Touch Conditions Research Articles

Effect of touch on proprioception: non-invasive trigeminal nerve stimulation suggests general arousal rather than tactile-proprioceptive integration.

Proprioceptive error of estimated fingertip position in two-dimensional space is reduced with the addition of tactile stimulation applied at the fingertip. Tactile input does not disrupt the participants' estimation strategy, as the individual error vector maps maintain their overall structure. This relationship suggests integration of proprioception and tactile information improves proprioceptive estimation, which can also be improved with trained mental focus and attention. Task attention and arousal are physiologically regulated by the reticular activating system (RAS), a brainstem circuit including the locus coeruleus (LC). There is direct and indirect evidence that these structures can be modulated by non-invasive trigeminal nerve stimulation (nTNS), providing an opportunity to examine nTNS effect on the integrative relationship of proprioceptive and tactile information. Fifteen right-handed participants performed a simple right-handed proprioceptive estimation task with tactile feedback (touch) and no tactile (hover) feedback. Participants repeated the task after nTNS administration. Stimulation was delivered for 10 min, and stimulation parameters were 3,000 Hz, 50 μs pulse width, with a mean of 7 mA. Error maps across the workspace are generated using polynomial models of the participants' target responses. Error maps did not demonstrate significant vector direction changes between conditions for any participant, indicating that nTNS does not disrupt spatial proprioception estimation strategies. A linear mixed model regression with nTNS epoch, tactile condition, and the interaction as factors demonstrated that nTNS reduced proprioceptive error under the hover condition only. We argue that nTNS does not disrupt spatial proprioceptive error maps but can improve proprioceptive estimation in the absence of tactile feedback. However, we observe no evidence that nTNS enhances tactile-proprioceptive integration as the touch condition does not exhibit significantly reduced error after nTNS.

Fingertip light touch contact increases anteroposterior limits of stability in healthy young and older adults

BackgroundThe limit of stability (LoS), an index of stance balance ability, is reduced in older adults. Although contacting an earth-fixed external surface through fingertips’ light touch improves older adults’ stance balance control, its effects on the LoS in this population are unclear. Research questionDoes light touch increase the LoS and reduce postural sway in the LoS? MethodsThis study included 20 young adults (11 women and 9 men, mean age = 20.6 years) and 15 community-dwelling older adults (8 women and 7 men, mean age = 74.5 years). The position and path length of the center of pressure (CoP) during quiet standing (QS) and the anterior and posterior LoS (A-LoS and P-LoS, respectively) were measured using a force platform under two touch conditions (no-touch condition and light-touch condition). In light-touch condition, participants placed the tip of their dominant index finger on a load cell, which had an applied force of <1 N. ResultsIn both touch conditions, the older group had a more limited CoP position in the anteroposterior LoS and a longer CoP path length in the QS and LoS than the younger group. In both participant groups, the light-touch condition showed a wider CoP position in the anteroposterior LoS and a shorter CoP path length in the QS and LoS than the no-touch condition. SignificanceLight touch increases the anteroposterior LoS and decreases postural sway in the LoS. Therefore, contacting an external object by fingertips’ light touch may be an effective training protocol to increase the LoS in older adults.

Semi-autonomous touch method merging robot’s autonomous touch and user-operated touch for improving user experience in robot touch

The demand for therapeutic robots to alleviate mental health problems is growing. Studies have shown that people’s mental health improves when they are touched. Consequently, therapeutic robots are designed to alleviate stress through robot’s autonomous touch. However, robot’s autonomous touch can sometimes cause discomfort to recipients. This paper proposes a semi-autonomous touch method that merges robot’s autonomous touch with user-operated touch to mitigate discomfort while maintaining the sensation of being touched by another person. We conducted an experiment involving 24 participants who were touched on the neck by robots under three conditions: robot’s autonomous touch, user-operated touch, and the proposed semi-autonomous touch method condition. Additionally, the study investigated participants’ impressions of the robot in each condition. The results showed that semi-autonomous touch condition mitigated discomfort more effectively compared with the robot’s autonomous touch method condition. It also enhanced the feeling of being touched by another person entity and suppressed interaction boredom compared with the user-operated touch method condition. Participants reported higher trustworthiness and perceived friendliness in robots utilizing the semi-autonomous touch method compared to those with autonomous touch method condition. These findings indicate that robots featuring the proposed semi-autonomous touch method can provide a comforting experience, leveraging the therapeutic benefits of being touched by another person, and underscore their potential in mental health applications.

