Origins of manual preference and performance abilities in children and adults

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The preference to perform most unimanual tasks with one hand is an intriguing human characteristic. One notable aspect of hand preference is that certain tasks tend to elicit stronger preferences and greater selection of the preferred hand than other tasks. Likewise, the magnitude of the preferred-hand advantage depends heavily on the task examined. However, no consensus has been reached on the reason for the task dependence, and little research has been conducted to examine the developmental course of manual preference and performance abilities. Research conducted in my laboratory has attempted to better understand how the type of task influences manual preference and performance abilities in both children and adults. We have found that there are two main factors that strongly preference and performance abilities: the precision requirements of the task and the object characteristics, or affordance of the object. However, questions remain concerning how the type of task influences manual preference and performance abilities in both children and adults, how attentional resources are allocated during these tasks, and whether movement direction is an important moderating variable. Therefore, building on the previous work conducted in my laboratory, the purpose of the current research proposal is to examine a) the role of precision requirements; b) the role of tool use and object affordances; and c) the role of body-centred movement in hand preference and hand performance in left- and right-handed (LH & RH) children and adults; d) the allocation of attention in bimanual hand performance in LH and RH adults; e) language lateralization and the effects of movement direction on manual asymmetries in LH and RH adults; and f) how task features influence hand preference and performance abilities in special populations. As a great deal of controversy still surrounds the issue of the origins of hand preference and the preferred-hand advantage, and in particular the development of both, closer examination of the determinants of these behaviours will provide insight into the neural specialization of the two hemispheres. This work will ultimately contribute to a developmental theoretical model of handedness and manual performance abilities.