The Haptic modality is a composite of two modalities: The Tactile and Proprioceptive modalities.
This affords the deaf community with a communication bridge that is capable of both rapid social intercourse and cumulative learning.
I might add, that in the case of Sign Language, the expressive transducer for the Visual Modality includes more than just the hand.
It incorporates both hands, the upper torso and the face and head.
The Haptic Modality is yet another channel within the brain that can support the processes of language.
This modality, however, is a composite of two more basic modalities--the Tactile and the Proprioceptive Modalities.
The Tactile Modality is the sense of touch and, of course, is very familiar to us. Its receptive transducer is the the system of nerve endings just under the skin.