Active Interpersonal Touch Gives Rise to the Social Softness Illusion

Summary Social touch plays a powerful role in human life, with important physical and mental health benefits in development and adulthood. Touch is central in building the foundations of social interaction, attachment, and cognition [1-5], and early, social touch has unique, beneficial neurophysiological and epigenetic effects [6-9]. The recent discovery of a separate neurophysiological system for affectively laden touch in humans has further kindled scientific interest in the area [10, 11]. Remarkably, however, little is known about what motivates and sustains the human tendency to touch others in a pro-social manner. Given the importance of social touch, we hypothesized that active stroking elicits more sensory pleasure when touching others' skin than when touching one's own skin. In a set of six experiments (total N = 133) we found that healthy participants, mostly tested in pairs to account for any objective differences in skin softness, consistently judged another's skin as feeling softer and smoother than their own skin. We further found that this softness illusion appeared selectively when the touch activated a neurophysiological system for affective touch in the receiver. We conclude that this sensory illusion underlies a novel, bodily mechanism of socio-affective bonding and enhances our motivation to touch others

Dissociation in How Core Autism Features Relate to Interoceptive Dimensions: Evidence from Cardiac Awareness in Children

Interoception in autism is receiving increasing research attention. Previously, differences were identified in autism on both objective and subjective measures of interoception, and an association with anxiety. Yet, it is currently unknown how interoception relates to core autism features. Here, in 49 autistic children, we consider how interoceptive accuracy (measured with heartbeat detection tasks) and sensibility (subjective judgements of awareness) relate to overall severity on the Autism Diagnostic Observation Schedule, and symptom domains of social-affective and repetitive, restricted behaviors. Socio-affective features were related to interoceptive sensibility, while repetitive restricted behaviors were related to interoceptive accuracy. This dissociation suggests disparate interoceptive mechanisms for the formation and/or maintenance of autistic features

Identifying with the beautiful: Facial attractiveness effects on unisensory and multisensory self-other distinction

People tend to evaluate their own traits and abilities favourably and such favourable self-perceptions extend to attractiveness. However, the exact mechanism underlying this self-enhancement bias remains unclear. One possibility could be the identification with attractive others through blurring of self–other boundaries. Across two experiments, we used the enfacement illusion to investigate the effect of others’ attractiveness in the multisensory perception of the self. In Experiment 1 (N = 35), participants received synchronous or asynchronous interpersonal visuo-tactile stimulation with an attractive and non-attractive face. In Experiment 2 (N = 35), two new faces were used and spatial incongruency was introduced as a control condition. The results showed that increased ratings of attractiveness of an unfamiliar face lead to blurring of self–other boundaries, allowing the identification of our psychological self with another’s physical self and specifically their face, and this seems to be unrelated to perceived own attractiveness. The effect of facial attractiveness on face ownership showed dissociable mechanisms, with multisensory integration modulating the effect on similarity but not identification, an effect that may be purely based on vision. Overall, our findings suggest that others’ attractiveness may lead to positive distortions of the self. This research provides a psychophysical starting point for studying the impact of others’ attractiveness on self-face recognition, which can be particularly important for individuals with malleable, embodied self–other boundaries and body image disturbances

Identifying with the Beautiful: Facial attractiveness effects on unisensory and multisensory self-other distinction

People tend to evaluate their own traits and abilities favourably and such favourable self-perceptions extend to attractiveness. However, the exact mechanism underlying this self-enhancement bias remains unclear and one possibility could be the identification with attractive others through blurring of self-other boundaries. Across two experiments, we used the enfacement illusion to investigate the effect of the attractiveness of others in the multisensory perception of the self. In a first experiment (N=35), participants were stroked on the cheek while looking at an attractive vs. non-attractive face being stroked on the cheek in synchrony or asynchrony. In the second experiment (N=35), two new faces were used and spatial incοngruency was introduced as a control condition. The results showed that increased ratings of attractiveness of an unfamiliar face lead to blurring of self-other boundaries, allowing the identification of our psychological self with another's physical self, and specifically their face, and this seems to be unrelated to perceived own attractiveness. The effect of facial attractiveness on face ownership showed dissociable mechanisms, with multisensory integration modulating the effect on similarity but not identification, an effect that may be purely based on vision. Overall, our findings suggest that others’ attractiveness may lead to positive distortions of the self, identifying with the more rather than less attractive others. This research provides a psychophysical starting point for studying the impact of others' attractiveness on how we perceive the self, which can be particularly important for individuals with malleable, embodied self-other boundaries and body image disturbances

Self–other distinction and borderline personality disorder features: Evidence for egocentric and altercentric bias in a self–other facial morphing task