Effect of gentle human touch and oral sucrose on distress relief in preterm neonates: A randomized crossover controlled trial

PurposeThis study was conducted with the aim of comparing gentle human touch and oral sucrose on the distress caused by the placement of a oral-gastric tube in preterm infants admitted to the NICU. MethodsThis prospective randomized crossover controlled trial was performed between June to December 2023 in Tehran, Iran. ResultsThe results showed that, at the baseline, there was not statistically significant difference between the mean distress score of participations in the control condition, gentle human touch condition and the sucrose condition (P = 0.139) but after the intervention, the mean distress score in the gentle human touch was significantly lower than the control and sucrose conditions (P < 0.001) and there was not statistically significant difference between the control and sucrose conditions (P = 0.651). ConclusionThe findings of this study showed that gentle human touch is more effective and more sustained than oral sucrose in reducing the distress of preterm infants. Trial registrationThis study is registered in Iranian Registry of Clinical Trials (https://en.irct.ir/) with IRCTID: 20230202057303N1 on 2023-04-06.

The effects of types of touch and haptic cues on choice overload

AbstractAlthough consumers are commonly exposed to numerous choices and the opportunity to touch products when they shop, the literature remains unclear on how both factors simultaneously affect choice. With the growth of online shopping, touch literature has studied the effects of mere touch (i.e., nondiagnostic tactile contact) or vicarious touch (e.g., observing a hand in physical contact with a product or imagining touching a product) to demonstrate that these nondiagnostic haptic inputs can comparably influence consumer attitude, just like diagnostic touch. By investigating the moderating effects of different haptic inputs on choice overload, this research reveals certain conditions in which nondiagnostic haptic inputs operate differently than those of diagnostic touch. We find that both mere touch (Study 1) and vicarious touch (Study 2) help reduce choice overload effects by eliminating the effect of choice set size on choice uncertainty, which is typically observed in the no touch (i.e., control) condition. As haptic cues have been increasingly employed to aid the online shopping experience for consumers, we also find that the choice overload effect is eliminated when an autotelic haptic cue is presented but amplified when an instrumental haptic cue is provided (Study 3). Besides, this research demonstrates that, while the moderating effects of the nondiagnostic haptic inputs are driven by increased personal control, instrumental touch can amplify choice overload effects due to the increased choice difficulty when choosing from large (vs. small) choice sets. These findings help retailers know what type of haptic cues to apply or avoid, as consumers have already been overloaded with abundant choices when they shop online.

Potential mental health-related harms associated with the universal screening of anxiety and depressive symptoms in Australian secondary schools

