Touch Conditions Research Articles

P121 The neurophysiological underpinnings of mirror-touch synaesthesia: A TMS-EEG study

Introduction Mirror-touch synaesthesia (MTS) is the condition in which the view of a touch delivered to another person’s body (but not to objects) elicits subjective conscious tactile sensations on own body. At a neurophysiological level, MTS has been associated to an unusual hyper-activation of the tactile mirror system (Blakemore et al., 2005; Ward and Banissy, 2015). Recent studies showed that increasing the excitability of primary somatosensory cortex (S1), by mean of non-invasive brain stimulation techniques, induces MTS-like responses even in non-synesthetes in a vision-touch spatial congruity task (Bolognini et al., 2013, 2014). However, it is not clear yet whether synaesthesia-like sensations were induced through direct modulation of S1, or by modulating the functional interplay between SI and other connected brain regions. Objectives This study aims at clarifying this issue by exploring changes in S1 cortical excitability and connectivity by means of TMS-EEG technique. Materials and methods 10 healthy volunteers participated to the study. 4 TMS-EEG recordings were performed; in each 180 TMS single pulses were delivered to right S1 while participants were exposed, in a random order, to three conditions: (i) experiencing a real touch on the left hand (touch), the view of video-clips depicting either (ii) a touch to another person’ hand (mirror-touch) or (iii) a touch to a leaf (control stimulus). Concomitant EEG was recorded by a 60 channels cap. TMS pulses were delivered at two SOAs: 50 ms or 150 ms from stimulus onset. Results In the touch condition, TMS at 50 ms elicited greater TEPs than at 150 ms. Conversely, in the mirror-touch condition, TEPs increased at 150 ms as compared to 50 ms SOA. No difference across SOAs were present instead for TEPs in the control condition. Comparing the three conditions, the greatest mean TEPs on right S1 occurred in the touch condition, followed by the mirror-touch, both eliciting greater TEP than the control condition. Conclusions Preliminary results suggest a rise of S1 cortical excitability at 50 ms SOA in the touch condition, i.e. when the tactile stimulus processing is taking place, and, crucially, at 150 ms SOA in the mirror-touch condition. Download : Download high-res image (185KB) Download : Download full-size image Download : Download high-res image (128KB) Download : Download full-size image

Physiological Responses to Affective Tele-Touch during Induced Emotional Stimuli

The human touch has long been recognized to promote physical, emotional, social, and spiritual comfort. There are situations, however, when touch cannot be exchanged. Although mobile phones and web-based communication are ubiquitous, touch-a communication modality that conveys powerful messages-is inexistent in modern communications media. This paper describes a tele-touch device that transfers affective touch to another person through the internet. Commands for vibration, warmth, and tickle were sent over the internet to a haptic device at the subjects' forearm. With a heart rate (HR) monitor and a galvanic skin response (GSR) sensor, the physiological effect of the tele-touch device was evaluated as the subjects watched an emotionally-laden movie. We compared these to one group of subjects who were touched by their spouse or girlfriend and to subjects of a control group where no touch was provided. Results show that the HR of the subjects with the tele-touch device was not significantly different from those subjects who were touched by their loved ones. These results were in contrast to the subjects who were not provided with any form of touch. On the other hand, the GSR results revealed that all the three touch conditions were different from one another.

Good vibrations: Global processing can increase the pleasantness of touch.

Visual-tactile carry-over effects of global/local processing (attention to the whole, versus the details) have been reported under active touch conditions. We investigated whether carry-over effects of global/local processing also occur for passive touch and whether global/local processing has differential effects on affective and discriminative aspects of touch. Participants completed two tactile tasks involving pleasantness rating and discrimination of a set of tactile vibrations before and after completing a version of the Navon task that encouraged a focus on the global (n = 30), local (n = 30), or both (n = 30) features of a series of visual stimuli. In line with previous research suggesting a link between global processing and positive emotion, global processing increased pleasantness ratings of high-frequency (but not low-frequency) tactile vibrations. Local processing did not improve the ability to discriminate between vibrations of different frequencies, however. There was some evidence of a tactile-visual carry-over effect; prior local processing of tactile vibrations reduced global precedence during the Navon task in the control group. We have shown carry-over effects of global versus local processing on passive touch perception. These findings provide further evidence suggesting that a common perceptual mechanism determines processing level across modalities and show for the first time that prior global processing affects the pleasantness of touch.

