Active Movements Generate Rotation-Independent Representations for Haptic Movements

It has been reported that there are separate representations of visual and haptic movements, and that the haptic process has a rotation-independent representation for movements. This finding suggests that movement representations are formed in a different manner from object representations through visual and haptic signals because signals from visual and haptic modalities are processed in a common multimodal representation for object perception. Here, we investigated how the rotation-independent representation specific to haptic movements is generated. Our results show that rotation-independent representations of haptic movements do not appear when haptic movements passively occur. We also confirmed that active haptic movements generate rotation-independent representations. These results suggest that active movements are required to generate rotation-independent representations for haptic movements.