BackgroundAnxiety and depressive disorders typically emerge in adolescence and can be chronic and disabling if not identified and treated early. School-based universal mental health screening may identify young people in need of mental health support and facilitate access to treatment. However, few studies have assessed the potential harms of this approach. This paper examines some of the potential mental health-related harms associated with the universal screening of anxiety and depression administered in Australian secondary schools.MethodsA total of 1802 adolescent students from 22 secondary schools in New South Wales, Australia, were cluster randomised (at the school level) to receive either an intensive screening procedure (intervention) or a light touch screening procedure (control). Participants in the intensive screening condition received supervised self-report web-based screening questionnaires for anxiety, depression and suicidality with the follow-up care matched to their symptom severity. Participants in the light touch condition received unsupervised web-based screening for anxiety and depression only, followed by generalised advice on help-seeking. No other care was provided in this condition. Study outcomes included the increased risk of anxiety, depression, psychological distress, decreased risk of help-seeking, increased risk of mental health stigma, determined from measures assessed at baseline, 6 weeks post-baseline, and 12 weeks post-baseline. Differences between groups were analysed using mixed effect models.ResultsParticipants in the intensive screening group were not adversely affected when compared to the light touch screening condition across a range of potential harms. Rather, participants in the intensive screening group were found to have a decreased risk of inhibited help-seeking behaviour compared to the light touch screening condition.ConclusionsThe intensive screening procedure did not appear to adversely impact adolescents’ mental health relative to the light touch procedure. Future studies should examine other school-based approaches that may be more effective and efficient than universal screening for reducing mental health burden among students.Trial registration Australian and New Zealand Clinical Trials Registry (ACTRN12618001539224) https://anzctr.org.au/Trial/Registration/TrialReview.aspx?id=375821.

In your skin? Somatosensory cortex is purposely recruited to situate but not simulate vicarious touch

Previous studies of vicarious touch suggest that we automatically simulate observed touch experiences in our own body representation including primary and secondary somatosensory cortex (SCx). However, whether these early sensory areas are activated in a reflexive manner and the extent with which such SCx activations represent touch qualities, like texture, remains unclear. We measured event-related potentials (ERPs) of SCx's hierarchical processing stages, which map onto successive somatosensory ERP components, to investigate the timing of vicarious touch effects. In the first experiment, participants (n = 43) merely observed touch or no-touch to a hand; in the second, participants saw different touch textures (soft foam and hard rubber) either touching a hand (other-directed) or they were instructed that the touch was self-directed and to feel the touch. Each touch sequence was followed by a go/no-go task. We probed SCx activity and isolated SCx vicarious touch activations from visual carry over effects. We found that vicarious touch conditions (touch versus no-touch and soft versus hard) did not modulate early sensory ERP components (i.e. P50, N80); but we found effects on behavioural responses to the subsequent go/no-go stimulus consistent with post-perceptual effects. When comparing other- with self-directed touch conditions, we found that early and mid-latency components (i.e. P50, N80, P100, N140) were modulated consistent with early SCx activations. Importantly, these early sensory activations were not modulated by touch texture. Therefore, SCx is purposely recruited when participants are instructed to attend to touch; but such activation only situates, rather than fully simulates, the seen tactile experience in SCx.

Stationary Haptic Stimuli Do not Produce Ocular Accommodation in Most Individuals.

This study aimed to determine the extent to which haptic stimuli can influence ocular accommodation, either alone or in combination with vision. Accommodation was measured objectively in 15 young adults as they read stationary targets containing Braille letters. These cards were presented at four distances in the range 20-50cm. In the Touch condition, the participant read by touch with their dominant hand in a dark room. Afterward, they estimated card distance with their non-dominant hand. In the Vision condition, they read by sight binocularly without touch in a lighted room. In the Touch with Vision condition, they read by sight binocularly and with touch in a lighted room. Sensory modality had a significant overall effect on the slope of the accommodative stimulus-response function. The slope in the Touch condition was not significantly different from zero, even though depth perception from touch was accurate. Nevertheless, one atypical participant had a moderate accommodative slope in the Touch condition. The accommodative slope in the Touch condition was significantly poorer than in the Vision condition. The accommodative slopes in the Vision condition and Touch with Vision condition were not significantly different. For most individuals, haptic stimuli for stationary objects do not influence the accommodation response, alone or in combination with vision. These haptic stimuli provide accurate distance perception, thus questioning the general validity of Heath's model of proximal accommodation as driven by perceived distance. Instead, proximally induced accommodation relies on visual rather than touch stimuli.

