Toddling into language: precocious language development in motor-impaired children with spinal muscular atrophy

One of the most compelling topics of neurolinguistic debate is whether language has its own domain or is mediated by the same network that processes other cognitive, perceptual, and sensorimotor functions. To examine the relation between motor and language development we have collected data on motor-impaired children with Spinal Muscular Atrophy (SMA) aged 18–35 months. Analysis shows normal progress in vocabulary but marked precocity in over-regularisation, a sign of early grammar development. Our finding supports the view of a separate learning system for grammar but cannot be explained by the classical account of a grammar module. It rather appears as if children with SMA explore language in place of a world they cannot reach, building grammatical knowledge while able-bodied toddlers are engaged with the physical environment. We propose that procedural learning which serves the acquisition of sensorimotor skills also has a role in language development.