Hedonic Responses to Touch are Modulated by the Perceived Attractiveness of the Caresser.

Abstract Previous research has shown that a specific type of C fiber, the C tactile afferents, are involved in detecting gentle, dynamic tactile stimuli on the skin, giving rise to affective responses in the central nervous system. Despite building on such bottom-up information flow, the hedonic perception and the physiological consequences of affective touch are influenced by various sources of top-down information. In the present study we investigated how perception of affective touch is influenced by the attractiveness of hypothetical caressers. Participants were stroked on the arm and the palm while looking at photos of high attractive and low attractive opposite-gender faces, and were instructed to imagine those people as the caressers. In a control condition no photo was paired with the touch. The stroking stimulation was delivered with a soft brush either on the forearm or on the palm, and either with a slower or faster speed. Participants rated the pleasantness of each stimulation, while electrocardiographic recordings were made to extract heart rate variability data. Results showed that participants preferred touch stimuli paired with high attractive faces; they also preferred palm stroking and slower stroking speed. Like subjective pleasantness ratings, heart rate variability responses to affective touch (slow) were higher for high attractive than for low attractive caressers, but were not selective for arm or palm stroking. Overall, the present study confirms that contextual social information plays a major role in affective touch experiences, influencing not only the hedonic quality of the experience but also the physiological state of the body

Three-dimensional telomere profiles in papillary thyroid cancer variants: A pilot study

Besides the two main histologic types of papillary thyroid carcinoma (PTC), the classical PTC (CL-PTC) and the follicular variant PTC (FV-PTC), several other variants are described. The encapsulated FV-PTC variant was recently reclassified as noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) due to its similarities to benign lesions. Specific molecular signatures, however, are still unavailable. It is well known that improper DNA repair of dysfunctional telomeres may cause telomere-related genome instability. The mechanisms involved in the damaged telomere repair processing may lead to detrimental outcomes, altering the three-dimensional (3D) nuclear telomere and genome organization in cancer cells. This pilot study aimed to evaluate whether a specific 3D nuclear telomere architecture might characterize NIFTP, potentially distinguishing it from other PTC histologic variants. Our findings demonstrate that 3D telomere profiles of CL-PTC and FV-PTC were different from NIFTP and that NIFTP more closely resembles follicular thyroid adenoma (FTA). NIFTP has longer telomeres than CL-PTC and FV-PTC samples, and the telomere length of NIFTP overlaps with that of the FTA histotype. In contrast, there was no association between BRAF expression and telomere length in all tested samples. These preliminary findings reinforce the view that NIFTP is closer to non-malignant thyroid nodules and confirm that PTC features short telomeres

The arousing power of everyday materials: an analysis of the physiological and behavioral responses to visually and tactually presented textures

Previous research has shown that during multisensory perception, vision frequently dominates over the other sensory modalities. However, it is still unclear whether sensory dominance also implies the generation of a greater state of arousal. Here, we assess the psycho-physiological reactions to different materials when presented tactually (Group 1) or visually (Group 2). In Group 1, the participants’ forearm was stroked with different textures (satin, tinfoil, leather, sandpaper and abrasive sponge), by either a male or a female experimenter. The speed of stimulation was set to elicit a vigorous response of C-tactile afferents, involved in the perception of the more pleasant aspects of touch. The participants were asked to rate the pleasantness of the stimulation. In Group 2, the same textures were presented only visually, and the participants were asked to rate the imagined pleasantness of being touched by those stimuli. Skin conductance responses were recorded in both groups. The results revealed that the tactile presentation of the stimuli led to higher skin conductance responses than the visual presentation; this difference was higher for women than for men. Smooth materials were perceived as more pleasant than rough materials, but no differences in terms of skin conductance responses were found among them. Moreover, the textures were rated as less pleasant when presented visually than when presented tactually. These findings are relevant to understand how physiological arousal is modulated by different senses and to elucidate the mechanisms involved in hedonic tactile perception

Stroking and tapping the skin: behavioral and electrodermal effects

Being caressed represents one of the most typical expressions of affection conveyed by touch. Converging evidence suggests that the pleasant perception of gentle and slow stroking delivered to the hairy skin is mediated by C-Tactile afferents (CTs). While behavioral and neural responses to CT-optimal touch have been moderately explored so far, less is known about the autonomic reaction to different kinds of touch (both CT-optimal and not). Here, we investigated whether physiological arousal varies as a function of the specific tactile stimulation provided. Stroking (slow: 3 cm/s ‘CT-optimal’; or fast: 30 cm/s) and tapping (random or fixed spatial order) stimulations were delivered to the participants’ forearm with a brush, for durations of 9 or 60 s. Participants’ skin conductance response (SCR) and level (SCL), as well as subjective evaluations, were recorded. The results revealed that being stroked (at both the velocities) induced higher SCR and SCL than being tapped. Moreover, while higher SCR was elicited by CT-suboptimal stroking compared to CT-optimal stroking, SCL was not affected differently by CT-optimal touch. No differences were found between the effects of 9 and 60 s stimulations. Slow stroking was evaluated as the most pleasant, relaxing and ‘social’ type of touch compared to the other tactile stimulations. Taken together, these findings shed light on the psychophysiological responses to stroking (including CT-optimal touch) and tapping, and contribute to elucidate the mechanisms underlying hedonic tactile perception

