Connecting Environmental and Genetic Explanations for Nonlinear Language Development in Infancy and Toddlerhood

Language development is not linear, regardless of the lens through which it is examined. Across both comprehension (i.e., receptive vocabulary) and production (i.e., expressive vocabulary, grammar), development is characterized by slow and gradual progress followed by sudden spurts. For example, comprehension is thought to improve drastically around 14 months of age; while infants exhibit knowledge of a few words prior to this time, their word recognition quickly improves after this point (1). Expressive vocabulary knowledge is also slow at first; typically developing infants go from knowing just a few words to knowing at least 50, but typically more than 100, between 18 and 24 months of age (2).
Source: Biological Psychiatry - Category: Psychiatry Authors: Tags: Early Career Investigator Commentary Source Type: research