Movement-related tactile gating in blindness

When we perform an action, self-elicited movement induces suppression of somatosensory information to the cortex, requiring a correct motor-sensory and inter-sensory (i.e. cutaneous senses, kinesthesia, and proprioception) integration processes to be successful. However, recent works show that blindness might impact some of these elements. The current study investigates the effect of movement on tactile perception and the role of vision in this process. We measured the velocity discrimination threshold in 18 sighted and 18 blind individuals by having them perceive a sequence of two movements and discriminate the faster one in passive and active touch conditions. Participants’ Just Noticeable Difference (JND) was measured to quantify their precision. Results showed a generally worse performance during the active touch condition compared to the passive. In particular, this difference was significant in the blind group, regardless of the blindness duration, but not in the sighted one. These findings suggest that the absence of visual calibration impacts motor-sensory and inter-sensory integration required during movement, diminishing the reliability of tactile signals in blind individuals. Our work spotlights the need for intervention in this population and should be considered in the sensory substitution/reinforcement device design.

How to make vertical farming more attractive: Effects of vegetable growing conditions on consumer assessment

AbstractVertical farming is emerging as a new agricultural technology. Following this trend, we compare vertical farming with conventional farming and derive various results by examining consumer perceptions. Specifically, Study 1 investigates the difference between product evaluation and purchase intention according to growing conditions and suggests an underlying mechanism in the relationship between the two. Consequently, consumers prefer crops grown on conventional farms over those grown on vertical farms. This is because consumers perceive higher naturalness and healthfulness in conventional farming methods. Studies 2 and 3 suggest human touch to evaluate vertical farming more favorably. In these experiments, we consider whether similar results could be obtained by presenting different conditions under which the human touch was utilized. According to the results of examining the moderating effect of human touch, consumers positively evaluate high human touch conditions, even for vegetables grown on vertical farms.

Tactile and visual perception of plastic textures for car interiors: Psychophysical and affective dimensions

Surface textures play an important role in the perception of consumer products. In car interiors, they are a major contributor to the perceived quality of a vehicle. However, limited attention has been paid to the affective responses elicited by touch and observation of a textured surface. Here we report an investigation in which Kansei Engineering was used to explore the perception of texturized plastic surfaces, both in its psychophysical and affective dimensions, as well as the influence of the textures’ physical parameters. In a controlled study, 21 subjects were asked to touch 18 samples of two types of plastics, commonly used in car interiors, Polypropylene (PP) and Acrylonitrile Butadiene Styrene (ABS), under tactile (only touch) and visual-tactile (touch and vision) conditions. Participants were asked to rate the samples according to 8 descriptors of psychophysical and affective nature. Results show a relation between perceived roughness and the positive/negative valence of the affective response. Importantly, this relation is moderated by the visual appearance of the textures, when these are visible. Both psychophysical and affective dimensions were modelled through height parameters of the texture elements and a variable describing the type of material. The present findings are relevant for the understanding of visual-tactile perception of textures and have implications in the design of textured components for automotive car interiors.

Young Individuals Are More Stable and Stand More Upright When Using Rollator Assistance During Standing up and Sitting Down.

Four-wheeled walkers or rollators are often used to assist older individuals in maintaining an independent life by compensating for muscle weakness and reduced movement stability. However, limited biomechanical studies have been performed to understand how rollator support affects posture and stability, especially when standing up and sitting down. Therefore, this study examined how stability and posture change with varying levels of rollator support and on an unstable floor. The aim was to collect comprehensive baseline data during standing up and sitting down in young participants. In this study, 20 able-bodied, young participants stood up and sat down both 1) unassisted and assisted using a custom-made robot rollator simulator under 2) full support and 3) touch support. Unassisted and assisted performances were analyzed on normal and unstable floors using balance pads with a compliant surface under each foot. Using 3D motion capturing and two ground-embedded force plates, we compared assistive support and floor conditions for movement duration, the relative timing of seat-off, movement stability (center of pressure (COP) path length and sway area), and posture after standing up (lower body sagittal joint angles) using ANOVA analysis. The relative event of seat-off was earliest under full support compared to touch and unassisted conditions under normal but not under unstable floor conditions. The duration of standing up and sitting down did not differ between support conditions on normal or unstable floors. COP path length and sway area during both standing up and sitting down were lowest under full support regardless of both floor conditions. Hip and knee joints were least flexed under full support, with no differences between touch and unassisted in both floor conditions. Hence, full rollator support led to increased movement stability, while not slowing down the movement, during both standing up and sitting down. During standing up, the full support led to an earlier seat-off and a more upright standing posture when reaching a stable stance. These results indicate that rollator support when handles are correctly aligned does not lead to the detrimental movement alterations of increased forward-leaning. Future research aims to verify these findings in older persons with stability and muscle weakness deficiencies.

