Mediated social touch: a review of current research and future directions

Combined psychophysical and neurophysiological research has resulted in a relatively complete picture of the neural mechanisms of tactile perception. The results support the idea that each of the four mechanoreceptive afferent systems innervating the hand serves a distinctly different perceptual function, and that tactile perception can be understood as the sum of these functions. Furthermore, the receptors in each of those systems seem to be specialized for their assigned perceptual function.

Sensory substitution systems provide their users with environmental information through a human sensory channel (eye, ear, or skin) different from that normally used, or with the information processed in some useful way. We review the methods used to present visual, auditory, and modified tactile information to the skin. First, we discuss present and potential future applications of sensory substitution, including tactile vision substitution (TVS), tactile auditory substitution, and remote tactile sensing or feedback (teletouch). Next, we review the relevant sensory physiology of the skin, including both the mechanisms of normal touch and the mechanisms and sensations associated with electrical stimulation of the skin using surface electrodes (electrotactile (also called electrocutaneous) stimulation). We briefly summarize the information-processing ability of the tactile sense and its relevance to sensory substitution. Finally, we discuss the limitations of current tactile display technologies and suggest areas requiring further research for sensory substitution systems to become more practical.