Language acquisition can be truly atypical in autism: Beyond joint attention.

Language profiles in autism are variable and atypical, with frequent speech onset delays, but also, in some cases, unusually steep growth of structural language skills. Joint attention is often seen as a major predictor of language in autism, even though low joint attention is a core characteristic of autism, independent of language levels. In this systematic review of 71 studies, we ask whether, in autism, joint attention predicts advanced or only early language skills, and whether it may be independent of language outcomes. We consider only conservative estimates, and flag studies that include heterogenous samples or no control for non-verbal cognition. Our review suggests that joint attention plays a pivotal role for the emergence of language, but is also consistent with the idea that some autistic children may acquire language independently of joint attention skills. We propose that language in autism should not necessarily be modelled as a quantitative or chronological deviation from typical language development, and outline directions to bring autistic individuals' atypicality within the focus of scientific inquiry.