Testing links between pain-related biases in visual attention and recognition memory: An eye-tracking study based on an impending pain paradigm.

Although separate lines of research have evaluated pain-related biases in attention or memory, laboratory studies examining links between attention and memory for pain-related information have received little consideration. In this eye-tracking experiment, we assessed relations between pain-related attention biases (ABs) and recognition memory biases (MBs) among 122 pain-free adults randomly assigned to impending pain (n = 59) versus impending touch (n = 63) conditions, wherein offsets of trials that included pain images were followed by subsequent possibly painful and non-painful somatosensory stimulation, respectively. Gaze biases of participants were assessed during presentations of pain-neutral (P-N) and happy-neutral (H-N) face image pairs within these conditions. Subsequently, condition differences in recognition accuracy for previously viewed versus novel pained and happy face images were examined. Overall gaze durations were significantly longer for pain (vs. neutral) faces that signalled impending pain than impending non-painful touch, particularly among the less resilient in the former condition. Impending pain cohorts also exhibited comparatively better recognition accuracy for both pained and happy face images. Finally, longer gaze durations on pain faces that signalled potential pain, but not potential touch, were related to more accurate recognition of previously viewed pain faces. In sum, pain cues that signal potential personal discomfort maintain visual attention more fully and are subsequently recognised more accuracy than are pain cues that signal non-painful touch stimulation.

An Open-Environment Tactile Sensing System: Toward Simple and Efficient Material Identification.

Robotic perception can have simple and effective sensing functions that are unreachable for humans using only the isolated tactile perception method, with the assistance of a triboelectric nanogenerator (TENG). However, the reliability of triboelectric sensors remains a major challenge due to the inherent environmental limitations. Here, an intelligent tactile sensing system that combines a TENG and deep-learning technology is proposed. Using a triboelectric triple tactile sensor array, typical characteristics of each testing material can be maintained stably even under different contact conditions (touch conditions and external environmental conditions) by extracting features from three independent electrical signals as well as the normalized output signals. Furthermore, a convolutional neural network model is integrated, and a high accuracy of 96.62% is achieved in a material identification task. The tactile sensing system is exhibited to an open environment for material identification and the real-time demonstration. Compared to the complex process that humans must integrate multiple sensing (touching and viewing) to accomplish tactile perception, the proposed sensing system shows a huge advantage in cognitive learning for the visually impaired, biomimetic prosthetics, and virtual spaces construction.

Effects of light finger touch on the regularity of center-of-pressure fluctuations during quiet bipedal and single-leg postural tasks

BackgroundThe use of extra sources of sensory information associated with light fingertip touch to enhance postural steadiness has been associated with increased attentional demands, whereas the regularity of center of pressure (COP) fluctuations has been interpreted as a marker of the amount of attention invested in posture control. Research questionThis study addressed whether increased attentional demands associated with postural tasks involving light finger touch might be reflected by measures of COP regularity. MethodsThe experiments involved quiet bipedal stance (n = 8 participants) and single-legged stance (n = 14 participants). Each participant was instructed to stand as quietly as possible on a force plate, either touching an external rigid surface (applied force < 1 N, light touch condition), or not (no touch condition). Postural steadiness was assessed by traditional COP measurements (COP Area, RMS, and velocity), whereas the regularity of postural sway was based on estimates of the sample entropy (SaEn) of the COP time series. ResultsTraditional parameters of postural sway and COP regularity (inversely related to SaEn COP measurements) were reduced during the touch conditions as compared to the no-touch conditions, for both bipedal quiet stance and single-legged stance. Decreased COP regularity with light touch was mainly reflected in the direction of the largest postural sway (i.e. in the sagittal plane for bipedal stance and in the frontal plane for single-legged stance). SignificanceThe present results suggest that actively touching an external surface with the fingertip, besides increasing postural steadiness, generated an externally oriented (presumably cognitive-dependent) focus of attention, so that participants invested less attention on the postural task per se (as suggested by increased SaEn), which might be associated with a more “automatic” control of posture.

