The phonological description of lexical signs in LIS does not focus only on hand movements articulated with a certain handshape and orientation in a certain location. Another phonological parameter that needs to be considered is represented by non-manuals. This term includes facial expressions, head and body movements.
Focusing on mouth patterns, LIS signs make use of mouth gestures and mouthings. Mouth gestures are intended as mouth movements that do not have any connection with Italian. Mouthings are mouth movements producing the visual representation of Italian words.
Mouth gestures and mouthings can be phonologically distinctive, as proved by the existence of minimal pairs. For example, fresh and not_yet are both two-handed signs articulated with F handshape and a repeated lateral movement in the neutral space. They differ in non-manuals only: fresh is accompanied by mouthing (the mouth voicelessly reproduces the equivalent spoken word, i.e. fresco), whereas not_yet is accompanied by mouth gesture [sss] (the mouth releases air as in sibilant [s]) and lateral head shakes.
‘fresco’
a. fresh (mouthing)
[sss]
b. not_yet (mouth gesture)
Mouth gestures and mouthings are described in detail in the next sections.