Validation of "Neurit.Space": Three Digital Tests for the Neuropsychological Evaluation of Unilateral Spatial Neglect.

Patients suffering from Unilateral Spatial Neglect (USN) fail to pay attention to, respond to, and report sensory events occurring in the contralesional side of space. The traditional neuropsychological assessment of USN is based on paper-and-pencil tests, whose data recording and scoring may be subjected to human error. The utilization of technological devices can be expected to improve the assessment of USN. Therefore, we built Neurit.Space, a modified digital version of three paper-and-pencil tests, widely used to detect signs of USN, namely: Bells Cancellation, Line Bisection and Five Elements Drawing Test. Administration and data processing is fully automatic. Twelve right brain-damaged patients (six with and six without USN) and 12 age- and education-balanced healthy participants were enrolled in the study. All participants were administered both the computerized and the paper-and-pencil versions of the tests. The results of this preliminary study showed good sensitivity, specificity, and usability of Neurit.Space, suggesting that these digital tests are a promising tool for the evaluation of USN, both in clinical and in research settings.

The Neuropsychological Assessment of Unilateral Spatial Neglect Through Computerized and Virtual Reality Tools: A Scoping Review.

Unilateral Spatial Neglect is a disabling neuropsychological deficit. Patients with spatial neglect fail to detect and report events, and to perform actions in the side of space contralateral to a hemispheric cerebral lesion. Neglect is assessed by evaluating the patients' abilities in daily life activities and by psychometric tests. Computer-based, portable and Virtual Reality technologies may provide more and precise data, and be more sensitive and informative, compared to current paper-and-pencil procedures. Studies since 2010, in which such technologies have been used, are reviewed. Forty-two articles meeting inclusion criteria are categorized according to their technological approaches (computer-, graphics tablet or tablet-, virtual reality-based assessment, and other). The results are promising. However, a definite golden standard, technologically based procedure cannot be still established. Developing technologically based tests is a laborious process, which requires technical and user experience improvements as well as normative data, to increase the evidence of efficacy for clinical evaluation of at least some of the tests considered in this review.

An Exploratory Study on the Effect of Virtual Environments on Cognitive Performances and Psychophysiological Responses.

Research shows that reduced exposure to natural contexts is associated with an increase in psychophysical disorders. Recent evidence suggests that even a brief experience in natural scenarios can positively affect people's health and well-being. However, natural contexts are not always easily accessible. This study investigates the effects of natural and indoor virtual environments (VREs) on psychophysiological and cognitive responses. Following a within-subject design, 34 healthy participants were exposed to two VREs (i.e., a forest and a living room) in a counterbalanced order through a head-mounted display (Oculus Rift). Participants were asked to explore the scenarios and execute a modified version of the Paced Auditory Serial Addition Test. Physiological parameters (heart rate, skin conductance level [SCL], and respiration rate) were recorded during the whole session. After the exposure to VREs, participants filled a set of visual analog scales to rate their subjective experience of presence, relaxation, and stress. Participants reported a higher perceived sense of relaxation in the virtual forest. Moreover, their SCLs were significantly higher in this environment, showing that the forest elicited higher physiological arousal than the living room. Furthermore, their SCLs were significantly higher during the attentional task in the virtual living room. The results suggest that a natural virtual environment can make people feel more relaxed and physiologically engaged than an indoor scenario. The latter instead can be linked to a performing venue, as reported for real contexts. However, these changes were not related to modulations of attentional performance.

The impact of contextual information regarding the origin of food on consumers' judgments.

Explicit and implicit responses to food and beverage are known to be modulated by expectations generated by contextual factors. Among these, labelling regarding the country of origin has been systematically shown to impact on consumers' evaluations of products. However, it is not clear yet whether the presence of food origin biases also affects humans' physiological (i.e., implicit) responses, as well as whether different conditions of sensory appreciation of products are equally influenced. The present preliminary study investigated the psychophysiological responses to food samples paired to labels of declared (i.e., Italy, Spain/Germany, EU) or undeclared origins. Food items (i.e., olives and cracker) were presented in visual or taste conditions to thirty Italian participants, whose behavioral (i.e., liking, willingness to buy, and estimated cost) and physiological (i.e., skin conductance responses) responses were collected. The results indicated that the food samples elicited stronger liking and willingness to buy responses by participants and were estimated as more expensive, when being firstly experienced through vision than taste. No differences in the physiological arousal state were found as a function of food origin or sensory condition of presentation.

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

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.

Socially-relevant Visual Stimulation Modulates Physiological Response to Affective Touch in Human Infants.

