We acknowledge all the participants, volunteers, and others involved in the study. We are grateful to Sandra Stolzenbach W&#230;hrens and Wender Bredie (University of Copenhagen) for designing the squares used in the present gratings orientation test. This research was funded by the University of Milan, Piano di sostegno alla ricerca 2018.

An informed, written consent has been signed by all participants. This study was approved by the Ethics Committee of the University of Milan (n. 48/19) and conducted in accordance with the Declaration of Helsinki.
1. Training of experimenters
<ol>
	<li>Take the grating tool and apply a force of 100 g on a sponge placed on a scale. 
	NOTE: Refer to Figure 1 for the schematic of the grating tool used in this study</li>
	<li>Repeat this procedure at least 10 times to reduce variation in the force applied by the grating on the subjects&#39; tongues during testing, both within and across experimenters.</li>
</ol>
2. Assessment procedure
NOTE: Conduct the assessment of tactile acuity following the required health and safety standard to guarantee the subject&#39;s safety (e.g., mask, gloves, and lab coat).
<ol>
	<li>Display all gratings (0.20 mm, 0.25 mm, 0.50 mm, 0.75 mm, 1.00 mm, 1.25 mm) (Figure 2) on a table out of sight of the participant.</li>
	<li>Seat the participant in a comfortable chair and inform them that they can leave the experiment at any time.</li>
	<li>Inform the participant that they will be blindfolded during the experiment and asked to stick out their tongue in a comfortable and relaxed way.</li>
	<li>Prior to the beginning of the experiment, familiarize the subjects with the procedure using the largest grating (1.25 mm) to demonstrate the force applied (100 g for 3 s).</li>
	<li>Notify the participants that they can take a sip of water whenever deemed appropriate.</li>
	<li>Apply each grating onto the subjects&#39; tongue (anterior region of the tongue just around the midline).</li>
	<li>After each touch, ask the subjects to indicate, using their hands, the tool&#39;s orientation (either horizontal or vertical) and their degree of sureness (sure, unsure). Subjects must guess if they do not know.</li>
	<li>After each touch, record all the answers (horizontal, vertical, sure, not sure) for each subject on a spreadsheet (Supplemental Table 1).</li>
	<li>Repeat each grating as many times as deemed necessary for the R-Index cut-off selected, for instance, 6 times, 3 horizontally, and 3 vertically (Supplemental Table 1).</li>
	<li>Sterilize each grating after testing each participant (refer to section 4). 
	NOTE: The tongue should protrude gently from the mouth without effort by the volunteers to avoid excessive fatigue, which would lead to an alteration in their performance results. It is important to note that the higher the repetitions by grating, the more reliable the measurement16.</li>
</ol>
3. Cleaning protocol
<ol>
	<li>Prepare a solution consisting of 20 mL of sodium hypochlorite (see Table of Materials) diluted in 1 L of water according to the manufacturer&#39;s instructions.</li>
	<li>Manually shake the solution for a few seconds.</li>
	<li>Fill 6 cups with approximately 20 mL of the disinfectant solution to fully immerse each tool in the solution.</li>
	<li>Place each tool in the corresponding cup.</li>
	<li>Let the tools soak for 15-20 min.</li>
	<li>Rinse the tools with plenty of water according to the manufacturer&#39;s instructions and scrub them with a toothbrush to ensure removing any sodium hypochlorite residue.</li>
	<li>Allow the tools to air dry.</li>
</ol>
4. R-index calculation
<ol>
	<li>Create a response matrix for each volunteer and for all the tools (Figure 3) based on the response frequencies used to calculate the R-index using the following equation: 
	<img alt="Equation 1" src="/files/ftp_upload/62898/62898eq01.jpg" /> 
	NOTE: R-index expresses individual tactile sensitivity for each tool16. R- index is based on SDT17 and represents an estimated probability of discerning a target stimulus (i.e., the signal) from an alternative stimulus (i.e., the noise). The signal and the noise correspond to the correct or incorrect identification of the horizontal-vertical orientation of the grating. Four response options for both signal and noise can occur: &#34;horizontal-sure&#34;, &#34;horizontal-unsure&#34;, &#34;vertical-unsure&#34; and &#34;vertical-sure&#34;16. R-index values range between 0-1. A higher R-index value indicates better discrimination.</li>
</ol>
5. Sensitivity and threshold determination by the R-index estimates
<ol>
	<li>To determine whether a subject can discriminate the orientation of each tool, calculate the cut-off using a table of critical values for R-index significance tests18 
	NOTE: Considering the present example, corresponding to 36 presentations (i.e., each grating presented 6 times, 3 horizontal and 3 vertical), the cut-off value for discrimination is set to 0.7426 according to the one-sided R-index critical values for &#945; = 0.0518.</li>
	<li>If a sufficiently high number of tools is used (e.g., six different grating dimensions)19, derive R-index threshold estimations.</li>
	<li>To calculate the threshold for each subject, interpolate the two R-indices immediately below and above of the cut-off value20.</li>
</ol>