Beyond the Bedroom: Cognitive, Affective, and Behavioral Responses to Partner Touch in Women With and Without Sexual Problems

Women with female sexual problems (FSP) are more likely than unaffected women to demonstrate negative appraisals, negative affect, and avoidance of sexual activity. Research suggests affected women also experience negative affect and avoidance in response to intimate partner contact for fear it will lead to sex. This online study examined whether women with FSP (N = 157) and without FSP (N = 129) exhibited different perceptions, affective reactions, and behavioral responses to hypothetical touch occurring outside sexual activity. Women (Mage = 30.70; SD = 6.66) were randomly assigned to one of three conditions representing hypothetical interactions with their partner (affectionate, sexual, or no touch), and answered questions about their perceptions of their partner’s sexual intentions and their own anticipated negative affect and behavioral avoidance. Women with FSP reported higher perceptions of sexual intent, negative affect, and avoidance in the sexual touch condition, and higher negative affect in the affectionate touch condition, than women without FSP. Results highlight that women with FSP have more negative reactions to partners’ hypothetical affectionate and sexual touch than women without FSP. Interventions for FSP may benefit from targeting women’s perceptions, affective reactions, and behavioral reactions to partner touch when it occurs outside of explicitly sexual contexts.

Empathy Predicts an Experimental Pain Reduction During Touch.

Previous studies have provided evidence for pain-alleviating effects of segmental tactile stimulation, yet the effect of social touch and its underlying mechanism is still unexplored. Considering that the soma affects the way we think, feel, and interact with others, it has been proposed that touch may communicate emotions, including empathy, interacting with the identity of the toucher. Thus, the goal of the current study was to examine the analgesic effects of social touch, and to test the moderating role of the toucher's empathy in analgesia using an ecological paradigm. Tonic heat stimuli were administered to women. Concurrently, their partners either watched or touched their hands, a stranger touched their hands, or no one interacted with them. The results revealed diminished levels of pain during partners' touch compared with all other control conditions. Furthermore, taking into account the dyadic interaction, only during the touch condition we found 1) a significant relationship between the partners' pain ratings, and 2) a significant negative relationship between the male touchers' empathy and the pain experience of their female partners. The findings highlight the powerful analgesic effect of social touch and suggest that empathy between romantic partners may explain the pain-alleviating effects of social touch. Pain research mostly concentrates on different factors around a single pain target, without taking into account various social interactions with the observers. Our findings support the idea that pain perception models should be extended, taking into account some psychological characteristics of observers. Our conclusions are on the basis of advanced statistical methods.

Minimal humanity cues induce neural empathic reactions towards non-human entities

The present study tested whether the attribution of humanness by means of a minimal humanity cue is sufficient for the occurrence of empathic neural reactions towards non-human entities that are painfully stimulated. Vegetables have been used as a control condition to explore empathy towards humans’ pain before. In the context of the present study, they were given a minimal humanity cue (i.e., a human name) or not (i.e., an adjective). Human associations with these different types of vegetables were measured and where either represented: pricked by a needle (painful condition) or touched by a Q-tip (touch condition) while recording electroencephalographic activity from a sample of 18 healthy students. Event-related potentials (ERP) indicated that those participants classified as high humanizers, showed an increased neural reaction when vegetables with a name were painfully rather than neutrally stimulated compared to vegetables without a name. These reactions occurred both in an early (P2: 130–180 ms) and a later (P3: 360–540 ms) ERP time-window. Moreover, this differential reaction on the P3 significantly correlated with participants’ explicit empathic tendencies. Overall, these findings suggest that empathy can be triggered for non-human entities as long as they are seen as minimally human.