The human tactile system is known to discriminate different types of touches, one of these termed 'affective touch', is mainly mediated by slow conducting tactile afferents (CT fibres), which are preferentially activated by slow and gentle strokes. Human infants experience self-generated tactile stimulation during prenatal life, and they receive a large amount of affectionate touches by their caregivers from birth. This early and extended experience with tactile stimulation may likely make infants particularly sensitive to affective touch, and increasing evidence shows that this may indeed be the case. However, infants commonly experience affective touch in the context of social interactions with familiar adults (e.g., while looking at their caregiver), and recent evidence suggests that this helps them assigning affiliative and communicative meaning to the touch they are perceiving. Here we investigated the presence of visual-tactile interactions in 4-5-month-old infants' physiological (i.e., skin conductance) and behavioural (i.e., visual looking times) responses to visual and tactile stimulation of affective/social nature when the sources of both stimulation are not familiar to the infant. To explore whether the modulation of physiological arousal elicited by the socially-relevant bimodal stimulation is specific to infants or extends into adulthood, we also tested a group of adults. Infants (N = 25) and adults (N = 25) were stimulated on their forearm through slow stroking (i.e. affective touch) or tapping (i.e. non-affective touch) during the observation of dynamic images of socially-relevant (i.e., an unfamiliar face) and non-socially-relevant (i.e., a house) stimuli. We found that the simultaneous presentation of socially-relevant visual-tactile stimuli significantly decreased infants' - but not the adults' - electrodermal response, suggesting that infants easily integrate low-level properties of affective touch with socially salient visual information, and that social experience may tune and change sensitivity to affective touch across the life-span.

Conveying trunk orientation information through a wearable tactile interface.

We present the design and test of a wearable device capable to detect the user's trunk orientation with respect to the gravitational field and to provide tactile stimulation to correct tilted positions. Vibrations are delivered to the shoulders, the frontal and dorsal parts of the trunk, by using the human body as an indicator of the four cardinal directions. The device was experimentally tested in normal gravity conditions by thirty-nine volunteers. The efficacy of tactile cues was investigated in comparison to visual and visuo-tactile cues. The results revealed that, despite the fact that the time needed to complete the task was shorter when people were guided by visual signals, the tactile cues were equally informative and, in some cases, the trunk spatial orientation was even more accurate. Overall, tactile cues were evaluated by users as more intuitive, effective and accurate.

Emotional visual stimuli affect the evaluation of tactile stimuli presented on the arms but not the related electrodermal responses.

Considering the wealth of recent studies on affective touch, to date, little research addressed the role of the other sensory modalities in the modulation of hedonic tactile perception. Here, we investigated the behavioral and electrodermal signature of the interaction between simultaneously presented visual and tactile stimuli. In three experiments, participants were presented with emotional pictures (international affective picture system; IAPS), while their forearm was gently stroked by means of different tactile textures (i.e., sandpaper, satin, tinfoil, abrasive sponge, and skin-to-skin contact). In Experiment 1, the participants evaluated the pleasantness of the tactile stimulation received, while in Experiment 2 they evaluated the pictures emotional valence. In Experiment 3 the participants rated the pleasantness, the smoothness and the softness of the textures; skin conductance responses (SCRs) were also measured. In sum, the results revealed that while the visual valence ratings were not modulated by the tactile stimulation, the hedonic and sensory tactile ratings were modulated by the visual presentation of both positively and negatively valenced pictures, as well as by neutral pictures. The modulatory effects occurring during visuo-tactile interactions might thus be not necessarily reciprocal. Moreover, the SCRs were not differently affected by the visuo-tactile or tactile conditions of stimulus presentation, suggesting a dissociation between behavioral and electrodermal effects in multisensory interactions.

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.

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 evaluation 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.

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 (18-30years, 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 12days. In study two, twenty-two healthy participants (20-43years, 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 5min 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.

When Sandpaper Is 'Kiki' and Satin Is 'Bouba': an Exploration of the Associations Between Words, Emotional States, and the Tactile Attributes of Everyday Materials.

Over the last decade, scientists working on the topic of multisensory integration, as well as designers and marketers involved in trying to understand consumer behavior, have become increasingly interested in the non-arbitrary associations (e.g., sound symbolism) between different sensorial attributes of the stimuli they work with. Nevertheless, to date, little research in this area has investigated the presence of these crossmodal correspondences in the tactile evaluation of everyday materials. Here, we explore the presence and nature of the associations between tactile sensations, the sound of non-words, and people's emotional states. Samples of cotton, satin, tinfoil, sandpaper, and abrasive sponge, were stroked along the participants' forearm at the speed of 5 cm/s. Participants evaluated the materials along several dimensions, comprising scales anchored by pairs of non-words (e.g., Kiki/Bouba) and adjectives (e.g., ugly/beautiful). The results revealed that smoother textures were associated with non-words made up of round-shaped sounds (e.g., Maluma), whereas rougher textures were more strongly associated with sharp-transient sounds (e.g., Takete). The results also revealed the presence of a number of correspondences between tactile surfaces and adjectives related to visual and auditory attributes. For example, smooth textures were associated with features evoked by words such as 'bright' and 'quiet'; by contrast, the rougher textures were associated with adjectives such as 'dim' and 'loud'. The textures were also found to be associated with a number of emotional labels. Taken together, these results further our understanding of crossmodal correspondences involving the tactile modality and provide interesting insights in the applied field of design and marketing.

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.

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.