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M., Klein, B. P., Lee, S. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Utilizing+the+R-index+measure+for+threshold+testing+in+model+caffeine+solutions.">Utilizing the R-index measure for threshold testing in model caffeine solutions.</a> Food Quality and Preference. 16 (4), 283-289 (2005).</li><li>Appiani, M., Rabitti, N. S., Methven, L., Cattaneo, C., Laureati, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assessment+of+lingual+tactile+sensitivity+in+children+and+adults:+Methodological+suitability+and+challenges.">Assessment of lingual tactile sensitivity in children and adults: Methodological suitability and challenges.</a> Foods. 9 (11), 1594 (2020).</li><li>Cattaneo, C., Liu, J., Bech, A. C., Pagliarini, E., Bredie, W. 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The authors have nothing to disclose.

Few valid instruments are available for measuring tactile acuity10,11,13,22. Von Frey filaments have been shown to be an adequate method for measuring both skin and oral tactile acuity10,21,22. However, these instruments measure a different dimension of lingual tactile acuity than the gratings orientat...

The texture and mouthfeel of food play an important role in liking1,2,3,4, and while research has found differences in texture perception due to factors such as chewing behavior2,5,&#160;saliva flow, and composition6,7, there are limited methods available to assess variation in oral tactile receptors (mechanoreceptors). The oral cavity houses different types of mechanoreceptors found in the mouth: Merkel receptors, Ruffini cylinders, and Meissner corpuscles8. Mechanoreceptors can be classed into two groups: slowly adapting and rapidly adapting. Slowly adapting mechanoreceptors (Ruffini cylinders and Merkel receptors) produce signals continuously while being stimulated. In contrast, rapidly adapting mechanoreceptors (Meissner&#39;s corpuscles) respond to the beginning and end of stimulation with a signal. Tactile acuity varies widely across tongue surfaces and between individuals, possibly due to differences in mechanoreceptor sensitivity. The location and the number of mechanoreceptors in the oral cavity, the differences in the spatial arrangement/density of the mechanoreceptors (spatial acuity), or the differences in their sensitivity when activated could be the cause of this intra- and inter-individual variability. Several methods to evaluate and screen for variation in mechanoreceptor sensitivity in the oral cavity have been published, including von Frey filaments9,10, letter recognition11,12, grating orientation tests13, and flexible electrode array14,15. The gratings orientation test requires square gratings (Figure 1, Figure 2) with different groove widths to be placed on the tongue of a blindfolded subject. They indicate if subjects perceive the gratings to be in either a horizontal or vertical orientation. Responses are used to calculate average thresholds based on the subject&#39;s ability to discriminate the orientation for the different grating sizes.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Custom-made squares</td>
			<td>University of Reading; University of Copenhagen</td>
			<td></td>
			<td>Squares of 1 cm2 from polytetrafluoroethylene (PTFE)</td>
		</tr>
		<tr>
			<td>Disinfenctant solution (20% sodium hypochlorite)</td>
			<td>Amuchina, Angelini S.p.A., Roma, Italy</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Eye masks</td>
			<td>Various</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Gloves</td>
			<td>Various</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Lab coat</td>
			<td>Various</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Plastic cup for drinking water</td>
			<td>Various</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Excel</td>
			<td>Microsoft</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

assessment of spatial lingual tactile sensitivity using a gratings orientation test

Individual thresholds by R-index estimates are calculated using a gratings orientation test (6 different tools of increasing grating size from 0.20-1.25 mm) to assess spatial lingual tactile sensitivity. During the experiment, the subjects are blindfolded and asked to specify the orientation of the grating (either horizontal or vertical) placed on the tongue. R-index is based on Signal Detection Theory (SDT), and it is an estimated probability of correctly identifying a target stimulus (the signal, e.g., the correct orientation) compared to an alternative stimulus (the noise, e.g., the incorrect orientation). Once the R-index values for each subject and each tool dimension are calculated, it is possible to derive the individual threshold by interpolating the two R-indices immediately below and above the established cut-off (typically 75%) based on one-sided R-index critical values. This procedure can be helpful in the medical field to study the association between oral tactile sensitivity, speech clarity, and swallowing disorders, as well as in sensory and consumer studies to explore individual variation in texture perception, food preferences, and eating behavior.

