Matching Items (5)
Filtering by
- All Subjects: Arm Configuration
- All Subjects: Neuroprosthetics
- Creators: Helms Tillery, Stephen
- Member of: Barrett, The Honors College Thesis/Creative Project Collection
Description
Determining the characteristics of an object during a grasping task requires a combination of mechanoreceptors in the muscles and fingertips. The width of a person's finger aperture during the grasp may affect the accuracy of how that person determines hardness, as well. These experiments aim to investigate how an individual perceives hardness amongst a gradient of varying hardness levels. The trend in the responses is assumed to follow a general psychometric function. This will provide information about subjects' abilities to differentiate between two largely different objects, and their tendencies towards guess-chances upon the presentation of two similar objects. After obtaining this data, it is then important to additionally test varying finger apertures in an object-grasping task. This will allow an insight into the effect of aperture on the obtained psychometric function, thus ultimately providing information about tactile and haptic feedback for further application in neuroprosthetic devices. Three separate experiments were performed in order to test the effect of finger aperture on object hardness differentiation. The first experiment tested a one-finger pressing motion among a hardness gradient of ballistic gelatin cubes. Subjects were asked to compare the hardness of one cube to another, which produced the S-curve that accurately portrayed the psychometric function. The second experiment utilized the Phantom haptic device in a similar setup, using the precision grip grasping motion, instead. This showed a more linear curve; the percentage reported harder increased as the hardness of the second presented cube increased, which was attributed to both the experimental setup limitations and the scale of the general hardness gradient. The third experiment then progressed to test the effect of three finger apertures in the same experimental setup. By providing three separate testing scenarios in the precision grip task, the experiment demonstrated that the level of finger aperture has no significant effect on an individual's ability to perceive hardness.
ContributorsMaestas, Gabrielle Elise (Author) / Helms Tillery, Stephen (Thesis director) / Tanner, Justin (Committee member) / Barrett, The Honors College (Contributor) / Harrington Bioengineering Program (Contributor)
Created2015-05
Description
Motor behavior is prone to variable conditions and deviates further in disorders affecting the nervous system. A combination of environmental and neural factors impacts the amount of uncertainty. Although the influence of these factors on estimating endpoint positions have been examined, the role of limb configuration on endpoint variability has been mostly ignored. Characterizing the influence of arm configuration (i.e. intrinsic factors) would allow greater comprehension of sensorimotor integration and assist in interpreting exaggerated movement variability in patients. In this study, subjects were placed in a 3-D virtual reality environment and were asked to move from a starting position to one of three targets in the frontal plane with and without visual feedback of the moving limb. The alternating of visual feedback during trials increased uncertainty between the planning and execution phases. The starting limb configurations, adducted and abducted, were varied in separate blocks. Arm configurations were setup by rotating along the shoulder-hand axis to maintain endpoint position. The investigation hypothesized: 1) patterns of endpoint variability of movements would be dependent upon the starting arm configuration and 2) any differences observed would be more apparent in conditions that withheld visual feedback. The results indicated that there were differences in endpoint variability between arm configurations in both visual conditions, but differences in variability increased when visual feedback was withheld. Overall this suggests that in the presence of visual feedback, planning of movements in 3D space mostly uses coordinates that are arm configuration independent. On the other hand, without visual feedback, planning of movements in 3D space relies substantially on intrinsic coordinates.
ContributorsRahman, Qasim (Author) / Buneo, Christopher (Thesis director) / Helms Tillery, Stephen (Committee member) / Barrett, The Honors College (Contributor) / Harrington Bioengineering Program (Contributor)
Created2014-05
Description
Motor behavior is prone to variable conditions and deviates further in disorders affecting the nervous system. A combination of environmental and neural factors impacts the amount of uncertainty. Although the influence of these factors on estimating endpoint positions have been examined, the role of limb configuration on endpoint variability has been mostly ignored. Characterizing the influence of arm configuration (i.e. intrinsic factors) would allow greater comprehension of sensorimotor integration and assist in interpreting exaggerated movement variability in patients. In this study, subjects were placed in a 3-D virtual reality environment and were asked to move from a starting position to one of three targets in the frontal plane with and without visual feedback of the moving limb. The alternating of visual feedback during trials increased uncertainty between the planning and execution phases. The starting limb configurations, adducted and abducted, were varied in separate blocks. Arm configurations were setup by rotating along the shoulder-hand axis to maintain endpoint position. The investigation hypothesized: 1) patterns of endpoint variability of movements would be dependent upon the starting arm configuration and 2) any differences observed would be more apparent in conditions that withheld visual feedback. The results indicated that there were differences in endpoint variability between arm configurations in both visual conditions, but differences in variability increased when visual feedback was withheld. Overall this suggests that in the presence of visual feedback, planning of movements in 3D space mostly uses coordinates that are arm configuration independent. On the other hand, without visual feedback, planning of movements in 3D space relies substantially on intrinsic coordinates.
