This study was not funded.

The following protocol follows the guidelines of human research ethics committee of the university. See Table of Materials for reference to the commercial products.
NOTE: After receiving approval of the university ethics committee, 20 healthy individuals (7 males and 13 females, mean and standard deviation [SD] of age 30.2 &#177; 16.3 years) were recruited. Each subject read and signed an informed consent form pretrial. Inclusion criteria were right-handed individuals aged 18 or above. Exclusion criteria were any neurological or orthopaedic impairment affecting the upper extremities or uncorrected sight impairment. The subjects were na&#239;ve to the occurrences of incongruent visual-tactile feedback.
1. Pre-trial preparation
<ol>
	<li>Use the wooden box from the box and blocks test10. The dimensions of the box are 53.7 cm x 26.9 cm x 8.5 cm and in the middle of it, is a 15.2 cm high partition. Place a soft sponge layer on both sides of the partition. Place six passive reflective markers on the aspect opposite to the screen, at the four corners and on both ends of the partition (Figure 1a).</li>
	<li>Use a 3D-printer to manufacture a cube with the dimensions of 2.5 cm x 2.5 cm x 2.5 cm, attached to a base with the dimensions of 4.5 cm x 4.5 cm x 1 cm. Before printing, cut each corner of the base to create a square of size 1 cm x 1 cm at each corner (Figure 1a). Attach passive reflective markers on the four corners of the base.</li>
	<li>Place a large screen approximately 1.5 m in front of a table, so that a subject, standing behind the table, is approximately 2 m from the screen. Place the box on the table, 10 cm from the edge opposite to the screen.</li>
	<li>Use a 6-camera motion capture system, activated at 100 Hz, with a plug-in to visualize the partition and the movement of the block in real-time (Figure 1). Calibrate the motion capture system, according to the guidelines of the manufacturer, so that the block and partition of the box are recognized as rigid bodies. 
	NOTE: Proper calibration of the motion capture system and usage of small markers that are firmly attached to the block and partition are required to maintain the illusion.</li>
</ol>
2. Placing the vibrotactile feedback system on the subject
NOTE: The VTF system described herein was previously published11,12,13,14.
<ol>
	<li>Instruct the subject to remove wristwatch, bracelets and rings. Attach the VTF system controller to the forearm of the subject (Figure 2, left image).</li>
	<li>Attach two thin and flexible force sensors to the palmar aspect of the thumb and index fingers over a thin spongy layer (Figure 2, right image).</li>
	<li>Place a cuff on the skin of the upper arm of the subject (Figure 2, left image) and use the fastener to close the cuff comfortably. The cuff will contain three vibrotactile actuators activated via an open-source electronic prototyping platform at a frequency of 233 Hz in a linear relation to the force perceived by the force sensors. The force sensors and vibrotactile actuators are connected to the open-source electronic prototyping platform via shielded electric wires.</li>
</ol>
3. VTF activation
<ol>
	<li>Press the button to activate the battery attached to the controller (Figure 2, left image).</li>
	<li>Ask the subject to press the force sensor&#8217;s instrumented fingers (i.e., the thumb and index fingers) together lightly. Note that the subject will report a sense of vibration at the area under the cuff.</li>
	<li>Instruct the subject to train for 10 min in grasping the block as lightly as possible, using only the two instrumented fingers. Ask the subject to lift the block, move it, and place it back on the table several times, attempting to apply a minimal amount of force on the block. Encourage the subject to attempt to reduce the applied force, even if the block is dropped during grasping.</li>
