFT was 76.3 %. Participants with LFT were asked to identify the causes by responding to thirteen closed items and one open question. The thirteen closed items were constructed based on literature and conversations with professionals. An exploratory factor analysis conducted on these thirteen items resulted in two factors: physical distance and internal barriers. In general, physical distance was a significantly more prominent self-identified cause than internal barriers. Interestingly, men were more likely to indicate that internal barriers were a cause of their LFT than women. These results provide the first insights into the potential causes of LFT. Future studies should focus on replicating these findings in larger and more diverse samples, as well as investigating which causes are most suitable targets for interventions.

Previous studies have reported an association between the COVID-19 pandemic, social distancing regulations and longing for touch (LFT; i.e., a discrepancy between actual touch frequency and one’s desire to be touched). However, less is known about the prevalence and severity of LFT in the general population in the absence of social distancing regulations. The aim of this study was therefore to exploratively compare data collected during and after the pandemic. Pandemic data was collected online in an international sample (n = 1982), of which a matched subsample (n = 115) was used in the reported analyses. Post-pandemic data was collected one week after social distancing regulations restrictions were lifted in the Netherlands (n = 60) and when virtually no restrictions were in place (n = 55). The severity of LFT was significantly higher during the pandemic than afterwards. Although there were no significant differences in the general prevalence of LFT, significantly more participants reported high levels of LFT (score of 75–100) during the pandemic. We cautiously conclude that, although LFT may have peaked during the pandemic, a large portion of the general population desires to experience more interpersonal touch, even in the absence of social distancing regulations.

BACKGROUND:Adolescence is a period marked by important physical and social changes, which often leads to an increase of body dissatisfaction. Recent studies have shown an association between interoception and body dissatisfaction in female adolescents. One variable that may contribute to the association between interoceptive awareness and body dissatisfaction is intolerance of uncertainty (IU). This study aims to investigate multiple facets of interoceptive awareness, IU, and their relations with body dissatisfaction in adolescent girls.METHODS:In a cross-sectional study, a convenience sample of 307 adolescent girls (mean age = 17.73; SD = 1.02) was recruited in the Netherlands in 2022. Three questionnaires were completed measuring interoceptive awareness, IU, and body dissatisfaction. A moderation analyses using a multiple hierarchical regression was used to investigate associations between variables.RESULTS:Correlation analyses indicated that several facets of lower interoceptive awareness (Not distracting, Not worrying and Trusting) were related to higher levels of body dissatisfaction. IU only marginally moderated the relationship between several domains of interoceptive awareness (Notice, Attention regulation and Emotional awareness) and body dissatisfaction.DISCUSSION:Findings suggest that experiencing bodily signals as ambiguous and uncertain may result in more complex body image issues. Within certain domains of interoceptive awareness, IU may affect the process of appraising bodily signals. Furthermore, adolescent girls who do not feel safe in their body and who find it difficult to distract their thoughts when experiencing pain or discomfort in their body may be particularly at risk for developing more complex body image disturbances and may benefit from interventions improving both interoceptive awareness and IU. Moreover, future research should focus on interoceptive awareness and IU as potential underlying mechanisms for body image issues.

To combat the spread of the COVID-19, regulations were introduced to limit physical interactions. This could induce a longing for touch in the general population and subsequently impact social, psychological, physical and environmental quality of life (QoL). The aim of this study was to investigate the potential association between COVID-19 regulations, longing for touch and QoL. A total of 1978 participants from different countries completed an online survey, including questions about their general wellbeing and the desire to be touched. In our sample, 83% of participants reported a longing for touch. Longing for touch was subsequently associated with a lower physical, psychological and social QoL. No association was found with environmental QoL. These findings highlight the importance of touch for QoL and suggest that the COVID-19 regulations have concurrent negative consequences for the wellbeing of the general population.

Interpersonal touch and affective touch play a crucial role in social interactions and have a positive influence on mental health. The social distancing regulations implemented during the COVID-19 pandemic have reduced the ability to engage in interpersonal touch. This could cause longing for touch, and it might subsequently alter the way in which affective touch is perceived. To investigate this, we conducted an online survey and included 1982 participants, which contained questions regarding the COVID-19 regulations, longing for touch, and the perceived pleasantness of affective and non-affective touch. Results showed that participants reported feelings of longing for touch. This significantly increased with the duration and severity of the COVID-19 regulations. In addition, participants who experienced more longing for touch rated videos of affective and non-affective touch as more pleasant. Current results provide insight in the impact of sudden and prolonged COVID-19 regulations and show that increasing the duration and severity of these regulations is associated with a higher desire for touch, which is associated with increased perceived pleasantness of observing touch.

Interpersonal touch and affective touch play a crucial role in social interactions and have a positive influence on mental health. The social distancing regulations related to the COVID-19 pandemic have reduced the ability to engage in interpersonal touch. This could cause touch deprivation, and it might alter the way in which affective touch is perceived. To investigate this, we conducted an online survey with 2348 participants, which contained questions regarding the COVID-19 regulations, touch deprivation and the perceived pleasantness of affective and non-affective touch. Results showed that participants reported feelings of touch deprivation. This significantly increased with the duration and severity of the COVID-19 regulations. Participants who experienced more touch deprivation rated videos of affective and non-affective touch as more pleasant. Current results provide insight in the impact of sudden and prolonged COVID-19 regulations and show that increasing the duration and severity of these regulations is associated with a higher desire for touch, which leads to increased perceived pleasantness of touch.

We aimed at investigating the contribution of sensory predictions triggered by the sight of an object moving towards the body for the sense of body ownership. We used a recently developed psychophysical discrimination task to assess body ownership in the rubber hand illusion. In this task, the participants had to choose which of the two right rubber hands in view felt most like their own, and the ownership discriminations were fitted to psychometric curves. In the current study, we occluded the visual impressions of the object moving towards one of the rubber hands (during the first two-thirds of the path) and only revealed the final third of the object's movement trajectory when it touched the rubber hand (approach-occluded condition). Alternatively, we occluded only the final part so that the main part of the movement towards the model hand was visible (touch-occluded). We compared these two conditions to an illusion baseline condition where the object was visible during the entire trajectory and contact (no-occlusion). The touch-occluded condition produced equally strong hand ownership as the baseline condition with no occlusion, while ownership perception was significantly reduced when vision of the object approaching the rubber hand was occluded (approach-occluded). Our results show that tactile predictions generated from seeing an object moving towards the body are temporally exact, and they contribute to the rubber hand illusion by integrating with temporally congruent afferent sensory signals. This finding highlights the importance of multisensory predictions in peripersonal space, object permanence, and the interplay between bottom-up sensory signals and top-down predictions in body ownership.

Although body size estimation (BSE) tasks are frequently used to investigate distorted body representation in anorexia nervosa (AN), the link between anxiety and task performance has been overlooked. To investigate this, 30 female healthy controls (HCs) and 29 female AN patients completed two body attitude questionnaires and three BSE tasks (the Visual Estimation Task, the Tactile Estimation Task and the Hoop Task). Participants completed two body attitude questionnaires and three BSE tasks; the Visual Estimation Task, the Tactile Estimation Task, and the Hoop Task. The STAI-6 was administered before and after each body-related task to assess state anxiety. Results showed that state anxiety levels increased significantly more in AN patients than in HC after completing each task. Thus, performance of AN patients on BSE and other body-related tasks might not just indicate the (mis)perception of their body but also co-occur with increased state anxiety. This has implications for the interpretation of these tasks and for furthering our understanding of the mechanisms that underlie distorted body image in AN.