Unimanual hand preferences in 6-month-olds: Consistency and relation to familial-handedness

We examined the consistency of the unimanual hand preferences of 36 6-month-olds grouped on the basis of familial handedness. The hand preference of each infant was assessed three times, 1 week apart, by recording which hand the infant used to grasp and move test items. All measures of the consistency of hand preferences indicated modest consistency. The infants' hand preferences differed from those of adults in that (a) the incidence of right preference was lower than that found in adults, and (b) the relation of hand preferences to familial handedness differed from that found in adults. However, the behavior of the infants was not random: Like adults, the infants' hand preferences were more often right biased than left-biased, and a significant proportion were classified in the same way across testing sessions.