</ol>
4. Positioning and preparing the subject
<ol>
	<li>Instruct the subject to stand close to the table (up to 10 cm from it), where the box and partition are placed.</li>
	<li>Place a divider at the edge of the table near the subject and above the box, so that the subject is unable to see the box but can easily see the screen in front of him or her (Figure 1a). For the divider, use a hard non-reflective material, preferably wood, fixed on a four legs, which permit the adjustment of their height, to accommodate subjects of different heights.</li>
	<li>Instruct the subject to place the earphones on his or her head.</li>
	<li>Place the block in the middle of the right compartment of the box and guide the hand of the subject to it.</li>
</ol>
5. Commencing trial
NOTE: The described trial is repeated twice, with and without the VTF (a cross-over design is recommended to verify a no learning effect). To perform the trial without the VTF, turn off the battery attached to the controller (Figure 2).
<ol>
	<li>Activate the software controlling the cameras of the motion capture system.</li>
	<li>In the control panel of the visual feedback software (Figure 1b), select with/without VTF, type the code of the subject, click Run, Connect, Open and Start.</li>
	<li>Instruct the subject to perform 16 repetitions of transferring the block with the force sensor&#8217;s instrumented hand while viewing the movement of the virtual block on the screen (Figure 1b). After each transfer, move the block back across the partition to its starting location.</li>
	<li>After the subject completed 16 repetitions, click Stop.</li>
	<li>Ask the subject to rate the difficulty level of performing the task of transferring the block 16 times twice, with and without the VTF, according to the following scale: &#8216;0&#8217; (not difficult at all), &#39;1&#39; (slightly difficult), &#39;2&#39; (moderately difficult), &#39;3&#39; (very difficult), and &#8216;4&#8217; (extremely difficult).</li>
</ol>
6. Post analysis
<ol>
	<li>Use the 3D coordinate data of the block the compute the path of the block and its transfer time. Mark the onset and offset time of each transfer manually as when the block is at the height of the rims of the right (onset) and then left (offset) sides of the box. Calculate the path length of each transfer according to the following equation: 
	(1) <img alt="Equation 1" src="/files/ftp_upload/59493/59493eq1.jpg" /> 
	where <img alt="Equation 2" src="/files/ftp_upload/59493/59493eq2.jpg" /> and <img alt="Equation 3" src="/files/ftp_upload/59493/59493eq3.jpg" /> are the 3D coordinate of the block in two subsequent time points.</li>
	<li>For both conditions, with and without VTF, average the path length and transfer time once for the two transfers with incongruent visual-tactile signals and once for the 14 transfers with the congruent visual-tactile signals.</li>
	<li>Normalized the path and time during block transfer in the presence of incongruent visual-tactile signals by the path and time during block transfer with the presence of congruent visual-tactile signals. Perform the normalization separately for the two conditions (with and without VTF).</li>
	<li>Perform a within-subject repeated-measures ANOVA with two factors: VTF (with and without) and incongruent visual-tactile feedback (with and without).</li>
	<li>If there are no statistical differences when analyzing the results following the instructions in subsection 6.4, use Bayesian repeated measures ANOVAs with two factors15.</li>
	<li>Use the Spearman&#8217;s correlation test with the perceived difficulty level of performing the task with the VTF activated and with the normalized path and duration of the motion</li>
	<li>Set the statistical significance to p &#60; .05.</li>
</ol>

