Why Sign Language Research Is Essential for Understanding Language and Language Disorder

Sign language research has often been framed as supplementary to spoken language studies. In this article, I argue that sign language research is not only equal in value but also essential to understanding the human language faculty and its disorders.

I present three arguments: that sign language reveals phenomena unobservable in speech, enables the testing of otherwise untestable hypotheses, and helps disentangle speech from language.

Drawing on research with deaf children with autism and other language disorders, I demonstrate how signed languages can transform both theoretical models and clinical approaches to language impairment.

Sign languages provide a unique empirical lens through which to view linguistic and clinical phenomena that would otherwise remain obscured.