Search

The main purpose of this study was to test the influence of music environment on hand-use preference in infants from 5 to 12 months, compared to speech environment. According to hemispheric specialization, our hypothesis was that infants would reach for objects more with their right hand in a speech context (left hemisphere), and more with their left hand in a music context (right hemisphere). 61 full-term infants aged from 5 to 12 months participated in this study. A prehension task was proposed successively in two sound environments (music and speech) in a counterbalanced order. Left-, right-movement and/or bimanual movements were scored. Results show that whatever the sound context, from 8 months a lateral right bias occurs and increases strongly. However, 5- to 7-months-old infants used more their left hand when they listen to a piece of classical music that an adult speech. Bimanual movements were more frequent at 6 and 7 months than unimanual movements in the speech condition. Results are discussed in terms of manual specialization., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Recent theories on the evolution of language (e.g. Corballis, 2009) emphazise the interest of early manifestations of manual laterality and manual specialization in human infants. In the present study, left- and right-hand movements towards a midline object were observed in 24 infants aged 4months in a constrained condition, in which the hands were maintained closed, and in a free condition. A left-hand dominance for approach movements without contact with the object, and a right-hand dominance for reaching movements with object contact was observed in the free condition. In the constrained condition reaching movements of the right hand decreased dramatically. These results are interpreted as strong evidence of manual specialization in 4-month olds, with approach movements having a localization role and reaching movements announcing future right-hand dominance for prehension and object manipulation., (Copyright 2009 Elsevier Inc. All rights reserved.)