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The authors have nothing to disclose.

In this study, a protocol that quantifies the effect of adding VTF on the object transfer kinematics in the presence of incongruent visual-tactile stimuli was presented. To the best of our knowledge, this is the only protocol available to test the effect of VTF on the response to incongruent visual-tactile stimuli. The several critical steps involved in the application of incongruent visual-tactile stimuli during object transfer with VTF include the following: attaching the VTF system to the subject, activating the VTF, ...

Illusions are exploitations of the limitations of our senses, as we mistakenly perceive information that deviates from objective reality. Our perceptual inference is based on our experience in interpreting sensory data and on the calculation of our brain of the most reliable estimate of reality in the presence of ambiguous sensory input1.
A sub-category in the research of illusions is one that combines incongruent sensory signals. The illusion that results from incongruent sensory signals originates from the constant multisensory integration performed by our brain. While there are numerous studies concerning incongruence in visual-auditory signals, incongruence in other sensory pairs is less reported. This difference in the number of reports might be attributed to the higher simplicity in designing a setup that incorporates visual-auditory incongruence. However, studies that report results relating to other sensory pairs modalities, are interesting. For example, the effect of incongruent visual-haptic signals on visual sensitivity2 was studied using a system where the visual and haptic stimuli were matched in spatial frequency; however, the haptic and visual orientation was identical (congruent) or orthogonal (incongruent). In another study, the effect of incongruent visual-tactile motion stimuli on the perceived visual direction of motion was investigated using a visual-tactile cross-modal integration stimulator with a lighted panel that presents visual stimuli and a tactile stimulator that presents tactile motion stimuli with arbitrary motion direction, speed, and indentation depth in the skin3. It was suggested that we internally represent both the statistical distribution of the task and our sensory uncertainty, combining them in a manner consistent with a performance-optimizing Bayesian process4.
Virtual reality has made the ability to deceive the visual feedback to the subject an easy task. Several studies used multisensory virtual reality to misalign visual and somatosensory information. For example, virtual reality was recently used to induce embodiment in a child&#8217;s body, with or without activation of a child-like voice distortion5. In another example, the visual presentation of the walking distance during self-motion was extended and was therefore incongruent with the travel distance felt by body-based cues6. A similar virtual reality setup was designed for a cycling activity7. All of the aforementioned literature, however, did not combine an interference to one of the senses, in addition to the incongruent signal. We chose the tactile sense to receive such a disturbance.
Our tactile sensory system provides direct evidence as to whether an object is being grasped. We therefore expect that when direct visual feedback is distorted or unavailable, the role of the tactile sensory system in object manipulation tasks will be prominent. However, what would happen if the tactile sensory channel was also disturbed? This is a possible outcome of using vibrotactile feedback (VTF) for sensory augmentation, as it captures the attention of the individual8. Today, augmented feedback of different modalities is used as an external tool, meant to enhance our internal sensory feedback and improve performance during motor learning, in sport and in rehabilitation settings9.
The study of incongruent visual-tactile stimuli may enhance our understanding regarding perception of the sensory input. Particularly, quantification of the additive or reductive value of VTF during motor function that involves incongruent visual-tactile stimuli, can assist in future prosthetics design, smart sport-wear, or any other garments that incorporate VTF. Since amputees are deprived of tactile stimuli at the distal aspect of their residuum, their daily usage of the VTF, embedded in the prosthetic to convey knowledge of grasping, for example, might influence how they perceive visual feedback. Understanding of the mechanism of perception under these conditions, will allow engineers to perfect VTF modalities to reduce the negative effect on VTF users.
We aimed to test the effect of VTF on the response to incongruent visual-tactile stimuli. In the presented setup, the tactile feedback is acquired by grasping a block and moving it across a partition; the visual feedback is a real-time virtual presentation of the moving block and the partition (acquired using a motion capture system). Since the subject is prevented from seeing the actual hand movement, the only visual feedback is the virtual one. The congruent feedback is the reliable presentation of the movement of the block, so that the subject feels that the block is grasped and sees it move along with the path of the hand. The incongruent feedback appears as the movement of the block diverts from the actual movement path, so that it seems to drop from the hand when it is actually still held by the subject, thereby contradicting the tactile feedback. Three hypotheses were tested: when moving an object from one place to another using virtual visual feedback, (i) the path and duration of the object&#8217;s transfer motion will increase when incongruent visual-tactile stimuli is presented, (ii) this change will increase when incongruent visual-tactile stimuli is presented and VTF is activated on the moving arm, and (iii) a positive correlation will be found between the perceived difficulty level of performing the task with the VTF activated and the path and duration of the object&#8217;s transfer motion. The first hypothesis originates from aforementioned literature that report that various modalities of incongruent feedback affect our responses. The second hypothesis relates to the previous findings that VTF captures the attention of the individual. For the third hypothesis, we assumed that subjects who were more disturbed by the VTF, will trust the virtual visual feedback more than their tactile sense.

<table><tbody><tr><td>3D printer</td><td>Makerbot</td><td></td><td>https://www.makerbot.com/</td></tr><tr><td>Box and Blocks test</td><td>Sammons Preston</td><td></td><td>https://www.performancehealth.com/box-and-blocks-test</td></tr><tr><td>Flexiforce sensors (1lb)</td><td>Tekscan Inc.</td><td></td><td>https://www.tekscan.com/force-sensors</td></tr><tr><td>JASP</td><td>JASP Team</td><td></td><td>https://jasp-stats.org/</td></tr><tr><td>Labview</td><td>National Instruments</td><td></td><td>http://www.ni.com/en-us/shop/labview/labview-details.html</td></tr><tr><td>Micro Arduino</td><td>Arduino LLC</td><td></td><td>https://store.arduino.cc/arduino-micro</td></tr><tr><td>Motion capture system</td><td>Qualisys</td><td></td><td>https://www.qualisys.com</td></tr><tr><td>Shaftless vibration motor</td><td>Pololu</td><td></td><td>https://www.pololu.com/product/1638</td></tr><tr><td>SPSS</td><td>IBM</td><td></td><td>https://www.ibm.com/analytics/spss-statistics-software</td></tr></tbody></table>

applying incongruent visual-tactile stimuli during object transfer with vibro-tactile feedback

