Definite articles may be accompanied by special facial expressions conveying definiteness (PRAGMATICS 1.2). They typically include raised eyebrows, chin up, contracted cheeks, and mouth slightly open. In some cases, squint eyes may also be produced.
Figure: Non-manuals marking definiteness
It has been observed that these non-manuals are not compulsory. Their use can vary across signers and across contexts. When produced, they highlight the fact that the referent has already been mentioned in the discourse. As for their distribution, these non-manuals can: i) be omitted, ii) co-occur with the definite article only, or iii) coextend over the whole noun phrase.
Indefinite articles are usually accompanied by facial expressions conveying indefiniteness (PRAGMATICS 1.3), such as backward-tilted head and mouth-corners down.
Figure: Non-manuals marking indefiniteness