This tongue TVSS system works by delivering electrotactile stimuli to the dorsum of the tongue via a flexible electrode array placed in the mouth. This electrode array is connected to a Tongue Display Unit via a ribbon cable passing out of the mouth. A video camera records a picture, transfers it to the TDU for conversion into a tactile image. The tactile image is then projected onto the tongue via the ribbon cable where the tongue's receptors pick up the signal. After training, subjects are able to associate certain types of stimuli to certain types of visual images. In this way, tactile sensation can be used for visual perception.