Developmental Variability and Developmental Cascades: Lessons from Motor and Language Development in Infancy.

The first year of life is punctuated by explosions of growth in motor and language abilities. This is not a coincidence. The notion of developmental cascades provides a conceptual framework for considering ways in which advances in one component of a developing system can exert far-reaching and lasting change in other domains. In this article, I review evidence for the cascading effects of early motor advances on the developing communication and language system and describe how variability in the timing of these advances may alter the nature of these effects.