| 1. |
- Böhme, Rebecca, et al.
(författare)
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Distinction of self-produced touch and social touch at cortical and spinal cord levels
- 2019
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : NATL ACAD SCIENCES. - 0027-8424 .- 1091-6490. ; 116:6, s. 2290-2299
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Tidskriftsartikel (refereegranskat)abstract
- Differentiation between self-produced tactile stimuli and touch by others is necessary for social interactions and for a coherent concept of "self." The mechanisms underlying this distinction are unknown. Here, we investigated the distinction between self-and other-produced light touch in healthy volunteers using three different approaches: fMRI, behavioral testing, and somatosensory-evoked potentials (SEPs) at spinal and cortical levels. Using fMRI, we found self-other differentiation in somatosensory and sociocognitive areas. Other-touch was related to activation in several areas, including somatosensory cortex, insula, superior temporal gyrus, supramarginal gyrus, striatum, amygdala, cerebellum, and prefrontal cortex. During self-touch, we instead found deactivation in insula, anterior cingulate cortex, superior temporal gyrus, amygdala, parahippocampal gyrus, and prefrontal areas. Deactivation extended into brain areas encoding low-level sensory representations, including thalamus and brainstem. These findings were replicated in a second cohort. During self-touch, the sensorimotor cortex was functionally connected to the insula, and the threshold for detection of an additional tactile stimulus was elevated. Differential encoding of self-vs. other-touch during fMRI correlated with the individual self-concept strength. In SEP, cortical amplitudes were reduced during self-touch, while latencies at cortical and spinal levels were faster for other-touch. We thus demonstrated a robust self-other distinction in brain areas related to somatosensory, social cognitive, and interoceptive processing. Signs of this distinction were evident at the spinal cord. Our results provide a framework for future studies in autism, schizophrenia, and emotionally unstable personality disorder, conditions where symptoms include social touch avoidance and poor self-vs.-other discrimination.
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| 2. |
- Hauser, Steven C., et al.
(författare)
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From Human-to-Human Touch to Peripheral Nerve Responses
- 2019
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Ingår i: 2019 IEEE WORLD HAPTICS CONFERENCE (WHC). - : IEEE. - 9781538694619 - 9781538694626 ; , s. 592-597
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Konferensbidrag (refereegranskat)abstract
- Human-to-human touch conveys rich, meaningful social and emotional sentiment. At present, however, we understand neither the physical attributes that underlie such touch, nor how the attributes evoke responses in unique types of peripheral afferents. Indeed, nearly all electrophysiological studies use well-controlled but non-ecological stimuli. Here, we develop motion tracking and algorithms to quantify physical attributes indentation depth, shear velocity, contact area, and distance to the cutaneous sensory space (receptive field) of the afferent underlying human-to-human touch. In particular, 2-D video of the scene is combined with 3-D stereo infrared video of the touchers hand to measure contact interactions local to the receptive field of the receivers afferent. The combined and algorithmically corrected measurements improve accuracy, especially of occluded and misidentified fingers. Human subjects experiments track a toucher performing four gestures - single finger tapping, multi-finger tapping, multi-finger stroking and whole hand holding - while action potentials are recorded from a first-order afferent of the receiver. A case study with one rapidly-adapting (Pacinian) and one C-tactile afferent examines temporal ties between gestures and elicited action potentials. The results indicate this method holds promise in determining the roles of unique afferent types in encoding social and emotional touch attributes in their naturalistic delivery.
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| 3. |
- Hauser, Steven C., et al.
(författare)
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Uncovering Human-to-Human Physical Interactions that Underlie Emotional and Affective Touch Communication
- 2019
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Ingår i: 2019 IEEE WORLD HAPTICS CONFERENCE (WHC). - : IEEE. - 9781538694619 - 9781538694626 ; , s. 407-412
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Konferensbidrag (refereegranskat)abstract
- Couples often communicate their emotions, e.g., love or sadness, through physical expressions of touch. Prior efforts have used visual observation to distinguish emotional touch communications by certain gestures tied to ones hand contact, velocity and position. The work herein describes an automated approach to eliciting the essential features of these gestures. First, a tracking system records the timing and location of contact interactions in 3-D between a touchers hand and a receivers forearm. Second, data post-processing algorithms extract dependent measures, derived from prior visual observation, tied to the intensity and velocity of the touchers hand, as well as areas, durations and parts of the hand in contact. Third, behavioral data were obtained from five couples who sought to convey a variety of emotional word cues. We found that certain combinations of six dependent measures well distinguish the touch communications. For example, a typical sadness expression invokes more contact, evolves more slowly, and impresses less deeply into the forearm than a typical attention expression. Furthermore, cluster analysis indicates 2-5 distinct expression strategies are common per word being communicated. Specifying the essential features of touch communications can guide haptic devices in reproducing naturalistic interactions.
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| 4. |
- Mcintyre, Sarah, 1981-, et al.
(författare)
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The Language of Social Touch Is Intuitive and Quantifiable
- 2022
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Ingår i: Psychological Science. - : Sage Publications Inc. - 0956-7976 .- 1467-9280. ; 33:9, s. 1477-1494
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Tidskriftsartikel (refereegranskat)abstract
- Touch is a powerful communication tool, but we have a limited understanding of the role played by particular physical features of interpersonal touch communication. In this study, adults living in Sweden performed a task in which messages (attention, love, happiness, calming, sadness, and gratitude) were conveyed by a sender touching the forearm of a receiver, who interpreted the messages. Two experiments (N = 32, N = 20) showed that within close relationships, receivers could identify the intuitive touch expressions of the senders, and we characterized the physical features of the touches associated with successful communication. Facial expressions measured with electromyography varied by message but were uncorrelated with communication performance. We developed standardized touch expressions and quantified the physical features with 3D hand tracking. In two further experiments (N = 20, N = 16), these standardized expressions were conveyed by trained senders and were readily understood by strangers unacquainted with the senders. Thus, the possibility emerges of a standardized, intuitively understood language of social touch.
