Previous linguistic research has described the formal properties of the transitive construction, which prototypically expresses causative events, in different languages of the world. However, little has been studied about the unfolding of these properties in spontaneous speech and, especially, in the input to children. This would allow to determine the evidence available to the child so (s)he can identify the construction and infer the meaning prototypically associated with transitive frames. The present work studies the frequency, consistency, and co-occurrence of syntactic (quantity of nominals and order of constituents) and morphological (affixes) transitivity cues on the Toba/Qom input to three male children and a female child (M=1;9) from Chaco (Argentina). The results show that argument omission is frequent and that there are not two orders that discriminate transitivity. Although they compensate for argument elision in 20% of the input, morphological cues are mostly absent, especially in child-directed speech. In nearly half of the sample, the syntactic and morphological properties do not provide consistent information about the transitivity of the clause. The most consistent values of both morphological and syntactic cues rarely co-occur.
