Abstract
While the left and right hands no doubt share a degree of spatial and temporal coupling during rhythmic tasks (e.g. Kelso et al. 1985), research into the temporal linkage of the hands in reaching movements is scant. Kelso et al. (1979) reported that both hands move in near perfect synchrony during such tasks, while contrasting reports of independent error correction in each limb suggest no such entrainment (Boessenkool et al. 1999). Asymmetries in the performance of each hand during unimanual reaching tasks have been documented, including an advantage for the left hand in reaction time (an earlier process such as attention or visuo-spatial localisation) and a right hand advantage for accuracy and movement duration possibly mediated by preferential online monitoring (an intentional process, i.e. Peters 1981). In addition, studies of unimanual reaching have noted a clear discrepancy in performance when reaching across the body midline (i.e. Carey et al., 1996). There is however a distinct lack of research into how the dominant hand performs, in relation to the non-dominant hand when making bimanual reaches, especially to different sides of space. To examine any attentional and intentional asymmetries across the hands, participants made bimanual reaches to 2 equidistant targets in right, left, or central space. Upon landing, a further unimanual movement, to a target appearing near the peak velocity of the first (bimanual) movement. No difference in (the unimanual) reaction time was found. In a further study, unimanual reaches to targets across the workspace were compared with identical movements in a bimanual context (i.e. the measured movement accompanied by a concurrent reach of the other hand). These data will demonstrate which arm is yoked to the other, as bimanual movements into ipsilateral space for the coupled arm would be slowed by the other arm, reaching into its contralateral workspace.
6th Century Studentship from University of Aberdeen