Self–other distinction (SOD) refers to the ability to distinguish one’s own body, actions, and mental representations from those of others. Problems with SOD are considered to be a key feature of borderline personality disorder (BPD). However, empirical studies on SOD in BPD are scarce. Here, we present a study providing preliminary support for the usefulness and validity of a self–other facial morphing task to capture the capacity for SOD in a sample of nonclinical participants high (n = 30) and low (n = 32) in BPD features. Participants had to watch a video sequence in which their own face was gradually morphed into the face of an unfamiliar other (self-to-other) or vice versa (other-to-self), requiring them to indicate at which point they judged the morph to look more like the target face than the starting face. Consistent with predictions, results showed that participants in the high-BPD group judged the morph to look like themselves for longer in the self-to-other direction (suggestive of egocentric bias), but only with a relatively more attractive target face. In the other-to-self direction, the high-BPD group had more difficulty recognizing their own face (i.e., an altercentric bias), but this time only with the relatively less attractive face. Further research is needed to replicate these findings in clinical samples, but overall they suggest that the current task might be suited to investigate SOD problems in BPD. (PsycInfo Database Record (c) 2020 APA, all rights reserved

Comparing soft robotic affective touch to human and brush affective touch

Affective touch is important for maintaining emotional bonds and providing comfort. In this pilot study, we developed a silicone pneumatic soft robotic haptic device (S-CAT) to provide affective touch and compared its performance with commonly used brush and human affective touch. The S-CAT device simulates the attributes of CT-optimal affective touch in terms of velocity, temperature and force. In 22 participants we administered touch on their forearm from the S-CAT device (robot), a human hand and a soft brush at 6cm/s (CT-optimal speed) and 36cm/s (non-CT optimal speed). We collected subjective ratings on pleasantness and intensity, as well as electroencephalography (EEG) responses. The results showed that pleasantness and intensity ratings depend on velocity of the touch. Moreover, S-CAT touch delivered at these different velocities elicits similar subjective ratings to using a human hand or brush. Findings point to the potential for soft robotic haptic devices to modulate subjective and electrophysiological response in a similar way to more natural, human touch

Disconnections in personal neglect

Personal neglect is a disorder in the perception and representation of the body that causes the patients to behave as if the contralesional side of their body does not exist. This clinical condition has not been adequately investigated in the past as it has been considered a symptom of unilateral spatial neglect, which has mainly been studied with reference to extrapersonal space. Only a few studies with small samples have investigated the neuroanatomical correlates of personal neglect, and these have mainly focused on discrete cortical lesions and modular accounts, as well as being based on the hypothesis that this disorder is associated with somatosensory and spatial deficits. In the present study, we tested the novel hypothesis that personal neglect may be associated not only with discrete cortical and subcortical lesions, but also with disconnections of white matter tracts. We performed an advanced lesion analyses in a large sample of 104 right hemisphere damaged patients, 72 of whom were suffering from personal neglect. Results from the analyses of the grey and white matter were controlled for co-occurrent clinical variables such as extrapersonal neglect, anosognosia for hemiplegia and motor deficits, along with other lesion-related variables such as lesion size and the interval from the lesion onset to neuroimaging recordings. Our results reveal that personal neglect is associated with lesions in a medial network which involves the temporal cortex (Heschl's gyrus), the ventro-lateral nuclei of the thalamus and the fornix. This suggests that personal neglect involves a convergence between sensorimotor processes, spatial representation and the processing of self-referred information (episodic memory)

Disconnections in personal neglect

: Personal neglect is a disorder in the perception and representation of the body that causes the patients to behave as if the contralesional side of their body does not exist. This clinical condition has not been adequately investigated in the past as it has been considered a symptom of unilateral spatial neglect, which has mainly been studied with reference to extrapersonal space. Only a few studies with small samples have investigated the neuroanatomical correlates of personal neglect, and these have mainly focused on discrete cortical lesions and modular accounts, as well as being based on the hypothesis that this disorder is associated with somatosensory and spatial deficits. In the present study, we tested the novel hypothesis that personal neglect may be associated not only with discrete cortical and subcortical lesions, but also with disconnections of white matter tracts. We performed an advanced lesion analyses in a large sample of 104 right hemisphere damaged patients, 72 of whom were suffering from personal neglect. Results from the analyses of the grey and white matter were controlled for co-occurrent clinical variables such as extrapersonal neglect, anosognosia for hemiplegia and motor deficits, along with other lesion-related variables such as lesion size and the interval from the lesion onset to neuroimaging recordings. Our results reveal that personal neglect is associated with lesions in a medial network which involves the temporal cortex (Heschl's gyrus), the ventro-lateral nuclei of the thalamus and the fornix. This suggests that personal neglect involves a convergence between sensorimotor processes, spatial representation and the processing of self-referred information (episodic memory)