Haptic Illusion Research Articles

Have I Been Touched? Subjective and Objective Aspects of Tactile Awareness.

Somatosensory tactile experience is a key aspect of our interaction with the environment. It is involved in object manipulation, in the planning and control of actions and, in its affective components, in the relationships with other individuals. It is also a foundational component of body awareness. An intriguing aspect of sensory perception in general and tactile perception in particular is the way in which stimulation comes to consciousness. Indeed, although being aware of something seems a rather self-evident and monolithic aspect of our mental states, sensory awareness may be in fact modulated by many different processes that impact on the mere stimulation of the skin, including the way in which we perceive our bodies as belonging to us. In this review, we first took into consideration the pathological conditions of absence of phenomenal experience of touch, in the presence of implicit processing, as initial models for understanding the neural bases of conscious tactile experience. Subsequently, we discussed cases of tactile illusions both in normal subjects and in brain-damaged patients which help to understand which high-order processes impact tactile awareness. Finally, we discussed the observations reported in the review in light of some influential models of touch and body representation.

Phantom sensation: Threshold and quality indicators of a tactile illusion of motion

Utilizing a randomized, blind, controlled experiment, and the ascending method of limits, we determined the minimum amplitude of motion at which individuals perceive a tactile illusion called moving phantom sensation, the perceived level of clarity and continuity of motion. Implementing tactile illusions in virtual/augmented reality, sensory substitution systems, and other human–computer interaction technologies results in interfaces with improved resolution, using two vibrating actuators only. The actuators are attached to the skin in different locations to render a moving phantom sensation. The intensity of vibrations increases in one actuator while decreases in the other according to the envelope of the voltage supply signals. This intensity variation creates the illusion of a vibrating point moving between the actuators. We gradually increased the amplitude of motion until the participant reported perceiving the illusion, for eight values of duration of the stimulus from 0.1 to 6.0 s. Participants perceived the illusion at a minimum amplitude of motion of 20%; being 100% the motion from one actuator to the other. The median level of clarity of the perceived illusion at the minimum amplitude of motion was 2 (not so clear). Finally, we found a positive correlation between duration and continuity of motion.

Multimodality In Stop Motion Animation Films

Stop motion animation films use a complicated process of giving life to inanimate objects through visuals and cinematic experience that are created by using puppets made of clay, resin, silicon, wool etc. In the world of digital communication and technology, there has been rise of using multiple modes in order to give deeper meaning to the visuals of a film. Today, apart from language, stop animation film uses various semiotic modes of sound, music, visual metaphors, set design, camera angles, color theory, gestural, spatial and haptic illusion that helps in disseminating ideas, and concepts that are difficult to communicate through a film. The researcher has conducted a content analysis of three Oscar Nominated stop motion animation films including Negative Space, Sister and Lost and Found to identify the various semiotic modes used in the narrative of the film and a quantitative study was conducted to investigate the perception of the young adults including college students of undergraduate and post graduates and professionals between age group of (18-24) living in Mumbai regarding these modes.

Pressure Stimuli and Spatiotemporal Illusions on the Forearm.

To design complex wearable haptic interfaces using pressure, we have to explore how we can use pressure stimuli to their full potential. Haptic illusions, such as apparent motion and apparent location, can be a part of this. If these illusions can be evoked with pressure, haptic patterns can increase in complexity without increasing the number of actuators or combining different types of actuators. We did two psychophysical experiments with pressure stimuli on the forearm using a pneumatic sleeve with multiple, individually controlled McKibben actuators. In Experiment 1, we found that spatial integration of two simultaneously presented stimuli occurred for distances up to 61 mm. In Experiment 2, we found that apparent motion can be elicited with distinct pressure stimuli over a range of temporal parameters. These results clearly show spatio-temporal integration in the somatosensory system for pressure stimuli. We discuss these findings in relation to effects found for vibration and the mechanoreceptors in the glabrous skin.

