Underwater Vibrotactile Frequency Detection in human Hairy and Glabrous Skin

Jordan Martin

Date of Award

2011

Document Type

Thesis

Degree Name

Bachelors

Department

Social Sciences

First Advisor

Bauer, Gordon

Keywords

Vibrotactile, Psychophysics, Tactile, Sensory Detection

Area of Concentration

Psychology

Abstract

The sensitivity of human vibrotactile frequency detection was compared for the hairy and glabrous skin of the hand by means of a staircase method psychophysical procedure with five subjects. Sinusoidal vibratory stimuli were presented in an underwater setting at five standard frequencies, 10, 25, 50, 100, and 150 Hz. In contrast to previous studies with mechanical contact stimuli, vibrations underwater were used to stimulate receptors sensitive to indentation of the skin and those sensitive to movement of the hairs. Results indicated that with such a stimulus, detection thresholds do not vary between hairy and glabrous skin. The hair on the dorsal hand was then depilated to determine the contribution of hair follicle afferent fibers to vibration detection. Pre-depilation skin was not significantly more sensitive than post-depilation skin on measures of velocity or displacement. Pre- and post-depilation acceleration thresholds showed a reliable but not significant difference. In a follow-up measure for one participant 3-weeks post-depilation, sensitivity to acceleration of the depilated skin recovered and surpassed that of pre-depilated skin. When compared to reports of in air contact vibrator studies, the results of this study indicated that hairy skin is as sensitive to vibration as the fingertip. These findings with an underwater stimulus provide the first example of a tactile stimulus that is equally effective in stimulating receptors in glabrous and hairy skin. The results suggest that research on vibrotactile sensitivity in human skin would benefit from further consideration of the mechanical characteristics of stimulus presentations, highlighting the importance of hair movement when comparing hairy skin to thresholds of glabrous skin. Implications for vibrotactile studies of marine animals and the development of the skin in utero are discussed.

Rights

This bibliographic record is available under the Creative Commons CC0 public domain dedication. The New College of Florida, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.

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