Infants with a clear hand preference show advanced language ability as toddlers
In the study, Nelson measured handedness – the tendency to use one hand more naturally than the other – in different ways according to the age-appropriate motor level. She looked at how infants used their hands to pick up toys and compared it to how they used their hands in combination to manipulate toys as toddlers.
"We can't ask an infant to write, as we might do with an adult participant," Nelson said. "So a challenge for researchers studying the development of handedness is to choose tasks that are fun and engaging for the child and sufficiently challenging without being frustrating."
The study suggests there may be an advantage to having consistent hand preference as an infant. Results showed children who had clear early hand preference performed better on language skills tests than those who did not develop handedness until toddlerhood. Those who were inconsistent in their hand use as infants, but developed a preference for the left or right hand as toddlers, had language scores in the typical range for their age.
"We know that when children enter school they vary in their language and fine motor abilities, and these differences are linked to later academic achievement," Nelson said. "Our larger goal in this work is to identify how language and motor skills are linked in development and to identify earlier markers of school readiness."
Nelson tracked 38 children over 16 monthly visits – nine infant visits at 6 to 14 months of age, and seven toddler visits at 18 to 24 months of age. Language skills were measured by the Bayley Scales of Infant and Toddler Development – an individually administered test designed to assess developmental functioning of infants and toddlers. Some children showed a clear right-hand preference during the infant visits and continued to be right-handed as toddlers. Others did not show a clear hand preference as infants, but were either right or left-handed by age two.