LIS verbs behave differently in expressing a reciprocal relation between their arguments depending on the class they belong to (plain verbs, agreement verbs, spatial verbs).
LIS has a reciprocal marker glossed each_other (LEXICON 3.7.4) that can be employed to express reciprocity with plain verbs that, due to articulatory restrictions, don’t mark reciprocity on the verb (SYNTAX 2.1.3.4).
ix1+2 understand each_other
‘You and I understand each other.’
Alternatively, plain verbs express reciprocity through zero marking, namely, the object slot of a transitive verb is left empty, as shown below:
ix1+3 love
‘We love each other.’
As opposed to plain verbs, agreement and spatial verbs can inflect to convey reciprocity:
i) One-handed signs, such as give, are produced as two-handed signs in which the two hands move alternatively as independent signs, thus marking the two members of the reciprocal relation through simultaneous reduplication.
dom: 1
n-dom: 2give1 1
‘We give (something) to each other.’
ii) Two-handed signs, such as donate, can realise reciprocity through sequential reduplication, namely the two-handed sign moves from the subject to the object and backwards.
every_year christmas ix3a+3badonatebbdonatea
‘Every year at Christmas they give each other a present.’
Alternatively, the two-handed sign is produced as if the two hands functioned as independent articulators, moving alternatively between the positions of the two arguments of the predicate.
dom: 1
n-dom: 2donate1 1
‘(To) donate to each other.’
The reader is referred to SYNTAX 2.1.3.4 for a more detailed description of reciprocity in LIS.