The grammars of sign languages

We now know that the grammars of Sign Languages can be described and analyzed with the tools of phonology, morphology, syntax and semantics. What really makes them special is that these languages are produced and perceived through other channels: we perceive them through the eyes and we articulate them in space with our hands and arms, and also with the movement and position of the torso, of the head and of the different elements in our faces. That is why we say that these languages belong to the visual-gestural modality, while Spoken Languages belong to the oral-aural modality.