Auditory contact cues improve performance when grasping augmented and virtual objects with a tool.

This experiment investigated the roles of haptic and auditory contact information for the control and execution of reaching to grasp augmented (physical plus graphic) and virtual (graphic only) objects of different sizes using a tool. Haptic contact information was present when grasping augmented objects only. In half of the trials, auditory cues were provided when contact was made between the tip of the tool and the target object. Transport and grasp kinematics, as well as on spatial errors at the end of the movement were examined. Providing auditory cues at contact led to faster movements; moreover, when haptic information was not available (when grasping virtual objects), auditory cues improved spatial accuracy. Movement times increased as the object size decreased for the augmented objects, when haptic information was available, and also for the virtual objects when auditory contact cues were provided, thus following Fitts' law. However, movement times were similar for all object sizes when neither haptic nor auditory contact information was provided. These results emphasize the importance of contact information when grasping with a tool, and the benefits of auditory contact cues for improving performance.