Dynamic cutaneous information is sufficient for precise curvature discrimination.

Our tactual perceptual experiences occur when we interact, actively and passively, with environmental objects and surfaces. Previous research has demonstrated that active manual exploration often enhances the tactual perception of object shape. Nevertheless, the factors that contribute to this enhancement are not well understood. The present study evaluated the ability of 28 younger (mean age was 23.1 years) and older adults (mean age was 71.4 years) to discriminate curved surfaces by actively feeling objects with a single index finger and by passively feeling objects that moved relative to a restrained finger. While dynamic cutaneous stimulation was therefore present in both conditions, active exploratory movements only occurred in one. The results indicated that there was a significant and large effect of age, such that the older participants’ thresholds were 43.8 percent higher than those of the younger participants. Despite the overall adverse effect of age, the pattern of results across the active and passive touch conditions was identical. For both age groups, the curvature discrimination thresholds obtained for passive touch were significantly lower than those that occurred during active touch. Curvature discrimination performance was therefore best in the current study when dynamic cutaneous stimulation occurred in the absence of active movement.

Sensory Perception of Material Texture in Consumer Products

A more informed understanding of information about human sensory perception of materials is playing an increasingly important role in the selection and combination of materials within manufactured products. An initial perception of a product may be based on sensory properties such as colour, texture, sound, smell, and taste. Designers use textures within most of their design practices and understand that texture and texture combination can have a strong visual and tactile impact. The visual aesthetics of a particular material and the surface texture information are signalled through visual and tactile feedback. This contributes to how the user perceives the ‘material representation’ (which is defined as: the perceived images, properties, meanings, and values of a material in the human–product interface under a specific set of environmental conditions).Prior scholarship is limited with regard to information about the sensory and aesthetic characteristics of materials. Hence previous work reported by the authors of this paper has focused mainly on material texture through visual and tactile feedback. By carrying out controlled experimental research on texture, using specially prepared material samples, a dimension–lexicon system was used to subjectively describe a material texture by touch. Slight differences in the descriptive lexicons used were analysed in terms of gender, material surface finish, sensory conditions, and control groups. Further research revealed correlations between various subjective responses within the texture perception dimensions. In parallel, through experimental testing, the quantitative relationships between subjective response to texture and the objective physical parameters of materials were also reported. An understanding of these correlations assisted in the selection of better-matching material texture combinations.In this work the application of previous research results in design practice has been achieved as a result of collaboration with a leading UK manufacturer of hairdryers. Contextual research on material sensory perception and its influence on the whole product has been undertaken. This paper introduces the research methodology, the research results, and discussion from this research. Five typical hairdryers of the same brand varied in materials and textures were selected as product samples to be operated and evaluated by 25 participants, under controlled visual–touch conditions, simulating a typical operating process for the product. The contents of evaluation covered the sensory, functional, emotional, and associative responses to the whole product but with focus on the handle for each hairdryer. The relationship between these responses is discussed, the influencing factors for a good handle (e.g. comfort) are analysed, and suitable materials/textures are suggested. The results not only provide recommendations for further improvement and development of the products for our collaborative company, but also give insights on materials/texture selection for a wider range of consumer products where handle grip and perceived comfort and control are important factors for creating a positive user experience.

A case of somatopsychic depersonalization in schizotypal disorder: A multimodal approach

