Preschool language ability is predicted by toddler hand preference trajectories.

Prior work has found links between consistency in toddler handedness for the fine motor skill role-differentiated bimanual manipulation (RDBM), and language development at 2 and 3 years of age. The current study investigated whether consistency in handedness from 18 to 24 months (N = 90) for RDBM predicts receptive and expressive language abilities assessed using the Preschool Language Scales 5th edition (PLS-5) at 5 years old. Latent class growth analyses identified 3 stable RDBM hand preference trajectories: a left hand preference with moderate right hand use (left-moderate right), a right hand preference with moderate left hand use (right-moderate left), and a right hand preference with only mild left hand use (right-mild left). At 5 years of age, children with a right-mild left handedness trajectory as toddlers scored significantly higher on receptive and expressive language abilities compared to children with a left-moderate right hand preference. Children with a right-mild left hand preference for RDBM also scored significantly higher on receptive language abilities compared to children with a right-moderate left RDBM hand preference. Children with left-moderate right and children with a right-moderate left hand preference for RDBM as toddlers did not differ in receptive or expressive language abilities at 5 years. Results indicate that individual differences in hand preference consistency for fine motor skill in toddlerhood have cascading effects on language outcomes into the preschool years. (PsycINFO Database Record (c) 2020 APA, all rights reserved).