Different areas of skin were shown to have different degrees of compressibility. One skin site was considered more compressible than another if it showed a larger range of indentations resulting from a set range of forces. Two skin sites were found within 5 cm. of each other which demonstrated markedly different compressibilities. Such sites were quite easy to find on the ventral surface of a proximal phalange, and on the dorsum of the hand, but the region of the thenar eminence was much more homogenous with respect to compressibility. / The experimental question asked was how does skin compressibility affect psychophysical functions, while two consistently produced negatively accelerating functions describing tactile sensory intensity? A number of separate psychophysical functions were derived at different skin sites using single pulse mechanical stimuli. At each stimulation site, a subject gave magnitude estimates for a set of controlled skin indentations and for a set of controlled forces. / Out of four subjects tested, two consistently produced positively accelerating psychophysical functions, while two consistently produced negatively accelerating functions. It was predicted that if psychophysical functions based on force were affected by skin compressibility, a more compressible skin site would provide for a larger exponent. This prediction was observed in eight out of twelve cases (three skin regions on each of four subjects). Out of the eight predicted exponent changes, four were statistically significant using a regression analysis of variance. None of the four exponent changes which were counter to the prediction were statistically significant. / It was also predicted that if psychophysical functions based on skin indentation were affected by skin compressibility, a more compressible skin site would provide for a smaller exponent. This prediction was observed in eleven out of twelve cases. Out of the eleven predicted cases, five were statistically significant exponent differences. Many of the statistically insignificant exponent changes could be attributed to comparing two stimulation sites which did not have very different compressibilities. / It was apparent that skin compressibility does play a role in determining how intense a given mechanical stimulus feels. It was hypothesized that, regardless of the stimulus dimension, the difference in skin compressibility may cause a difference in the effective area of the stimulus, or the surface gradient produced by the stimulus, or both. A difference in the effective area would translate into a difference in the number of mechanoreceptors recruited. A difference in the surface gradient may cause a difference in the response of some mechanoreceptors. / An examination of the variability of the magnitude estimates indicated two things. (1) A power function model of the stimulus intensity - tactile sensory intensity relationship is better than a straight linear model. (2) A given skin indentation at a constant rate of indentation is a less ambiguous signal of intensity than a given force at a constant rate of force change. / Source: Dissertation Abstracts International, Volume: 41-03, Section: B, page: 1140. / Thesis (Ph.D.)--The Florida State University, 1980.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_74167 |
| Contributors | GREENSPAN, JOEL DANIEL., The Florida State University |
| Source Sets | Florida State University |
| Detected Language | English |
| Type | Text |
| Format | 78 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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