Background In the general concept of self-disturbances in schizophrenia and schizophrenia spectrum disorders, somatopsychic depersonalization (SPD) occupies a special place, as it constitutes a syndrome that comprises feelings of detachment from one's own body and mental processes. However, apart from clinical descriptions, to date the pathophysiology of SPD is not fully understood due to the rareness of the syndrome and a lack of experimental studies. Methods In a case study of one patient with schizotypal disorder (M.M., male, 29 y.o.), we applied a multimodal evaluation (phenomenological, neuropsychological, behavioural, application of fMRI paradigm) in order to understand the SPD phenomena. Results The patient's clinical profile was identified as disruption of implicit bodily function, accompanied by depressive symptoms. On a neuropsychological level, the patient exhibited impairment in executive functioning, intact tactile perception and kinesthetic praxis. Behavioral tests revealed an altered sense of time but unimpaired self-agency. Furthermore, the patient exhibited a lack of empathy and he had autistic traits, although with a sufficient ability to verbalize his feelings. On the neurobiological level using an active and passive touch paradigm during functional magnetic resonance imaging (fMRI), we found a hyperconnectivity of the default-mode network and salience network and a hypoconnectivity of the central executive brain networks in the performance of the touch task as well as intact perceptual touch processing emerging from the direct comparisons of the touch conditions. Conclusions Our data provide evidence for the important role of altered large-brain network functioning in SPD that corresponds to the specific behavioral and neurocognitive phenomena.

Light finger contact concurrently reduces postural sway and enhances signal detection performance in children with developmental coordination disorder

The current study examined the effects of light finger touch on postural sway and signal detection performance in children with developmental coordination disorder (DCD). Children with DCD (n=30; 18 boys, 12 girls; age=11.87±0.48 years) and typically developing children (n=30; 14 boys, 16 girls; age=11.73±0.52 years) were recruited from schools in Pintung County, Taiwan. Participants completed a signal detection task under no finger touch (NT) and light finger touch (LT) conditions, while postural sway in both anteroposterior (AP) and mediolateral (ML) axes was recorded. In both conditions, children with DCD exhibited significantly higher levels of postural sway (p<0.05) and lower signal detection performances (p<0.05) than TDC. Additionally, both groups significantly reduced postural sway (p<0.05) and enhanced signal detection performance (p<0.05) when engaged in light finger touch compared with no finger touch. While the effect of LT on postural sway was greater among TDC relative to children with DCD (p<0.05), the effect of LT on signal detection was greater in children with DCD compared with TDC (p<0.05). These results suggest that light finger touch is effective in concurrently reducing postural sway and enhancing signal detection in both groups.

Interpersonal stroking touch is targeted to C tactile afferent activation

C tactile fibers are a specialized group of fibers innervating the non-glabrous skin that are tuned to light gentle stroking applied with velocities between 1 and 10cm/s. Those fibers add to the sensation of interpersonal caressing and pleasant touch. It is unclear whether people spontaneously apply touch that is tuned to optimally activate those fibers. This was investigated in three studies. In study one, 45 participants (21.8±2.3 years, 24 women) were asked to stroke an artificial arm. In study two, 32 participants (28.3±8.7years, 16 women) were asked to stroke their partner. In study three, 11 parents (29.4±5.7years, 6 women) were asked to stroke their babies. Stroking velocity was tracked in all conditions. Stroking velocities were significantly slower in the partner touch and baby touch condition than in the artificial arm condition and all of the participants stroking their partner or baby used velocities that can activate C tactile fibers. We conclude that human social stroking is optimized for C tactile stimulation.

A light fingertip touch reduces postural sway in children with autism spectrum disorders

This study examined the effects of a light fingertip touch on postural control in children with autism spectrum disorders (ASD) and typically developing children (TDC). MethodsWe recruited 16 children with ASD (age=11.041±1.275), and 16 TDC (age=10.966±1.166 years). A force platform measured postural sway in the anteroposterior (AP) and mediolateral (ML) directions under light fingertip touch (LT) and no touch (NT) conditions, with both eyes open (EO) and both eyes closed (EC). As a summary of the experimental conditions, ML sway was significantly greater in the ASD group than in the TDC group. Also, results showed a significant reduction in postural sway in the ML direction in the LT condition compared with the NT condition. These effects applied to both the EO and EC conditions. Lastly, the reduction in ML sway between the NT and LT conditions was significantly greater in the ASD than the TDC group. ConclusionThe effects of a light fingertip touch on reducing postural sway appear more efficient in children with ASD compared with TDC. These findings suggest that a light fingertip touch may be of clinical and practical importance, and provides a useful means of enhancing postural stability in children with ASD.

