Does the Level of Difficulty in Balancing Tasks Affect Haptic Sensitivity Via Light Touch?

The purpose of this study was to determine whether the contribution of bimanual light touch varies according to the difficulty level of postural tasks (e.g., vision occlusion, height of support surface). Fourteen healthy young adults each were asked to stand in a tandem position, on a 20-cm height balance beam. Postural tasks included light touch and no touch conditions in two vision conditions, nonvision and full vision. The root mean square of amplitude of oscillation (mediolateral), mean velocity, ellipse area, and path length of the center of pressure revealed that touch conditions reduced sway to a greater extent in the elevated support surface, nonvision condition. Highly unstable balance tasks increase the optimization of light touch and affect the attenuation of postural sway.