Interactions between rearward-facing child restraint systems and the front row seatback in frontal impact sled tests

Objective Some child restraint system (CRS) manufacturers specify a minimum distance between the CRS and the seatback, whereas others require that the CRS may contact the seatback but cannot be “braced”; however, few studies have investigated these interactions. Therefore, the aim was to investigate the interactions between the front row seat and rearward-facing CRS models with and without a support leg during frontal crashes. Methods Sled tests using the FMVSS 213 frontal crash pulse were performed with the Q1.5 and Q3 anthropomorphic test devices (ATDs) seated in rearward-facing infant and convertible CRS models, respectively. A front row vehicle seat was in front of the test bench in three track positions: brace, touch and gap. For the touch condition, the front row seat was translated aftward until the seatback contacted the CRS. For the brace condition, the front row seat was translated 20 mm aftward. For the gap condition, the front row seat was translated 50 mm forward. Each condition was tested with and without the support leg of the CRS. Results The tests with a support leg were associated with significantly (p = 0.007) lower resultant linear head acceleration 3 ms clip compared to the tests without a support leg, but the reduction of head injury criterion 15 ms (HIC15) was not significant (p = 0.057). The Q1.5 ATD in the rearward-facing infant CRS with a support leg had the lowest injury metrics for the touch and gap conditions, whereas the Q3 in the rearward-facing convertible CRS had the lowest head injury metrics for the brace condition. Conclusions The use of a support leg provided a clear benefit in terms of reducing head injury metrics for the Q1.5 in the rearward-facing infant CRS, especially for the touch and gap conditions. The rearward-facing convertible CRS in the current study appears to benefit from being braced against the front row seat. However, further tests are required to allow further statistical comparisons and determine if these preliminary findings extend to other rearward-facing CRS models.

The effect of visual and tactile information in motor preparation of climbing

ABSTRACT In rock climbing, an appropriate motor preparation to a given climbing hold(s) is crucial for a fluent climbing. We investigated the influence of visual-tactile information in motor preparation of climbing, particularly the effect of the number of the holds and the tactile input of an actual hold was examined. Reaction times (RTs) under the priming paradigm were compared for climbers and non-climbers. Participants were asked to respond to a visual target (left or right arrow) after the presentation of a picture of a single climbing hold (Single-Prime condition: SP) or two holds (Double-Prime condition: DP). Before commencing each trial block, the participants were also asked to touch or watch an actual hold (touch /no-touch condition). The response based on the congruity between the orientation of the hold and that of the arrow was categorised as either congruent or incongruent. An ANOVA performed on the RTs showed the congruency effect, but this was observed only in the non-climbers. An additional analysis revealed a marginally significant climbing experience-related interaction. In the high-experienced climbers, the RTs in the touch condition were slower than those in the no-touch condition but this was only in the SP condition. In the no-touch condition, the RTs of DP were slower than those of SP. These results therefore suggest that the motor preparation is mediated by visual and tactile inputs of a given hold. The time needed for motor preparation, particularly in highly experienced climbers, may be modulated by the representational complexity of climbing movements through tactile information. Highlight The number of the holds visually presented affected the motor preparation. The tactile input of the climbing hold modulated the motor preparation only in the highly experienced climbers. Our findings imply that climbing-specific context (i.e. combination of the given holds) and experience (i.e. action competency) are involved in the motor preparation of climbing.