The application of incongruent sensory signals that involves disrupted tactile feedback is rarely explored, specifically with the presence of vibrotactile feedback (VTF). This protocol aims to test the effect of VTF on the response to incongruent visual-tactile stimuli. The tactile feedback is acquired by grasping a block and moving it across a partition. The visual feedback is a real-time virtual presentation of the moving block, acquired using a motion capture system. The congruent feedback is the reliable presentation of the movement of the block, so that the subject feels that the block is grasped and see it move along with the path of the hand. The incongruent feedback appears as the movement of the block diverts from the actual movement path, so that it seems to drop from the hand when it is actually still held by the subject, thereby contradicting the tactile feedback. Twenty subjects (age 30.2 &#177; 16.3) repeated 16 block transfers, while their hand was hidden. These were repeated with VTF and without VTF (total of 32 block transfers). Incongruent stimuli were presented randomly twice within the 16 repetitions in each condition (with and without VTF). Each subject was asked to rate the difficulty level of performing the task with and without the VTF. There were no statistically significant differences in the length of the hand paths and durations between transfers recorded with congruent and incongruent visual-tactile signals &#8211; with and without the VTF. The perceived difficulty level of performing the task with the VTF significantly correlated with the normalized path length of the block with VTF (r = 0.675, p = 0.002). This setup is used to quantify the additive or reductive value of VTF during motor function that involves incongruent visual-tactile stimuli. Possible applications are prosthetics design, smart sport-wear, or any other garments that incorporate VTF.

We used the described technique to test the three hypotheses that when moving an object from one place to another using virtual visual feedback: (i) the path and duration of the object&#8217;s transfer motion will increase when incongruent visual-tactile stimuli is presented; (ii) this change will increase when incongruent visual-tactile stimuli is presented and VTF is activated on the moving arm; and (iii) a positive correlation will be found between the perceived difficulty level of performing the task with the VTF act...

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Applying Incongruent Visual-Tactile Stimuli during Object Transfer with Vibro-Tactile Feedback

We present a protocol to apply incongruent visual-tactile stimuli during an object transfer task. Specifically, during block transfers, performed while the hand is hidden, a virtual presentation of the block shows random occurrences of false block drops. The protocol also describes adding vibrotactile feedback while performing the motor task.

The application of incongruent sensory signals that involves disrupted tactile feedback is rarely explored, specifically with the presence of vibrotactile ...

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5.4K Views.  Tel Aviv University. Het protocol test het effect van vibro-tactiele feedback op de reactie op incongruente visueel tactiele stimuli. Een bewegingsafvangsysteem berekent de 3D-coördinaten van een blok dat over een partitie wordt overgebracht. Dus de analyse van de bewegingstijd en het pad van het blok in elke herhaling kan efficiënt en nauwkeurig worden uitgevoerd aan het einde van het proces.De reactie van het onderwerp op de incongruente visueel-tactiele stimuli in aanwezigheid van vibro-tactiele feedb...

Video: Applying Incongruent Visual-Tactile Stimuli during Object Transfer with Vibro-Tactile Feedback

The Crossmodal Congruency Task as a Means to Obtain an Objective Behavioral Measure in the Rubber Hand Illusion Paradigm