A total of 70 healthy adults (age range = 19-33 years; mean age = 22.0; 52.9% women) were involved in the study, as shown in Appiani et al. (2020)21.
As an example, the R-index distribution by age for square 0.75 mm is reported in Figure 4. Each point represents a different subject. Subjects above the dotted line (cut-off value: 0.7426) are those who correctly identify the orientation of the grating (more sensitive).
<p class="jove_cont...

Watch this Scientific Journal Video about Assessment of Spatial Lingual Tactile Sensitivity using a Gratings Orientation Test at JoVE.com

Assessment of Spatial Lingual Tactile Sensitivity using a Gratings Orientation Test

This work illustrates a standard procedure and threshold determination by the R-index to assess spatial lingual tactile sensitivity using a gratings orientation test.

Individual thresholds by R-index estimates are calculated using a gratings orientation test (6 different tools of increasing grating size from 0.20-1.25 ...

assessment-spatial-lingual-tactile-sensitivity-using-gratings

Universidad de Cartagena UDEC

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JoVE Journal

Behavior

2.5K Views.  University of Milan. This work illustrates a standard procedure and threshold determination by the R-index to assess spatial lingual tactile sensitivity using a gratings orientation test. 

Video: Assessment of Spatial Lingual Tactile Sensitivity using a Gratings Orientation Test

Measuring Sensitivity to Viewpoint Change with and without Stereoscopic Cues

The speed and accuracy of object recognition is compromised by a change in viewpoint; demonstrating that human observers are sensitive to this transformation. Here we discuss a novel method for simulating the appearance of an object that has undergone a rotation-in-depth, and include an exposition of the differences between perspective and orthographic projections. Next we describe a method by which human sensitivity to rotation-in-depth can be measured. Finally we discuss an apparatus for creating a vivid percept of a 3-dimensional rotation-in-depth; the Wheatstone Eight Mirror Stereoscope. By doing so, we reveal a means by which to evaluate the role of stereoscopic cues in the discrimination of viewpoint rotated shapes and objects.

We discuss a novel method forviewpoint-rotation of visual stimuli, and demonstrate using a mirror stereoscopethe three-dimensional percept of rotation-in-depth. The technique can be used to investigate the role of stereoscopic cues in encoding viewpoint-rotated figures.

The speed and accuracy of object recognition is compromised by a change in viewpoint; demonstrating that human observers are sensitive to this ...

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 ...

Experimental Assessment of Mouse Sociability Using an Automated Image Processing Approach

Mouse is the preferred model organism for testing drugs designed to increase sociability. We present a method to quantify mouse sociability in which the test mouse is placed in a standardized apparatus and relevant behaviors are assessed in three different sessions (called session I, II, and III).
The apparatus has three compartments (see Figure 1), the left and right compartments contain an inverted cup which can house a mouse (called &#34;stimulus mouse&#34;).
In session I, the test mouse is placed in the cage and its mobility is characterized by the number of transitions made between compartments. In session II, a stimulus mouse is placed under one of the inverted cups and the sociability of the test mouse is quantified by the amounts of time it spends near the cup containing the enclosed stimulus mouse vs. the empty inverted cup. In session III, the inverted cups are removed and both mice interact freely. The sociability of the test mouse in session III is quantified by the number of social approaches it makes toward the stimulus mouse and by the number of times it avoids a social approach by the stimulus mouse.
The automated evaluation of the movie detects the nose of the test mouse, which allows the determination of all described sociability measures in session I and II (in session III, approaches are identified automatically but classified manually). To find the nose, the image of an empty cage is digitally subtracted from each frame of the movie and the resulting image is binarized to identify the mouse pixels. The mouse tail is automatically removed and the two most distant points of the remaining mouse are determined; these are close to nose and base of tail. By analyzing the motion of the mouse and using continuity arguments, the nose is identified.
<img alt="Figure 1" src="/files/ftp_upload/52508/52508fig1.jpg" /> 
Figure 1. Assessment of Sociability During 3 sessions. Session I (top): Acclimation of test mouse to the cage. Session II (middle): Test mouse moving freely in the cage while the stimulus mouse is enclosed in an inverted cup. Session III (bottom): Both test mouse and stimulus mouse are allowed to move freely and interact with each other.

