Browsing by Subject "Haptics"

Now showing 1 - 3 of 3
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    Discriminability of simple and complex haptic vibrations in single-cell computational and human psychophysical settings
    (2017-07) Theis, Nicholas
    A multiscale, multiphysics model of the Pacinian Corpuscle (PC) was used to study the neurophysiological response to haptic vibrations in the 100-200Hz range. The computational results were compared to human psychophysical experiments, emulating the pairing of psychophysics with in vivo electrophysiology in PC research. A first assessment of this approach was made by examining the discriminability (dꞌ) of pairs of vibrotactile stimuli. The discrimination task was performed psychophysically and in silico for both one- and two-frequency stimuli. Both firing rate and inter-spike interval neural decoding schemes were used to calculate dꞌ from simulation data. Human subjects discriminated between frequencies with two components (complex stimuli) more effectively than isolated frequencies (simple stimuli), possibly due to the presence of beat frequencies in dissonant stimuli. Over a given stimulus set, in silico dꞌ values correlated well with the psychophysical data (R2 > 0.6), but when the simple and complex data were combined the model did not match the experiment (R2 < 0.1). Firing rate resulted in better predictions than inter-spike interval, and was more robust to noise. Results suggest that a single simulated PC can capture some but not all of the observed psychophysical response to a vibrotactile stimulus.
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    A Nine-Item Questionnaire for Measuring the Social Disfordance of Mediated Social Touch Technologies
    (2017-06) Mejia, Kenya
    Mediated Social Touch (MST) technologies focus on enhancing a communication experience by sensing, transmitting, and simulating social touch between remote partners. With interest in developing MST technologies continuing to grow, it is important to create standardized methods for measuring the effect of these novel systems. This work discusses the design and validation a 9-item questionnaire to measure the "Social Disfordance" of Mediated Social Touch, with three scales that focus on Social Discomfort, Communicational Expressiveness, and Need for Additional Consideration. A high degree of "social disfordance" of an MST system signifies that it may not provide the appropriate social affordances for mediating touch in a particular context. The development of the Social Disfordance of Mediated Social Touch (SDMST) instrument included a systematic literature review, expert feedback, and think-out-loud piloting that resulted in an initial set of 49 questions to be deployed in a large-scale study. Its refinement included an exploratory factor analysis with a subsequent reduction of questions and scales. The final questionnaire, with three scales and three questions each , was created using the data from 114 participants. Included is a report of its psychometric properties, including metrics of inter-item reliability, convergent validity, and test-retest validity, confirming that these properties are sufficient for future use. It concludes with examples of scoring, appropriate use, a discussion of the limitations and future work. As is a limitation for many questionnaires, the SDMSTQ should be used in addition to other validated measures in order to help create a full evaluation of a system.
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    Perception and Mechanical Properties of the Pacinian Corpuscle
    (2020-05) Held, Tiffany
    The sense of touch is processed by the somatosensory system in which mechanoreceptors are the sensory neurons that translate mechanical stimuli into neural impulses by using specialized mechanoreceptive end organs. Pacinian corpuscles (PCs), located primarily in the hairless skin of the hands and feet, are the mechanoreceptor responsible for sensing low--amplitude, high--frequency vibrations (80-1000 Hz). In this thesis, I explored how vibrotactile perception is mediated by the PCs using a combination of computational modeling, benchtop experiments on donor tissue, and psychophysical tests. There are several mechanical models of the PC, and the first part of this thesis demonstrated that a multiphysics model of a single PC contained enough details to recapitulate the trend of observed discriminability of human subjects. We showed that discriminability of sinusoidal vibrations increases as the frequency difference between the pairs increase, and we found that complex waveforms with two frequency components were more difficult to discriminate and did not follow a discernible trend. Next, we investigated the effect that Dupuytren disease (DD) has on vibrotactile perception at frequencies within the PC's range. Dupuytren disease is a progressive hand disorder in which growth and densitification of fibrous tissue in the palms eventually causes the affected fingers to bend irreversibly. DD usually presents clinically after the age of 50, affects about 3 per 10,000 adults, and is associated with alterations to the size and the internal structure of PCs. By measuring vibrotactile sensitivity in healthy and DD subjects, we found that women are more sensitive to high--frequency vibrations than men and that men with DD may exhibit reduced sensitivity compared to men without DD. We also found that, for patients in which DD presents unilaterally, the finger with DD is less sensitive than the corresponding finger on the unaffected hand. These data may serve as a useful reference to future DD researchers and may facilitate development of novel diagnostic or prognostic protocols. Finally, we designed a system to measure the viscoelastic properties of the PC and tested isolated human cadaveric PCs from donors with and without DD to better understand how the mechanoreceptor's viscoelastic properties affect vibrotactile perception.