The rubber hand illusion (RHI) is a popular experimental paradigm. Participants view touch on an artificial rubber hand while the participants' own hidden hand is touched. If the viewed and felt touches are given at the same time then this is sufficient to induce the compelling experience that the rubber hand is one's own hand. The RHI can be used to investigate exactly how the brain constructs distinct body representations for one's own body. Such representations are crucial for successful interactions with the external world. To obtain a subjective measure of the RHI, researchers typically ask participants to rate statements such as "I felt as if the rubber hand were my hand". Here we demonstrate how the crossmodal congruency task can be used to obtain an objective behavioral measure within this paradigm.
The variant of the crossmodal congruency task we employ involves the presentation of tactile targets and visual distractors. Targets and distractors are spatially congruent (i.e. same finger) on some trials and incongruent (i.e. different finger) on others. The difference in performance between incongruent and congruent trials - the crossmodal congruency effect (CCE) - indexes multisensory interactions. Importantly, the CCE is modulated both by viewing a hand as well as the synchrony of viewed and felt touch which are both crucial factors for the RHI.
The use of the crossmodal congruency task within the RHI paradigm has several advantages. It is a simple behavioral measure which can be repeated many times and which can be obtained during the illusion while participants view the artificial hand. Furthermore, this measure is not susceptible to observer and experimenter biases. The combination of the RHI paradigm with the crossmodal congruency task allows in particular for the investigation of multisensory processes which are critical for modulations of body representations as in the RHI.

We demonstrate how an objective measure can be employed in the widely employed rubber hand illusion paradigm. This measure is obtained by modifying the well-established crossmodal congruency task. This task allows the investigation of multisensory processes which are critical for modulations of body representations as in the rubber hand illusion.

The rubber hand illusion (RHI) is a popular experimental paradigm. Participants view touch on an artificial rubber hand while the participants' own hidden ...

Quantitative Assessment of Cortical Auditory-tactile Processing in Children with Disabilities

Objective and easy measurement of sensory processing is extremely difficult in nonverbal or vulnerable pediatric patients. We developed a new methodology to quantitatively assess children&#39;s cortical processing of light touch, speech sounds and the multisensory processing of the 2 stimuli, without requiring active subject participation or causing children discomfort. To accomplish this we developed a dual channel, time and strength calibrated air puff stimulator that allows both tactile stimulation and sham control. We combined this with the use of event-related potential methodology to allow for high temporal resolution of signals from the primary and secondary somatosensory cortices as well as higher order processing. This methodology also allowed us to measure a multisensory response to auditory-tactile stimulation.

Objective and easy measurement of sensory processing is extremely difficult in nonverbal or vulnerable pediatric patients. We developed a new methodology to quantitatively assess infants and children&#39;s cortical processing of light touch, speech sounds, and the multisensory processing of the 2 stimuli, without requiring active subject participation or causing discomfort in vulnerable patients.

Objective and easy measurement of sensory processing is extremely difficult in nonverbal or vulnerable pediatric patients. We developed a new methodology ...

Haptic/Graphic Rehabilitation: Integrating a Robot into a Virtual Environment Library and Applying it to Stroke Therapy

Recent research that tests interactive devices for prolonged therapy practice has revealed new prospects for robotics combined with graphical and other forms of biofeedback. Previous human-robot interactive systems have required different software commands to be implemented for each robot leading to unnecessary developmental overhead time each time a new system becomes available. For example, when a haptic/graphic virtual reality environment has been coded for one specific robot to provide haptic feedback, that specific robot would not be able to be traded for another robot without recoding the program. However, recent efforts in the open source community have proposed a wrapper class approach that can elicit nearly identical responses regardless of the robot used. The result can lead researchers across the globe to perform similar experiments using shared code. Therefore modular "switching out"of one robot for another would not affect development time. In this paper, we outline the successful creation and implementation of a wrapper class for one robot into the open-source H3DAPI, which integrates the software commands most commonly used by all robots.

Recently, a vast amount of prospects have come available for human-robot interactive systems. In this paper we outline the integration of a new robotic device with open source software that can rapidly make possible a library of interactive functionality. We then outline a clinical application for a neurorehabilitation application.

Recent research that tests interactive devices for prolonged therapy practice has revealed new prospects for robotics combined with graphical and other ...

Bioengineering

Measurement of Vibration Detection Threshold and Tactile Spatial Acuity in Human Subjects

Tests that allow the precise determination of psychophysical thresholds for vibration and grating orientation provide valuable information about mechanosensory function that are relevant for clinical diagnosis as well as for basic research. Here, we describe two psychophysical tests designed to determine the vibration detection threshold (automated system) and tactile spatial acuity (handheld device). Both procedures implement a two-interval forced-choice and a transformed-rule up and down experimental paradigm. These tests have been used to obtain mechanosensory profiles for individuals from distinct human cohorts such as twins or people with sensorineural deafness.