A Comparative Investigation of Cutaneous Rabbit and Funneling Tactile Illusions for Implementation in Vibrotactile Displays

A Comparative Investigation of Cutaneous Rabbit and Funneling Tactile Illusions for Implementation in Vibrotactile Displays

Thermal illusions for thermal displays: a review.

Thermal illusions, a subset of haptic illusions, have historically faced technical challenges and limited exploration. They have been underutilized in prior studies related to thermal displays. This review paper primarily aims to comprehensively categorize thermal illusions, offering insights for diverse applications in thermal display design. Recent advancements in the field have spurred a fresh perspective on thermal and pain perception, specifically through the lens of thermal illusions.

Mirror-Brush Illusion: Creating Phantom Tactile Percepts on Intact Limbs.

Haptic illusions provide unique insights into how we model our bodies separate from our environment. Popular illusions like the rubber-hand illusion and mirror-box illusion have demonstrated that we can adapt the internal representations of our limbs in response to visuo-haptic conflicts. In this manuscript, we extend this knowledge by investigating to what extent, if any, we also augment our external representations of the environment and its action on our bodies in response to visuo-haptic conflicts. Utilizing a mirror and a robotic brushstroking platform, we create a novel illusory paradigm that presents a visuo-haptic conflict using congruent and incongruent tactile stimuli applied to participants' fingers. Overall, we observed that participants perceived an illusory tactile sensation on their visually occluded finger when seeing a visual stimulus that was inconsistent with the actual tactile stimulus provided. We also found residual effects of the illusion after the conflict was removed. These findings highlight how our need to maintain a coherent internal representation of our body extends to our model of our environment.

A haptic illusion created by gravity

Human dexterity requires very fine and efficient control of fingertip forces, which relies on the integration of cutaneous and proprioceptive feedback. Here, we examined the influence of gravity on isometric force control. We trained participants to reproduce isometric vertical forces on a dynamometer held between the thumb and the index finger in normal gravity and tested them during parabolic flight creating phases of microgravity and hypergravity, thereby strongly influencing the motor commands and the proprioceptive feedback. We found that gravity creates the illusion that upward forces are larger than downward forces of the same magnitude. The illusion increased under hypergravity and was abolished under microgravity. Gravity also affected the control of the grip force employed to secure the grasp. These findings suggest that gravity biases the haptic estimation of forces, which has implications for the design of haptic devices to be used during flight or space activities.

Perceptual Localization Performance of the Whole Hand Vibrotactile Funneling Illusion.

Funneling illusion refers to a midway perceived illusory tactile sensation between multiple distant stimulations. Since haptic illusion provides guidelines to simplify tactile interfaces, funneling illusion has been explored on different parts of human skin. This study aimed to evaluate the perceptual localization performance of vibrotactile funneling illusion on palmar side of the hand. It is based on the idea of leveraging the vibrotactile funneling illusion to produce distributed vibrotactile stimuli across the entire hand using only a few vibration actuators. By designing a glove with actuators on five fingertips and the palm heel, we measured the localization density of funneling illusion on the whole hand in two experimental conditions [one-dimensional (1D) illusion along each finger and 2D illusion on palmar plane]. The results showed that the average correct rate of location discrimination was 97%, 82%, and 71% in 3-, 4-, and 5-location densities for 1D illusion and 85%, 70%, and 58% in 11-, 16-, and 21-location densities for 2D illusion, respectively. These findings confirmed the feasibility of simulating multi-location stimuli using only a few actuators. Also, perceptual guidelines were provided for the designing of vibrotactile gloves by leveraging the entire hand funneling illusion.

"I see where this is going": a psychophysical study of directional mid-air haptics and apparent tactile motion.