Evaluation of a portable markerless finger position capture device: accuracy of the Leap Motion controller in healthy adults

Although motion analysis is frequently employed in upper limb motor assessment (e.g. visually-guided reaching), they are resource-intensive and limited to laboratory settings. This study evaluated the reliability and accuracy of a new markerless motion capture device, the Leap Motion controller, to measure finger position. Testing conditions that influence reliability and agreement between the Leap and a research-grade motion capture system were examined. Nine healthy young adults pointed to 15 targets on a computer screen under two conditions: (1) touching the target (touch) and (2) 4 cm away from the target (no-touch). Leap data was compared to an Optotrak marker attached to the index finger. Across all trials, root mean square (RMS) error of the Leap system was 17.30 ± 9.56 mm (mean ± SD), sampled at 65.47 ± 21.53 Hz. The % viable trials and mean sampling rate were significantly lower in the touch condition (44% versus 64%, p < 0.001; 52.02 ± 2.93 versus 73.98 ± 4.48 Hz, p = 0.003). While linear correlations were high (horizontal: r2 = 0.995, vertical r2 = 0.945), the limits of agreement were large (horizontal: −22.02 to +26.80 mm, vertical: −29.41 to +30.14 mm). While not as precise as more sophisticated optical motion capture systems, the Leap Motion controller is sufficiently reliable for measuring motor performance in pointing tasks that do not require high positional accuracy (e.g. reaction time, Fitt’s, trails, bimanual coordination).

Postural stabilization effects of light touch do not come from axis-specific cues of postural sway: a pilot study.

A light finger touch can stabilize posture despite it not providing enough force to create mechanical support. The underlying mechanism may be due to the finger touch providing information in the axis with the greatest instability. The most appropriate way to test this hypothesis is a dual-axis paradigm, i.e., to remove sway-related information from touch in either anterior-posterior (AP) or medio-lateral (ML) axis and then measure postural sway in both axes when the standing posture is equally unstable in AP and ML axes. In this study, 16 participants stood in a feet-together stance, and center of pressure in both axes was measured. Apart from No touch and Stable conditions, the touch surface was manipulated to move in close synchrony with postural sway so as to remove information regarding postural sway in one axis (AP Sway-referenced) or two axes (AP-ML Sway-referenced). The results showed that AP Sway-referenced condition stabilized posture in both axes, whereas AP-ML Sway-referenced condition did not stabilize posture in either axis. The pilot results indicated that touch effects do not come from axis-specific sensory cues of postural sway.

Direct writing on paper of foldable capacitive touch pads with silver nanowire inks.

Paper-based capacitive touch pads can be fabricated utilizing high-concentration silver nanowire inks needle-printed directly onto paper substrates through a 2D programmable platform. Post deposition, silver nanowire tracks can be photonically sintered using a camera flash to reduce sheet resistance similar to thermal sintering approaches. Touch pad sensors on a variety of paper substrates can be achieved with optimized silver nanowire tracks. Rolling and folding trials, which yielded only modest changes in capacitance and no loss of function, coupled with touch pad functionality on curved surfaces, suggest sufficient flexibility and durability for paper substrate touch pads to be used in diverse applications. A simplified model to predict touch pad capacitance variation ranges with differing touch conditions was developed, with good agreement against experimental results. Such paper-based touch pads have the advantage of simple structure, easy fabrication, and fast sintering, which holds promise for numerous commercial applications including low-cost portable devices where ultrathin and lightweight features, coupled with reliable bending stability are desirable.

Algorithm for improving SNR using high voltage and differential Manchester code for capacitive touch screen panel

An algorithm for a capacitive touch screen panel that can make the sum of the signal into `0' for the use of high voltage is presented. The differential Manchester code is combined with the Walsh-Hadamard code to generate an input coded signal. Owing to the property of the differential Manchester code, the Moore-Penrose pseudoinverse matrix is employed to decode-mutual capacitance from the received signal. As only the variation between the un-touch and touch condition is detected at the receiver, a high-voltage input coded signal is used. Unlike a normal touch system, the decoded sensing capacitance in the proposed algorithm does not have an absolute value. Positive decoded capacitance is the un-touch condition and negative decoded capacitance is the touch condition. The simulated signal-to-noise ratio (SNR) of the proposed algorithm is 27.9 dB, which is 8.26 dB higher than SNR in not return to zero (NRZ).

