Perceiving tongue position

Two experiments on perceiving the tongue position were conducted in which naive human subjects pointed to gingival targets, or to extensions of their fingertip, with their tongue. The aim in experiment 1 was to inquire about the existence and accuracy of the perception of the horizontal position of the tongue inside and outside the mouth, and whether kinesthetic elements other than the skin might contribute to perceiving tongue position. Vertical positioning and the calibration of the sensory map that can be presumed to underlie position sense in the tongue were examined in experiment 2. It was found that position sense is equally good in the presence and absence of anesthesia of the mucosa, suggesting that the muscles, tendons, and corollary discharge contribute to position sense in the tongue. Perception of the tongue position both inside and outside the mouth is accurate, with the error in tongue positioning being about 2 degrees. Feedback improved naive subjects' accuracy very little.