The effect of vertical tongue loading on the position perception of the tongue.

We investigated the effects of vertical tongue loading on the position perception of the tongue. Five male and 5 female university students served as subjects. Vertical upward and downward loading forces were applied to the tongue of the subjects. Their task was to judge the perceived horizontal position of the tongue after tongue-loading directions. The means of the judgments for the control conditions (no tongue loading) were compared with the judgments for perceived horizontal position after tongue loading. The results showed that vertical tongue loading produced a shift in the perceived horizontal direction opposite to the applied force. These results fully replicated the analogous aftereffect found by Grover and Craske (1991) for horizontal tongue loading. However, the judgments of perceived horizontal position in the present study had lower variability than did those in Grover and Craske's study, suggesting that mapping of the tongue along the vertical axis is more precise than mapping along the horizontal axis.