Mid-air haptic technology can render a plethora of tactile sensations including points, lines, shapes, and textures. To do so, one requires increasingly complex haptic displays. Meanwhile, tactile illusions have had widespread success in the development of contact and wearable haptic displays. In this article, we exploit the apparent tactile motion illusion to display mid-air haptic directional lines; a prerequisite for the rendering of shapes and icons. We present two pilot studies and a psychophysical study that contrasts a dynamic tactile pointer (DTP) to an apparent tactile pointer (ATP) in terms of direction recognition. To that end, we identify optimal duration and direction parameters for both DTP and ATP mid-air haptic lines and discuss the implications of our findings with respect to haptic feedback design, and device complexity.

The knobby ball illusion.

A novel haptic illusion is described where deformations of the fingertip skin lead to subsequent misperceptions of an object's shape.

Immediate effect of lower extremity joint manipulation on a lower extremity somatosensory illusion: a randomized, controlled crossover clinical pilot study.

Objective: This study explored the influence of lower extremity manipulation on the postural after-effects of standing on an inclined surface. Methods: Eight healthy individuals (28.0 ± 4.1 years) were recruited for this open-label, crossover study. Participants stood on an incline board for 3 min to develop a known form of somatosensory illusion. After randomization to either a lower-extremity joint manipulation or no intervention, participants immediately stood on a force plate for 3 min with eyes closed. After a 24-h washout period, participants completed the remaining condition. Center of pressure (CoP) position data was measured by a force plate and evaluated using statistical parametric mapping. Pathlength, mean velocity, and RMS were calculated for significant time periods and compared with corrected paired t-tests. Results: Parametric maps revealed that CoP position of control and intervention conditions differed significantly for two time periods (70-86 s-control: 0.17 ± 1.86 cm/intervention: -1.36 ± 1.54 cm; 141-177 s-control: -0.35 ± 1.61 cm/intervention: -1.93 ± 1.48 cm). CoP pathlength was also significantly decreased for the second period (control: 6.11 ± 4.81 cm/intervention: 3.62 ± 1.92 cm). Conclusion: These findings suggest that extremity manipulation may be a useful intervention for populations where CoP stability is an issue. This study contributes to the growing body of evidence that manipulation of the extremities can drive global postural changes, as well as influence standing behavior. Further, it suggests these global changes may be driven by alterations in central integration. Clinical Trial Registration: ClinicalTrials.gov, NCT Number: NCT05226715.

Comparative Experimental Research on Haptic Display Methods of Virtual Surface Shape Based on Touch Screen.

With the wide application of touch screen technology in daily life, more and more studies have tried to use touch screen as a carrier to convey the surface shape features of virtual objects to people. Current studies have proposed methods such as direct height mapping and haptic illusion based on lateral force to display the geometric shape of virtual surfaces on the touch screen. However, whether there are differences in the performance of these methods in displaying the shape features, and whether the lateral force-based haptic illusion can be used to display the shape features of complex surfaces, has not been fully explored. Aiming at this situation, in this article, we carry out user experiments on two regular shapes and eight natural images under displacement field and two types of lateral force fields with the help of three haptic devices previously designed. We also evaluate the effect of image smoothing on users' perception of natural image shape features. Experimental results show that the current shape display devices and methods that can simulate the lateral force field proposed by (Minsky et al., 1990) cannot achieve the display effect of the displacement field on complex shapes, and the shape display effect is the worst when only resistive lateral force feedback is employed. Nevertheless, since methods based on lateral force field, such as electrovibration, allow people to directly perceive the shape features of the virtual surface on the touch screen with their bare fingers, continuous research on this shape expression method still has a very attractive prospect.