The effect of a light finger touch on the signal complexity during quiet standing

Purpose The purpose of the study was to investigate the influence of additional tactile information (light fingertip touch) on the postural sway and regularity of center-of-pressure (COP) fluctuations. Methods Thirty-two young, healthy participants performed a quiet standing task (30s) on a force platform with and without light touch. COP time-series were analyzed using standard postural sway measures (range, root mean square error, velocity), COP regularity was measured with Sample entropy. Results Participants demonstrated significantly smaller postural sway with a light touch, but only in the anteroposterior direction. The amount of sway with additional tactile information in the sagittal plane reached the level of sway in the frontal plane without this information. Similarly, COP fluctuations were more irregular during light touch condition only in the anteroposterior direction, as evidenced by significantly higher Sample entropy. Furthermore, COP regularity decreased in the sagittal plane and reached level in the frontal plane without light touch. Conclusions These results suggest that postural sway is mostly controlled in the sagittal plane and that in the mediolateral direction the control is mostly automated. In conclusion, our results support the notion that the light touch provides additional information which enhances postural stabilization. Our results expand the relation between COP regularity and the attention invested in posture in the touch domain and prove that light touch, as an attentional demanding task, leads to increased COP irregularity. Nonlinear measures of signal regularity (i.e. SampEn) provide surplus insight into human postural control and can be used as an useful tool to traditional balance measures.

Force Control on Fingertip Using EMS to Maintain Light Touch.

Light touch on a rigid surface with minimal force below a specific threshold reduces postural sway by providing additional sensory cues from the fingertips. The feasibility of maintaining light touch depends on subject characteristics and task difficulty. Therefore, we introduce a method of maintaining light touch by using electrical muscle stimulation (EMS). We applied it in a single-leg standing task involving healthy adult subjects. The subjects stood upright in a single-leg stance on a firm surface and on foam rubber (FR), respectively, under three conditions: no touch (NT, NT-FR), light touch without EMS (LT, LT-FR), and light touch in which EMS was applied based on the contact force (LT-EMS, LT-EMS-FR). The results showed that the force control by EMS helped maintain light touch and reduce postural sway compared with the no-touch condition. The amplitude of postural sway under the touch condition with EMS was equivalent to that under the touch condition without EMS.

Self-soothing touch and being hugged reduce cortisol responses to stress: A randomized controlled trial on stress, physical touch, and social identity

BackgroundBeing touched by others improves stress coping. However, when touch from others is unavailable, feels uncomfortable, or is not considered to be safe (as in the COVID-19 pandemic), self-touch gestures, like placing a hand on the heart, may provide an alternative way to experience less strain. Methods and materialsIn this study, 159 healthy participants (96 women, 62 men, and 1 non-binary person), aged 18–35 years, were exposed to a standardized psychosocial stressor (Trier Social Stress Test) to investigate whether self-soothing touch or receiving a hug from others has a buffering effect on their stress responses. In addition, the study explored whether the effectiveness of these interventions is moderated by participants' assignment to a “personal” or “social” identity condition. Participants provided salivary cortisol samples, wore an ECG to record their heart rate, and completed self-report measures on stress-related subjective-emotional states during the study. ResultsFor cortisol, mixed-effects regression models with Touch and Identity as between-subject factors and Time as the within-subject factor yielded a significant main effect for touch and a significant interaction of Touch x Time indicating that cortisol levels differed between the experimental touch interventions. Post-hoc contrast tests showed that participants in both touch conditions had lower cortisol levels after the stressor than those in the control conditions. Heart rates and self-reported measures of stress neither differed across touch nor identity conditions. The three-way interaction for Touch x Identity x Time was non-significant for either outcome measure. DiscussionThese results are in line with previous work indicating that physical touch has protective effects on physiological stress responses but not necessarily on self-reported stress and suggest that self-soothing touch and receiving hugs are simple and yet potentially powerful means for buffering individuals' resilience against stress.