This protocol describes a method to quantify mouse sociability. Mice are videotaped as they move and interact in a special cage. Movie processing allows for the automated quantification of sociability with excellent accuracy and reliability.

Mouse is the preferred model organism for testing drugs designed to increase sociability. We present a method to quantify mouse sociability in which the ...

Assessment of Social Cognition in Non-human Primates Using a Network of Computerized Automated Learning Device (ALDM) Test Systems

Fagot &#38; Paleressompoulle1 and Fagot &#38; Bonte2 have published an automated learning device (ALDM) for the study of cognitive abilities of monkeys maintained in semi-free ranging conditions. Data accumulated during the last five years have consistently demonstrated the efficiency of this protocol to investigate individual/physical cognition in monkeys, and have further shown that this procedure reduces stress level during animal testing3. This paper demonstrates that networks of ALDM can also be used to investigate different facets of social cognition and in-group expressed behaviors in monkeys, and describes three illustrative protocols developed for that purpose. The first study demonstrates how ethological assessments of social behavior and computerized assessments of cognitive performance could be integrated to investigate the effects of socially exhibited moods on the cognitive performance of individuals. The second study shows that batteries of ALDM running in parallel can provide unique information on the influence of the presence of others on task performance. Finally, the last study shows that networks of ALDM test units can also be used to study issues related to social transmission and cultural evolution. Combined together, these three studies demonstrate clearly that ALDM testing is a highly promising experimental tool for bridging the gap in the animal literature between research on individual cognition and research on social cognition.

Assessment of Social Cognition in Non-human Primates Using a Network of Computerized Automated Learning Device ALDM Test Systems

Fagot &#38; Paleressompoulle1 have published an automated learning device (ALDM) aimed at testing individual cognitive abilities in semi-free ranging monkeys. The main goal of our protocol is to use a network of ALDM test units to study social cognition in non-human primates.

Fagot &#38; Paleressompoulle1 and Fagot &#38; Bonte2 have published an automated learning device (ALDM) for the study of cognitive abilities of monkeys ...

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 ...

Testing Tactile Masking between the Forearms

Masking, in which one stimulus affects the detection of another, is a classic technique that has been used in visual, auditory, and tactile research, usually using stimuli that are close together to reveal local interactions. Masking effects have also been demonstrated in which a tactile stimulus alters the perception of a touch at a distant location. Such effects can provide insight into how components of the body's representations in the brain may be linked. Occasional reports have indicated that touches on one hand or forearm can affect tactile sensitivity at corresponding contralateral locations. To explore the matching of corresponding points across the body, we can measure the spatial tuning and effect of posture on contralateral masking. Careful controls are required to rule out direct effects of the remote stimulus, for example by mechanical transmission, and also attention effects in which thresholds may be altered by the participant's attention being drawn away from the stimulus of interest. The use of this technique is beneficial as a behavioural measure for exploring which parts of the body are functionally connected and whether the two sides of the body interact in a somatotopic representation. This manuscript describes a behavioural protocol that can be used for studying contralateral tactile masking.

Here we explore contralateral tactile masking between the forearms in which tactile detection thresholds are modulated by vibration applied to a remote site. The details of which remote sites have an effect can tell us about how the body is represented in the brain.

Masking, in which one stimulus affects the detection of another, is a classic technique that has been used in visual, auditory, and tactile research, ...

The 4 Mountains Test: A Short Test of Spatial Memory with High Sensitivity for the Diagnosis of Pre-dementia Alzheimer's Disease

