Each verb comes with a set of obligatory participants that need to be expressed as arguments in the sentence. However, we can extend the basic argument structure of a verb by adding an argument that carries a non-obligatory thematic role. For example, the verb chat in DGS requires at least an agent that does the chatting, but we can add a theme to chat about with the help of the specialized person agreement marker pam-about which sometimes also occurs with the mouthing /über/ [Lexion 3.3.4], [Morphology 3.1.1].
ix1 pam_about2 can chat
‘We could chat about you.’
Another such agreement marker glossed pam-for adds a beneficiary to verbs like buy, which otherwise only take an agent and a theme:
ix1 book pam-for2 buy can
‘I can buy a book for you.’
Classifier predicates that express a change of location may be causativized through the use of a handling classifier [Morphology 5.1.3]. When the predicate describes a spontaneous change of location as in (a), its handshape represents the theme via a whole entity classifier. w represents the shape of the theme book. To add a human causer to the argument structure of such classifier predicates, the whole entity classifier is replaced by a handling classifier like V in (b). By depicting how a human causer would handle an object like a book, such classifiers encode both their causer and their theme argument.
a. tablea book cl(w):‘book-fall-off_a’
‘The book fell off the table.’
b. shelfa man book cl(V):put_book_in_a
‘The man put the book on the shelf.’