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| 5. |
- Rezaei, Merat, et al.
(författare)
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Thin Films on the Skin, but not Frictional Agents, Attenuate the Percept of Pleasantness to Brushed Stimuli
- 2021
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Ingår i: 2021 IEEE WORLD HAPTICS CONFERENCE (WHC). - : IEEE. - 9781665418713 ; , s. 49-54
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Konferensbidrag (refereegranskat)abstract
- Brushed stimuli are perceived as pleasant when stroked lightly on the skin surface of a touch receiver at certain velocities. While the relationship between brush velocity and pleasantness has been widely replicated, we do not understand how resultant skin movements - e.g., lateral stretch, stick-slip, normal indentation - drive us to form such judgments. In a series of psychophysical experiments, this work modulates skin movements by varying stimulus stiffness and employing various treatments. The stimuli include brushes of three levels of stiffness and an ungloved human finger. The skins friction is modulated via non-hazardous chemicals and washing protocols, and the skins thickness and lateral movement are modulated by thin sheets of adhesive film. The stimuli are hand-brushed at controlled forces and velocities. Human participants report perceived pleasantness per trial using ratio scaling. The results indicate that a brushs stiffness influenced pleasantness more than any skin treatment. Surprisingly, varying the skins friction did not affect pleasantness. However, the application of a thin elastic film modulated pleasantness. Such barriers, though elastic and only 40 microns thick, inhibit the skins tangential movement and disperse normal force. The finding that thin films modulate affective interactions has implications for wearable sensors and actuation devices.
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| 6. |
- Xu, Shan, et al.
(författare)
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3D Visual Tracking to Quantify Physical Contact Interactions in Human-to-Human Touch
- 2022
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Ingår i: Frontiers in Physiology. - : Frontiers Media SA. - 1664-042X. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Across a plethora of social situations, we touch others in natural and intuitive ways to share thoughts and emotions, such as tapping to get ones attention or caressing to soothe ones anxiety. A deeper understanding of these human-to-human interactions will require, in part, the precise measurement of skin-to-skin physical contact. Among prior efforts, each measurement approach exhibits certain constraints, e.g., motion trackers do not capture the precise shape of skin surfaces, while pressure sensors impede skin-to-skin contact. In contrast, this work develops an interference-free 3D visual tracking system using a depth camera to measure the contact attributes between the bare hand of a toucher and the forearm of a receiver. The touchers hand is tracked as a posed and positioned mesh by fitting a hand model to detected 3D hand joints, whereas a receivers forearm is extracted as a 3D surface updated upon repeated skin contact. Based on a contact model involving point clouds, the spatiotemporal changes of hand-to-forearm contact are decomposed as six, high-resolution, time-series contact attributes, i.e., contact area, indentation depth, absolute velocity, and three orthogonal velocity components, together with contact duration. To examine the systems capabilities and limitations, two types of experiments were performed. First, to evaluate its ability to discern human touches, one person delivered cued social messages, e.g., happiness, anger, sympathy, to another person using their preferred gestures. The results indicated that messages and gestures, as well as the identities of the touchers, were readily discerned from their contact attributes. Second, the systems spatiotemporal accuracy was validated against measurements from independent devices, including an electromagnetic motion tracker, sensorized pressure mat, and laser displacement sensor. While validated here in the context of social communication, this system is extendable to human touch interactions such as maternal care of infants and massage therapy.
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| 7. |
- Xu, Shan, et al.
(författare)
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Subtle Contact Nuances in the Delivery of Human-to-Human Touch Distinguish Emotional Sentiment
- 2022
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Ingår i: IEEE Transactions on Haptics. - : IEEE COMPUTER SOC. - 1939-1412 .- 2329-4051. ; 15:1, s. 97-102
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Tidskriftsartikel (refereegranskat)abstract
- We routinely communicate distinct social and emotional sentiments through nuanced touch. For example, we might gently hold anothers arm to offer a sense of calm, yet intensively hold anothers arm to express excitement or anxiety. As this example indicates, distinct sentiments may be shaped by the subtlety in ones touch delivery. This work investigates how slight distinctions in skin-to-skin contact influence both the recognition of cued emotional messages (e.g., anger, sympathy) and the rating of emotional content (i.e., arousal, valence). By self-selecting preferred gestures (e.g., holding, stroking), touchers convey distinct messages by touching the receivers forearm. Skin-to-skin contact attributes (e.g., velocity, depth, area) are optically tracked in high resolution. Contact is then examined within gesture, between messages. The results indicate touchers subtly, but significantly, vary contact attributes of a gesture to communicate distinct messages, which are recognizable by receivers. This tuning also correlates with receivers arousal and valence. For instance, arousal increases with velocity for stroking, and depth for holding. Moreover, as shown here with human-to-human touch, valence is tied with velocity, which is the same trend as reported with brushes. The findings indicate that subtle nuance in skin-to-skin contact is important in conveying social messages and inducing emotions.
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