This protocol describes the administration of the 4 Mountains Test (4MT), a short test of spatial memory, in which memory for the topographical layout of four mountains within a computer-generated landscape is tested using a delayed match-to-sample paradigm. Allocentric spatial memory is assessed by altering the viewpoint, colors and textures between the initially presented and target images.
Allocentric spatial memory is a key function of the hippocampus, one of the earliest brain regions to be affected in Alzheimer&#39;s disease (AD) and impairment of hippocampal function predates the onset of dementia. It was hypothesized that performance on the 4MT would aid the diagnosis of predementia AD, which manifests clinically as Mild Cognitive Impairment (MCI).
The 4MT was applied to patients with MCI, stratified further based on cerebrospinal fluid (CSF) AD biomarker status (10 MCI biomarker positive, 9 MCI biomarker negative), and with mild AD dementia, as well as healthy controls. Comparator tests included tests of episodic memory and attention widely accepted as sensitive measures of early AD. Behavioral data were correlated with quantitative MRI measures of the hippocampus, precuneus and posterior cingulate gyrus.
4MT scores were significantly different between the two MCI groups (p = 0.001), with a test score of &#8804;8/15 associated with 100% sensitivity and 78% specificity for the classification of MCI with positive AD biomarkers, i.e., predementia AD. 4MT test scores correlated with hippocampal volume (r = 0.42) and cortical thickness of the precuneus (r = 0.55).
In conclusion, the 4MT is effective in identifying the early stages of AD. The short duration, easy application and scoring, and favorable psychometric properties of the 4MT fulfil the need for a simple but accurate diagnostic test for predementia AD.

This article describes the 4 Mountains Test (4MT), a hippocampus-dependent test of working allocentric spatial memory. The hippocampus is affected early in Alzheimer's disease (AD) and this article outlines the 4MT methodology and results of patient testing, which demonstrates the value of the 4MT in the diagnosis of pre-dementia AD.

This protocol describes the administration of the 4 Mountains Test (4MT), a short test of spatial memory, in which memory for the topographical layout of ...

The (Spatial) Memory Game: Testing the Relationship Between Spatial Language, Object Knowledge, and Spatial Cognition

The memory game paradigm is a behavioral procedure to explore the relationship between language, spatial memory, and object knowledge. Using two different versions of the paradigm, spatial language use and memory for object location are tested under different, experimentally manipulated conditions. This allows us to tease apart proposed models explaining the influence of object knowledge on spatial language (e.g., spatial demonstratives), and spatial memory, as well as understanding the parameters that affect demonstrative choice and spatial memory more broadly. Key to the development of the method was the need to collect data on language use (e.g., spatial demonstratives: &#34;this/that&#34;) and spatial memory data under strictly controlled conditions, while retaining a degree of ecological validity. The language version (section 3.1) of the memory game tests how conditions affect language use. Participants refer verbally to objects placed at different locations (e.g., using spatial demonstratives: &#34;this/that red circle&#34;). Different parameters can be experimentally manipulated: the distance from the participant, the position of a conspecific, and for example whether the participant owns, knows, or sees the object while referring to it. The same parameters can be manipulated in the memory version of the memory game (section 3.2). This version tests the effects of the different conditions on object-location memory. Following object placement, participants get 10 seconds to memorize the object&#39;s location. After the object and location cues are removed, participants verbally direct the experimenter to move a stick to indicate where the object was. The difference between the memorized and the actual location shows the direction and strength of the memory error, allowing comparisons between the influences of the respective parameters.

The Spatial Memory Game: Testing the Relationship Between Spatial Language, Object Knowledge, and Spatial Cognition

We present a protocol to explore the relationship between spatial language production, spatial memory, and object knowledge. The procedure allows experimental manipulation of, and control over, conditions of object knowledge, language at instruction, and physical location, thus teasing apart cognitive and linguistic models describing interactions between these variables.

The memory game paradigm is a behavioral procedure to explore the relationship between language, spatial memory, and object knowledge. Using two different ...

A Behavioral Test Battery for the Repeated Assessment of Motor Skills, Mood, and Cognition in Mice

Pharmacological and toxicological studies in neurodegeneration require comprehensive behavioral analysis in mice because motor dysfunctions and dysfunctions in mood and cognition are common and often shared symptoms in neurodegenerative diseases. Shown here is a behavioral test battery for motor, mood, and cognition, which can be repeatedly tested in a longitudinal study. This battery assesses the overall behavioral phenotype in mice by examining each domain of behavior with at least two independent well-accepted tests (i.e., open-field test and rotarod test for motor function, social interaction test, elevated plus maze test, and forced swim test for emotional function, and Morris water maze test and novel object recognition test for cognitive function). Therefore, this sensitive and comprehensive test battery is a powerful tool for the study of behavioral alternation in neurodegeneration.

A comprehensive behavioral test battery of motor skills, mood&#8212;including social interaction, depression, and anxiety&#8212;and cognition is designed for the repeated assessment of neurodegeneration-related behavioral changes in mice.

Pharmacological and toxicological studies in neurodegeneration require comprehensive behavioral analysis in mice because motor dysfunctions and ...

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 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 ...