A Method for Investigating the Sensitivity of the Skin to Mechanical Vibration

Standardised method of determining vibratory perception thresholds for diagnosis and screening in neurological investigation.

“…The frequency range (Rumpf, 1889) or the disappearance time of vibrations from a tuning fork (Treitel, 1897;Pearson, 1928) used by earlier observers have been supplemented by threshold determinations by means of electromagnetic devices (Knudsen, 1928;Geldard and Gilmer, 1934;Gregg, 1951;Cosh, 1953;Verrillo, 1966). The applied voltage is commonly used as a measure of sensitivity.…”

“…This reflects the energy delivered to the tissue but not the displacement which is the adequate stimulus to the receptors (Hunt, 1961;Sato, 1961;Lindblom and Lund, 1966). Furthermore, there are several instrumental and other technical errors associated with electrical vibrators that affect vibration amplitude (Geldard and Gilmer, 1934;Gregg, 1951;Nielsen, 1975;Sherrick, 1975). A major factor is the variation in mechanical impedance and stiffness of the various tissues with consequent variations in the damping and spread of the vibration.…”

Vibrotactile Stimulation: An Investigation of Psychophysical Methods for Establishing Threshold

“…A review of the methodological aspecrs of subreqc~ent studies indicated thar a majority of the investigators employed a merhod of limits for obraining vibroracrile information, Stimuli were resented using either an ascending or descending series or in other cases a combination of the two were used and described as a bracketLng procedure (Geldard & Gilmer, 1934;Cummings, 1738;Newman, er ui., 1939;Yacorzynski Br Brown, 1941;Sherrick, 1953;Pierrel, 1955;Stevens, 1959;Verrillo, 1965Verrillo, , 1966Hahn, 1968).…”

Artifacts in the investigation of sensitivity to vibration.

“…On the assumption that the small vibrator (one mm. 2 ) stimulates primarily touch spots, it is assumed that we did not stimulate exactly the same spot on different days. In the case of the large unit (250 mm.…”

“…Both conditioned and unconditioned stimuli were regulated by a pendulum to provide a proper temporal relationship. A check on the actual vibration of the contactor was made by a technique similar to that described by Geldard and Gilmer (2) in which the vibrations are picked up by a crystal vibration detector and analyzed on the cathode-ray tube.…”