Textures that we like to touch: An experimental study of aesthetic preferences for tactile stimuli

We report two experiments designed to investigate the nature of aesthetic preferences for tactile textures in humans. In Experiment 1, the participants rated their preference for a range of actively and passively explored textures presented on their hands and on their cheeks. The results revealed that those textures that were subjectively-rated as smoother were preferred over those that were rated as rougher. Moreover, certain textures were disliked more during active than during passive stimulation. In Experiment 2, the speed of tactile stimulation was controlled in order to elicit vigorous responses from C-tactile fibers (present only in hairy skin), which are thought to play a central role in pleasant aspects of touch. The results revealed that textures were preferred when presented on the hairy skin of the forearm than on the glabrous palm of the hand. These results provide preliminary evidence regarding people's preferences for different attributes of tactile surface

The Effect of the Tactile Attributes of a Container on Mineral Water Perception

The present study investigates the effect of container texture on people’s perception of four characteristics (i.e., freshness, pleasantness, level of carbonation, lightness) of mineral water (i.e., still or carbonated). Water was served in three commercial cups covered with a layer of sandpaper, satin, or the same material of the cup (plastic). The blindfolded participants were asked to evaluate the mineral water using visual analogue scales. The results showed that mineral water was perceived as fresher and more pleasant when contained in plastic cups than when it was contained in cups covered with sandpaper or satin. Moreover, mineral water was perceived as lighter when contained in plastic cups than when it was contained in cups covered with sandpaper. These results suggest that people’s perception of some characteristics of mineral water can be modulated by the texture of the container in which the liquid is served

The individual preferred velocity of stroking touch as a stable measurement

Affective touch is of fundamental importance in human social interactions and there is an increasing interest in using touch as a probe for general affective perception. To this end, we developed a test of preferred velocity (ToP-V) of touch and tested whether the individually preferred stroking velocity is a stable and valid measurement. In study one, thirty healthy participants (18–30 years, 17 women) were examined with the ToP-V. Therefore, pairs of different slow stroking stimuli were presented by the Rotary Tactile Stimulator – a robotic device - on the forearm and the participants chose the velocity they preferred in a forced choice paradigm. A retest was conducted after about 12 days. In study two, twenty-two healthy participants (20–43 years, 11 women) were tested with a shorter version of the ToP-V on the forearm and also on the palm. Moreover, they rated the pleasantness and the intensity of the stroking stimulations on both body sites. Results suggest that humans possess an individual and stable preferred velocity of stroking touch (test-retest reliability r = 0.86) which can be tested in a standardized procedure. A shortened 5 min version of the ToP-V also exhibited reasonable test characteristics (split half reliability: r = 0.7; test-retest reliability r = 0.77). The ToP-V correlated well with the pleasantness ratings when tested on the forearm (r = 0.65), but not when tested on the palm (r = − 0.22), indicating that the ToP-V targets a C-tactile nerve fiber specific perception. Hence, the ToP-V can be used for reliably probing affective touch perception

The effect of visual and auditory information on the perception of pleasantness and roughness of virtual surfaces

Despite the large number of studies on the multisensory aspects of tactile perception, very little is known regarding the effects of visual and auditory sensory modalities on the tactile hedonic evaluations of textures, especially when the presentation of the stimuli is mediated by a haptic device. In this study, different haptic virtual surfaces were rendered by varying the static and dynamic frictional coefficients of a Geomagic® Touch device. In Experiment 1, the haptic surfaces were paired with pictures representing everyday materials (glass, plastic, rubber and steel); in Experiment 2, the haptic surfaces were paired with sounds resulting from the haptic exploration of paper or sandpaper. In both the experiments, participants were required to rate the pleasantness and the roughness of the virtual surfaces explored. Exploration times were also recorded. Both pleasantness and roughness judgments, as well as the durations of exploration, varied as a function of the combinations of the visuo-tactile and the audio-tactile stimuli presented. Taken together, these results suggest that vision and audition modulate haptic perception and hedonic preferences when tactile sensations are provided through a haptic device. Importantly, these results offer interesting suggestions for designing more pleasant, and even more realistic, multisensory virtual surfaces