This work explores how the availability of visual and haptic feedback affects and kinematics of reaching performance in a tabletop virtual environment. Eight subjects performed reach-to-grasp movements toward target objects of various sites in conitions where visual and haptic feedback were either present or absent. It was found that movement time was slower when visual feedback of the moving limb was not available. Further MT varied systematically with target size when haptic feedback was available (i.e. augmented targets), and thus followed Fitts' law. However, movement times were constant regardless of target size when haptic feedback was removed. In depth analysis of the reaching kinematics revealed that subjects spent longer decelerating toward smaller targets in conditions where  haptic feedback was available. In contrast, deceleration time was constant when haptic feedback was absent. These results suggest that visual feedback about the moving limb and veridical haptic feedback about object contract are extremely important for humans to effectively work in virtual environments.
['Andrea H. Mason', 'Walji M', 'Elaine J. Lee', 'Christine L. MacKenzie']
Reaching movements to augmented and graphic objects in virtual environments