Incidences of asymmetries for the palmar grasp reflex in neonates and handpreference in adults

IT was hypothesized that adult handedness might be predicted from the neona tal grasp reflex. Grasp reflex was measured from right and left hand (10 tr ials for each hand) in neonates. According to significance for the differen ce between the mean grasp reflex strength from the right and left hands, th e subjects were designated as right-, left-, and mixed-handers. Adult hand preference was assessed by Edinburgh Handedness Inventory. The percentage o f left-handedness (8.3%) in neonates coincided with adult left-handedness ( 6.3-9.2%): The percentage of consistent right-hand preference In adults coi ncided with percentage of right-handedness in neonates (25.7%). The high pe rcentage of neonatal mixed-handedness was similar to that to be expected fr om the right shift model of hand preference. It was concluded that left-han dedness and consistent right-handedness may be determined prenatally, under genetic and/or hormonal control, and that a large majority of neonatal han dedness, mixed-handers, might change their hand preference in favor of righ t-handedness under socio-cultural and developmental influences of speech ce ntres. NeuroReport 10:3253-3256 (C) 1999 Lippincott Williams & Wilkins.