Hand Dominance Increases During Concurrent Bimanual Tracking: The Role of Gaze Contingencies and Visual Display

Objective To examine the effect of dual tasking on hand dominance during a bimanual visuomotor task. Background Many operators need to perform separate tasks with each hand. Yet, there is no comprehensive study examining whether the right-hand visuomotor advantage found in right handers remains stable, increases or attenuates when another task is performed concurrently with the other hand. Methods Twenty-eight right-handed participants (mean age = 22) performed 2D visuomotor tracking under either unimanual (one target, one hand) or bimanual conditions (two targets, one for each hand). Various gaze contingencies and visual displays were tested. Tracking performance of each hand was evaluated through the mean cursor-target distance. Results A clear right-hand advantage was found under all unimanual conditions. Under bimanual conditions, tracking accuracy decreased for both hands albeit more extensively for the left hand than the right when gaze was free, thus amplifying the above right-hand advantage. Prioritization of the right hand was associated with a gaze preference toward this hand. However, this increase in manual asymmetry was greatly alleviated when participants were instructed to fixate straight ahead, a benefit obtained at no cost in terms of overall tracking performance. Conclusions During bimanual/dual tracking, there is a natural tendency for right handers to prioritize their right hand. However, this effect is strongly reduced by fixating straight ahead. Application Performing separate tasks with the right and left hands is common when piloting an aircraft. Fixating straight ahead may be useful for pilots that seek to divide more equally the negative impact of dual/bimanual tasking.