ContributorsRahman, Qasim (Author) / Buneo, Christopher (Thesis director) / Helms Tillery, Stephen (Committee member) / Barrett, The Honors College (Contributor) / Harrington Bioengineering Program (Contributor)
Created2014-05
Description
Cochlear implants are electronic medical devices that create hearing capabilities in those with inner ear damage that results in total or partial hearing loss. The decision to get a cochlear implant can be difficult and controversial. Cochlear implants have many physical and social impacts on cochlear implant users. The aim of this study was to evaluate how patient narratives written by people with cochlear implants (or their caregivers) express issues of quality of life and personhood related to the use of this medical device. The methodology used to answer this question was a content analysis of patient narratives. The content analysis was done using grounded theory and the constant comparative method. Two sensitizing concepts, quality of life and personhood, were used and became the large umbrella themes found in the narratives. Under the major theme of quality of life, the sub-themes that emerged were improved hearing, improved communication skills, and assimilation into the hearing world. Under the major theme of personhood, the sub-themes that emerged were confidence, self-image, and technology and the body. Another major theme, importance of education, also emerged. In general, cochlear implant users and their caregivers expressed in their narratives that cochlear implants have positive effects on the quality of life of cochlear implant users. This is because almost all of the narrative writers reported improved hearing, improved communication skills, and better assimilation into the hearing world. In addition, it was found that cochlear implants do not have a significant affect on the actual personal identity of cochlear implant users, though they do make them more confident. The majority of cochlear implant users expressed that they view the cochlear implant device as an assistive tool they use as opposed to a part of themselves. Lastly, there is a need for more awareness of or access to education and therapy for cochlear implant users.
ContributorsResnick, Jessica Helen (Author) / Helms Tillery, Stephen (Thesis director) / Robert, Jason (Committee member) / Piemonte, Nicole (Committee member) / School of International Letters and Cultures (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
The human hand relies on information from surrounding environment to distinguish objects based on qualities like size, texture, weight, and compliance. The size of an object can be determined from tactile feedback, proprioception, and visual feedback. This experiment aims to determine the accuracy of size discrimination in physical and virtual objects using proprioceptive and tactile feedback. Using both senses will help determine how much proprioceptive and tactile feedback plays a part in discriminating small size variations and whether replacing a missing sensation will increase the subject's accuracy. Ultimately, determining the specific contributions of tactile and proprioceptive feedback mechanisms during object manipulation is important in order to give prosthetic hand users the ability of stereognosis among other manipulation tasks. Two different experiments using physical and virtual objects were required to discover the roles of tactile and proprioceptive feedback. Subjects were asked to compare the size of one block to a previous object. The blocks increased in size by two millimeter increments and were randomized in order to determine whether subjects could correctly identify if a box was smaller, larger, or the same size as the previous box. In the proprioceptive experiment subjects had two sub-sets of experiments each with a different non-tactile cue. The experiment demonstrated that subjects performed better with physical objects compared to virtual objects. This suggests that size discrimination is possible in the absence of tactile feedback, but tactile input is necessary for accuracy in small size discrimination.
ContributorsFrear, Darcy Lynn (Author) / Helms Tillery, Stephen (Thesis director) / Buneo, Christopher (Committee member) / Overstreet, Cynthia (Committee member) / Barrett, The Honors College (Contributor) / Harrington Bioengineering Program (Contributor)
Created2013-05