Stress-, Anxiety-, and Cellphone use-induced Sleep Deficits and Psychological Conditions during the Pandemic and a Potential Remedy: a Randomized, Parallel, Blinded, Placebo-controlled Study

Healthier environments could prevent almost one quarter of the global burden of disease. The COVID-19 pandemic is a further reminder of the delicate relationship between people and our planet (WHO 2022). Since the appearance of the cell phone, the anomalous use of this device has called into question, as a new healthier environment issue, especially during this COVID-19 virus pandemic spreading, which may be linked to social isolation. This problem is identical to the one regarding the existence of behavioral addictions, including rigidity and muscle pain, ocular afflictions resulting from Computer Vision Syndrome reflected in fatigue, dryness, blurry vision, irritation, or ocular redness, auditory and tactile illusions – the sensation of having heard a ring or felt a vibration of a cell phone, and pain and weakness in the thumbs and wrists leading to an increased number of cases of de Quervain’s tenosynovitis. With respect to the psychological problems derived from cellphone dependence, the research focuses on the sub-consequence of cellphone dependence, sleep interference and its coexistence with using substances such as alcohol and tobacco and with symptomatology and psychiatric comorbidities, particularly anxiety, stress, and depression. In this study, authors surveyed 288 volunteers to gain insight regarding how stress, anxiety, and time spent on cellphones affected sleep and mood, and how a novel herb compound preparation, dihydromyricetin (DHM)-containing product improves these syndromes. The results clearly showed a negative linear correlation between sleep duration vs stress level and time on cellphone, and a negative correlation between wake-up mood/symptoms vs stress. Interestingly, volunteers taking DHM-containing product, but not placebo, showed substantial improvements in stress levels, hours of sleep, especially cellphone dependence, and wake-up mood/symptoms. This is a highly interesting study that addresses the current health problems, new healthier environment issue and suggests a potential therapeutic roles of DHM and/or herbs in behavioral addictions and associated mental health and wellbeing.

Pseudo-haptic button for improving user experience of mid-air interaction in VR

Mid-air interaction is one of the promising interaction modalities in virtual reality (VR) due to its merits in naturalness and intuitiveness, but the interaction suffers from the lack of haptic feedback as no force or vibrotactile feedback can be provided in mid-air without extra devices. As a breakthrough to compensate for this insufficiency, the application of pseudo-haptic features which create the visuo-haptic illusion without actual physical haptic stimulus can be explored. Therefore, this study aimed to investigate the effect of four pseudo-haptic features: proximity feedback, protrusion, hit effect, and penetration blocking on user experience for free-hand mid-air button interaction in VR. We conducted a user study on 21 subjects to collect user ratings on various aspects of user experience while users were freely interacting with 16 buttons with different combinations of four features. Results indicated that all investigated features significantly improved user experience in terms of haptic illusion, embodiment, sense of reality, spatiotemporal perception, satisfaction, and hedonic quality. In addition, protrusion and hit effect were more beneficial in comparison with the other two features. It is recommended to utilize the four proposed pseudo-haptic features in 3D user interfaces (UIs) to make users feel more pleased and amused, but caution is needed when using proximity feedback together with other features because it can be distracting. The findings of this study could be helpful for VR developers and UI designers in providing better interactive buttons in the 3D interfaces.

If I Feel It, I Desire It…: Harnessing Visual-induced Tactile Imagery for Enhancing Purchase Intention

How can marketers create an illusion of touch through expanding the roles of the visual sense to better present products on online shopping platforms? This study is a conceptual attempt to apply cross-modal mental imagery in the context of generating illusions of tactile sense through stimulating visual sense by the use of sensory-aided descriptions (SAD). We establish that these perceptual illusions can enhance the purchase intention of online shoppers when they are making purchases. Furthermore, we introduce that this linkage is moderated by the unique imaginative capability of the customer. The proposed model in this paper provides thoughtful insights for marketing managers to consider during the process of designing online product presentations. Theoretically, it contributes by establishing that cross-modal mental imagery, when applied over SAD, can serve as effective stimuli in the generation of tactile mental imagery.

