| Abstract: | A longitudinal design was used to test for a developmental relation between unimanual handedness and duplicated syllable babbling (SB). 30 infants were tested for a unimanual hand preference in their manipulation of 8 toys at weekly intervals from 5 mo of age through 8 wks after the onset of duplicated SB. Measures of Ss' unimanual handedness across weekly sessions were analyzed with respect to SB onset (mean age of onset 6.7 mo; range 5.4–8.7 mo). Ss began to demonstrate unimanual right handedness on the week of SB, whereas they did not show any significant hand preference on the preceding week(s). Ss also demonstrated a temporary loss of this hand preference for a brief period approximately 3–4 wks after SB onset. This discontinuity may reflect a disconnection syndrome of the brain hemispheres or a disruption caused by new skills mediated by the nondominant hemisphere. The developmental synchrony between unimanual handedness and duplicated SB and the curvilinear trend in unimanual handedness following SB onset suggest the presence of developmental change in hemispheric specialization or, at least, in asymmetrical organization at some brain level(s) at this point in development. (35 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) |
