Learning word-order constraints under conditions of object ellipsis

It is generally assumed that the nature of the input children hear, when combined with innate capacities for (language) learning, is sufficiently rich for language acquisition to succeed despite the presence of ungrammatical utterances. Little attention, however, has been given to how children learn grammatical constructions that are rare in the input, where both overt positive evidence and implicit negative evidence are limited. Such cases provide a unique window of opportunity for exploring the various language-learning strategies children use, whether these exhibit certain "innate" semantic or syntactic predispositions, or whether more general learning mechanisms, such as statistical inference, are involved. This paper examines children's acquisition of double-object applicative constructions in the Bantu language Sesotho, where evidence for the order of postverbal objects is absent from the input, due in part to the high instance of "unspecified object deletion," or object ellipsis. It finds that although three-to four-year-olds perform above chance on forced-choice elicited-production tasks, eight-year-olds are still not adult-like in their use of the syntactic restrictions that govern these constructions. The paper raises questions regarding the types of learning strategies children use under conditions of ellipsis, and the implications this has for theories of language acquisition.