Risky business: How assumptions about evidence can exclude autistic voices.

Gestalt Language Development has been proposed as a theoretical foundation for neurodiversity-affirming intervention, yet its adoption remains controversial. Critics cite limited high-quality research as justification for rejecting its use, raising valid concerns about its scientific backing. However, such rejection rests on two assumptions that may lead to risky clinical decisions: (1) that research evidence should be the sole or primary driver of evidence-based practice and (2) that research-backed interventions are inherently neurodiversity-affirming. Using Gestalt Language Development as an example, this letter critiques these assumptions and illustrates how over-reliance on research alone-without integrating clinical expertise and autistic perspectives-can delay meaningful, inclusive care. I argue that centering autistic voices is essential to both neurodiversity-affirming practice and evidence-based decision-making. A more balanced model of evidence-based practice is needed-one that evaluates emerging interventions not only by their research base but also by their alignment with autistic values and their impact in clinical practice.Lay AbstractMany autistic individuals and clinicians find Gestalt Language Development to be a helpful approach for supporting autistic communication. However, some researchers argue that Gestalt Language Development should not be widely used until stronger research evidence is available. This argument introduces two risks. First, it assumes that research is the only kind of evidence that matters-overlooking the value of autistic lived experience and clinical expertise in making good intervention decisions. Second, it assumes that research-based interventions are automatically neurodiversity-affirming, even when they are developed without input from autistic people. This letter argues that excluding autistic voices from intervention decisions is risky. A more balanced approach to evidence-one that includes autistic perspectives, clinical expertise, and research-leads to inclusive, more responsive, and more effective support. While research on Gestalt Language Development is still growing, real-world experiences from autistic people and families offer valuable insight into what works and why it matters.