Mental rotation of directional tactile stimuli

Several researchers have developed haptic devices capable of rendering directional stimuli. When these devices are integrated into mobile or handheld devices, it becomes possible for a user to hold the haptic device in any orientation and thereby receive directional stimuli that may be out of alignment with rest of the world. In such cases, it becomes necessary for the user to perform a mental transformation of the directional stimuli, so that the stimuli may be understood in a fixed or global reference frame. This paper addresses two questions: 1. Can users perform such transformations and successfully interpret stimuli, and 2. What cognitive processes are involved in these transformations? In our experiments, users performed timed identification of directional tactile stimuli with their hand in a variety of orientations around a single axis. The results show that: 1. Users can successfully identify directional stimuli both quickly and accurately, even when the stimuli are rendered in a rotated reference frame, and 2. These tasks involve the mental rotation of a spatial mental representation of the stimulus, and also show evidence of embodiment effects. Furthermore, small angles of rotation (up to ~40°) incur very little cognitive cost, suggesting that tactile direction stimuli delivered through a handheld device would be robust to variations in user hand orientation.