An experimental device for multi-directional somatosensory perturbation and its evaluation in a pilot psychophysical experiment.

Somatosensory stimulation associated with facial skin deformation has been developed and efficiently applied in the study of speech production and speech perception. However, the technique is limited to a simplified unidirectional pattern of stimulation, and cannot adapt to realistic stimulation patterns related to multidimensional orofacial gestures. To overcome this issue, a new multi-actuator system is developed enabling one to synchronously deform the facial skin in multiple directions. The first prototype involves stimulation in two directions and its efficiency is evaluated using a temporal order judgement test involving vertical and horizontal facial skin stretches at the sides of the mouth.