Here, we present protocols to determine vibration detection thresholds and tactile acuity using psychophysical methods in man.

Tests that allow the precise determination of psychophysical thresholds for vibration and grating orientation provide valuable information about ...

Visualization Method for Proprioceptive Drift on a 2D Plane Using Support Vector Machine

Proprioceptive drift, which is a perceptual shift in body-part position from the unseen real body to a visible body-like image, has been measured as the behavioral correlate for the sense of ownership. Previously, the estimation of proprioceptive drift was limited to one spatial dimension, such as height, width, or depth. As the hand can move freely in 3D, measuring proprioceptive drift in only one dimension is not sufficient for the estimation of the drift in real life situations. In this article, we provide a novel method to estimate proprioceptive drift on a 2D plane using the mirror illusion by combining an objective behavioral measurement (hand position tracking) and subjective, phenomenological assessment (subjective assessment of hand position and questionnaire) with a sophisticated machine learning approach. This technique permits not only an investigation of the underlying mechanisms of the sense of ownership and agency but also assists in the rehabilitation of a missing or paralyzed limb and in the design rules of real-time control systems with a self-body-like usability, in which the operator controls the system as if it were part of his/her own body.

This article describes a novel method to estimate proprioceptive drift on a 2D plane using the mirror illusion and combining a psychophysical procedure with an analysis using machine learning.

Proprioceptive drift, which is a perceptual shift in body-part position from the unseen real body to a visible body-like image, has been measured as the ...

Creating Virtual-hand and Virtual-face Illusions to Investigate Self-representation

Studies investigating how people represent themselves and their own body often use variants of &#34;ownership illusions&#34;, such as the traditional rubber-hand illusion or the more recently discovered enfacement illusion. However, these examples require rather artificial experimental setups, in which the artificial effector needs to be stroked in synchrony with the participants&#39; real hand or face&#8212;a situation in which participants have no control over the stroking or the movements of their real or artificial effector. Here, we describe a technique to establish ownership illusions in a setup that is more realistic, more intuitive, and of presumably higher ecological validity. It allows creating the virtual-hand illusion by having participants control the movements of a virtual hand presented on a screen or in virtual space in front of them. If the virtual hand moves in synchrony with the participants&#39; own real hand, they tend to perceive the virtual hand as part of their own body. The technique also creates the virtual-face illusion by having participants control the movements of a virtual face in front of them, again with the effect that they tend to perceive the face as their own if it moves in synchrony with their real face. Studying the circumstances that illusions of this sort can be created, increased, or reduced provides important information about how people create and maintain representations of themselves.

Here, we describe virtual-hand and virtual-face illusion paradigms that can be used to study body-related self-perception/-representation. They have already been used in various studies to demonstrate that, under specific conditions, a virtual hand or face can be incorporated into one&#39;s body representation, suggesting that body representations are rather flexible.

Studies investigating how people represent themselves and their own body often use variants of &#34;ownership illusions&#34;, such as the traditional ...

Using Virtual Reality to Transfer Motor Skill Knowledge from One Hand to Another

As far as acquiring motor skills is concerned, training by voluntary physical movement is superior to all other forms of training (e.g. training by observation or passive movement of trainee&#39;s hands by a robotic device). This obviously presents a major challenge in the rehabilitation of a paretic limb since voluntary control of physical movement is limited. Here, we describe a novel training scheme we have developed that has the potential to circumvent this major challenge. We exploited the voluntary control of one hand and provided real-time movement-based manipulated sensory feedback as if the other hand is moving. Visual manipulation through virtual reality (VR) was combined with a device that yokes left-hand fingers to passively follow right-hand voluntary finger movements. In healthy subjects, we demonstrate enhanced within-session performance gains of a limb in the absence of voluntary physical training. Results in healthy subjects suggest that training with the unique VR setup might also be beneficial for patients with upper limb hemiparesis by exploiting the voluntary control of their healthy hand to improve rehabilitation of their affected hand.

We describe a novel virtual-reality based setup which exploits voluntary control of one hand to improve motor-skill performance in the other (non-trained) hand. This is achieved by providing real-time movement-based sensory feedback as if the non-trained hand is moving. This new approach may be used to enhance rehabilitation of patients with unilateral hemiparesis.