The effect of friendly touch on delay-of-gratification in preschool children

Physical touch has many documented benefits, but past research has paid little attention to the effects of touch on children's development. Here, we tested the effect of touch on children's compliance behaviour in a modified delay-of-gratification task. Forty children (M = 59 months) were randomly assigned to a touch or no touch group. Children in the intervention condition received a friendly touch on the back while being told that they should wait for permission to eat a candy. Results showed that children in the touch condition waited an average of two minutes longer to eat the candy than children in the no touch condition. This finding has implications for the potential of using touch to promote positive behaviours in children.

Effects and after-effects of voluntary intermittent light finger touch on body sway

Effects of light touch on body sway have usually been investigated with some form of constant contact. Only two studies investigated transient sway dynamics following the addition or withdrawal of light touch. This study adopted a paradigm of intermittent touch and assessed body sway during as well as following short periods of touch of varying durations to investigate whether effects and after-effects of touch differ as a function of touch duration. In a modified heel-to-toe posture, 15 blindfolded participants alternated their index finger position between no-touching and touching on a strain gauge in response to low- and high-pitched auditory cues. Five trials of 46s duration were segmented into 11 sections: a 6-s no-touching period was followed by five pseudo-randomly ordered touching periods of 0.5-, 1-, 1.5-, 2-, and 5-s duration, each of which was followed by another 6-s no-touching interval. Consistent with previous research, compared to no-touching intervals sway was reduced during touch periods with touch durations greater than 2s. Progressive reductions in sway were evident after touch onset. After touch withdrawal in the 2-s touch condition, postural sway increased and returned to baseline level nearly immediately. Interestingly, in the 5-s touch condition, reductions in sway persisted even after touch withdrawal in the medio-lateral and antero-posterior plane for around 2.5s and 5.5s, respectively. Our intermittent touch paradigm resulted in duration-dependent touch effects and after-effects; the latter is a novel finding and may result from a more persistent postural set involved in proactive sway control.

38.1: A Low‐Power Fast Readout Circuit using a Dual‐Mode Sensing Algorithm for Medium‐Size Capacitive Touch Screen Panels

AbstractA new readout circuit architecture for capacitive touch screen panels (TSPs) is introduced to enhance the reporting rate and to improve the signal to noise ratio (SNR) with low power consumption. The proposed Dual‐Mode Sensing (DMS) method finds the actual touch spots without feedback from the TSP to the MCU. In addition, the effect of noise coupled to the touch signal is reduced owing to the averaging effect of the proposed continuous‐time integration (CTI) technique. The circuit was designed for a 0.35 μm CMOS technology. The proposed sensing scheme shows a 257 Hz reporting rate under a simultaneous 10 touch condition on a 10.1 inch TSP, providing a 33 dB SNR with power consumption of 679 μW from a 3.3V supply.

Haptic perception mechanism of softness – second report, relationship between stiffness of an object and softness sensation

A palpation is a useful method to detect cancer and to evaluate skin or under skin conditions. However, the palpation is a skillful method. Doctor's mental and physical conditions affect diagnoses by the palpation. Additionally, it is hard to share the feeling of palpation with other people because palpation is subjective skill. Therefore, the development of the sensor that can measure the skin and under skin condition of the body like softness as a doctor's palpation is demanded. In this paper, we focus on a haptic perception mechanism of human for evaluating the softness. Six objects are made to conduct sensory tests. The silicone rubber part of the objects has two kinds of thickness and three kinds of Young's modulus. Relationships between physical properties of evaluated objects and the softness that human feel in active touch are investigated. After that, to control the contact condition between objects and finger, a passive touch evaluation system is fabricated. Using the system, relationships between the stiffness of the objects and evaluated haptic softness are investigated under passive touch condition.