Hemispatial Effects for Left- and Right-handers on a Pointing Task

The primary goal of the current study was to determine if left-handers show an advantage for each hand in its own region of space, as do right-handers. Additionally, the study aimed to determine whether a preferred-hand advantage for movement exists in a highly-practiced task. To examine these questions, 81 right- and 60 left-handers were administered the Waterloo Handedness Questionnaire (WHQ) and completed a computer-based pointing action, where kinematic data was recorded. Here, participants were required to move to a target, located to left, midline and right of the starting position, maximizing both speed and accuracy. A 3-target location (left, midline and right space) by two hand (left, right) repeated measures ANOVA was performed for each kinematic variable, for each handedness group separately. Results indicated that left-handers showed the same spatial compatibility or object proximity effect noted by other researchers in right-handers. However, no preferred-hand advantage was found, replicating the work of Bryden and Roy (1999) who showed that the existence of the preferred-hand advantage is dependent upon the degree of spatial precision required at the movement goal.