As far as acquiring motor skills is concerned, training by voluntary physical movement is superior to all other forms of training (e.g. training by ...

A Vibrotactile Feedback Device for Seated Balance Assessment and Training

Postural perturbations, motion tracking, and sensory feedback are modern techniques used to challenge, assess, and train upright sitting, respectively. The goal of the developed protocol is to construct and operate a sitting platform that can be passively destabilized while an inertial measurement unit quantifies its motion and vibrating elements deliver tactile feedback to the user. Interchangeable seat attachments alter the stability level of the device to safely challenge sitting balance. A built-in microcontroller allows fine-tuning of the feedback parameters to augment sensory function. Posturographic measures, typical of balance assessment protocols, summarize the motion signals acquired during timed balance trials. No dynamic sitting protocol to date provides variable challenge, quantification, and sensory feedback free of laboratory constraints. Our results demonstrate that non-disabled users of the device exhibit significant changes in posturographic measures when balance difficulty is altered or vibrational feedback provided. The portable, versatile device has potential applications in rehabilitation (following skeletal, muscular, or neurological injury), training (for sports or spatial awareness), entertainment (via virtual or augmented reality), and research (of sitting-related disorders).

A sitting platform has been developed and assembled that passively destabilizes sitting posture in humans. During the user&#39;s stabilizing task, an inertial measurement unit records the device&#39;s motion, and vibrating elements deliver performance-based feedback to the seat. The portable, versatile device may be used in rehabilitation, assessment, and training paradigms.

Postural perturbations, motion tracking, and sensory feedback are modern techniques used to challenge, assess, and train upright sitting, respectively. ...

A Tactile Automated Passive-Finger Stimulator (TAPS)

Although tactile spatial acuity tests are used in both neuroscience research and clinical assessment, few automated devices exist for delivering controlled spatially structured stimuli to the skin. Consequently, investigators often apply tactile stimuli manually. Manual stimulus application is time consuming, requires great care and concentration on the part of the investigator, and leaves many stimulus parameters uncontrolled. We describe here a computer-controlled tactile stimulus system, the Tactile Automated Passive-finger Stimulator (TAPS), that applies spatially structured stimuli to the skin, controlling for onset velocity, contact force, and contact duration. TAPS is a versatile, programmable system, capable of efficiently conducting a variety of psychophysical procedures. We describe the components of TAPS, and show how TAPS is used to administer a two-interval forced-choice tactile grating orientation test.
Corresponding Author: Daniel Goldreich

A Tactile Automated Passive-Finger Stimulator TAPS

We describe a computer-controlled device for investigating the sense of touch: the Tactile Automated Passive-finger Stimulator (TAPS). We describe the components of TAPS, and show how TAPS is used to administer a two-interval forced-choice tactile grating orientation test.

Although tactile spatial acuity tests are used in both neuroscience research and clinical assessment, few automated devices exist for delivering ...

Biology

A Method for Evaluating Timeliness and Accuracy of Volitional Motor Responses to Vibrotactile Stimuli

Artificial sensory feedback (ASF) systems can be used to compensate for lost proprioception in individuals with lower-limb impairments. Effective design of these ASF systems requires an in-depth understanding of how the parameters of specific feedback mechanism affect user perception and reaction to stimuli. This article presents a method for applying vibrotactile stimuli to human participants and measuring their response. Rotating mass vibratory motors are placed at pre-defined locations on the participant's thigh, and controlled through custom hardware and software. The speed and accuracy of participants' volitional responses to vibrotactile stimuli are measured for researcher-specified combinations of motor placement and vibration frequency. While the protocol described here uses push-buttons to collect a simple binary response to the vibrotactile stimuli, the technique can be extended to other response mechanisms using inertial measurement units or pressure sensors to measure joint angle and weight bearing ratios, respectively. Similarly, the application of vibrotactile stimuli can be explored for body segments other than the thigh.

This article describes a technique for applying vibrotactile stimuli to the thigh of a human participant, and measuring the accuracy and reaction time of the participant&#39;s volitional response for various combinations of stimulation location and frequency.

Artificial sensory feedback (ASF) systems can be used to compensate for lost proprioception in individuals with lower-limb impairments.  Effective design ...

Applying Incongruent Visual-Tactile Stimuli during Object Transfer with Vibro-Tactile Feedback

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