Pseudo-haptics and self-haptics for freehand mid-air text entry in VR

Despite the lack of haptic feedback, two-finger typing remains as a common freehand mid-air text entry method in VR. To compensate for this limitation, we investigated the effect of pseudo-haptics and thumb-to-finger pinch self-haptics. Three types of virtual keyboards were developed for comparison: a normal virtual keyboard without any haptic features, a pseudo-haptic keyboard providing a haptic illusion by adding pseudo-haptic features to the normal virtual keyboard, and a pinch keyboard providing passive self-haptic feedback when the index finger touches the thumb to type bubble-shaped keys. A follow-up user study was conducted on the three keyboards to measure typing performance, perceived workload, and user experience. The results showed that the pseudo-haptic and pinch keyboards were comparable to the normal one in typing performance and workload, but beneficial in user experience and preference. The findings suggest that pseudo-haptics and self-haptics could achieve experiential benefits in VR text entry without obtrusive extra devices.

Haptic Devices: Wearability-Based Taxonomy and Literature Review

In the last decade, several new haptic devices have been developed, contributing to the definition of more realistic virtual environments. An overview on this topic requires a description of the various technologies employed in building such devices, and of their application domains. This survey describes the current technology underlying haptic devices, based on the concept of “wearability level”. More than 90 devices, newly developed and described in scientific papers published in the period 2010-2021, are reviewed, which provide either haptic illusions or novel haptic feedback for teleoperation, entertainment, training, education, guidance and notification. As a result, the analyzed systems are divided into grounded, hand-held and wearable devices; the latter are further split into exoskeletons and gloves, finger-worn devices, and arm-worn devices. For the systems in each of these categories, descriptions and tables are provided that analyze their structure, including device mass and employed actuators, their applications, and other characteristics such as type of haptic feedback and tactile illusions. The paper also provides an overview of devices worn in parts of the human body other than arms and hands, and precisely haptic vests, jackets and belts, and haptic devices for head, legs and feet. Based on this analysis, the survey also provides a discussion on research gaps and challenges, and potential future directions.

3D Filmmaking for User-Selective UHD Stereoscopic Media System: A Case Study on the Film The Old, the New and the Other

Despite skepticism about commercial potential, the stereoscopic 3D cinema is still a form that any filmmaker can choose to employ for its aesthetics and its immersive potential. Based on a haptic illusion, the stereoscopic media content requires a new perspective different from the principle of 2D media content in terms of creation and acceptance. This paper examines the technical and aesthetic issues of stereoscopic 3D film production from the perspective of today’s emerging realistic and immersive media through a case study. One of the key factors for successful content creation and research and development in stereoscopic 3D cinema is the combination of artistic principles together with technical mastering of the new image technology. The purpose of this paper is to outline the principal challenges and research topics in stereoscopic 3D cinema through a case study of stereoscopic 3D pilot film production for the ‘User-Selective UHD Stereoscopic Media Service Platform’ of the ETRI (Electronics and Telecommunications Research Institute). This paper intends to examine stereoscopic 3D filmmaking workflow and production methodologies, as well as technical elements and aesthetic issues.

Investigation of Tactile Illusion Based on Gestalt Theory

Time-evolving tactile sensations are important in communication between animals as well as humans. In recent years, this research area has been defined as “tactileology,” and various studies have been conducted. This study utilized the tactile Gestalt theory to investigate these sensations. Since humans recognize shapes with their visual sense and melodies with their auditory sense based on the Prägnanz principle in the Gestalt theory, this study assumed that a time-evolving texture sensation is induced by a tactile Gestalt. Therefore, the operation of such a tactile Gestalt was investigated. Two psychophysical experiments were conducted to clarify the operation of a tactile Gestalt using a tactile illusion phenomenon called the velvet hand illusion (VHI). It was confirmed that the VHI is induced in a tactile Gestalt when the laws of closure and common fate are satisfied. Furthermore, it was clarified that the tactile Gestalt could be formulated using the proposed factors, which included the laws of elasticity and translation, and it had the same properties as a visual Gestalt. For example, the strongest Gestalt factor had the highest priority among multiple competing factors.