Abstract
Recently we have found that during visually-guided grasping tasks, individuals prefer to use their right hand to pick up an object, particularly if it is small in size. However, during haptically-guided (using touch) grasping tasks, a significant increase in left-hand use emerges, particularly when grasping small objects (which require finer discrimination). Is the increase in left-hand use due to a left-hand/right-hemisphere specialization for haptic discrimination? To address this question, blindfolded participants were instructed to haptically assess and replicate an array of small objects (LEGOs) as quickly and accurately as possible. Located on a building plate in front of the participant was an array of five different blocks to be replicated (reference array) using a closer array of ten blocks (sample array). Using hapsis, participants would choose from and remove the blocks needed from the sample array and place them onto a smaller fixed building plate directly in front of them, creating a replica of the reference array. Participants completed the task bimanually, or exclusively using the left or right hand (counterbalanced between participants). Measurements included time to complete each trial and the number of mistakes made by each hand per trial. Additionally, we measured the time each hand spent discriminating the arrays during the bimanual trials. Results showed that participants were fastest at completing each trial when they used both hands. However, for these trials participants made significantly more mistakes when compared to the left but not the right hand. Furthermore, participants spent significantly more time discriminating the blocks with their left hand during the bimanual trials. The results align with previous findings of a left-hand/right-hemisphere specialization for haptic discrimination, which may explain the increase in left-hand use for grasping without vision. Furthermore the results suggest that during a haptically-guided bimanual task, hemispheric cross-talk may interfere with performance.
Meeting abstract presented at VSS 2014