"All of the experimental results showed that some mechanical vibration was better than none at all, but the level of vibration that statistically improved sensorimotor functions varied by test," noted Ueda.
For each test, researchers attached the device to a volunteer's non-dominant index finger and subjected the finger to six randomized vibrations that ranged from 0-150 percent of that person's vibration amplitude threshold, a value that was determined by earlier testing. The threshold value was the magnitude of vibration required for a subject to feel that the device was vibrating.
In the two-point discrimination test, two sharp points were pressed against the fingertip and volunteers reported whether they could reliably distinguish two points touching their finger versus just one. The results showed that when individuals were subjected to vibrations equal to 75 and 100 percent of their thresholds, they could sense two points that were closer together.
The single-point touch experiment involved pressing a fiber strand against each individual's finger. Subjects were asked to report if they could feel filaments of different weights touching their fingers. The volunteers could feel lighter weight filaments when exposed to vibrations up to their vibration amplitude threshold.
In the third experiment, pieces of sandpaper with different grits were glued on one side of a plastic board. Researchers then randomly selected a test piece of sandpaper and attached it to the other side of the board -- which the subjects could not see. Subjects touched the single piece of sandpaper and tried to select the matching pie
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Georgia Institute of Technology Research News