Similarity and Difference in Symmetry between the Visual and Haptic Motional Representations

In this research, we focus on symmetry to investigate the difference between visual and haptic motional representations. It is known in vision that symmetry about vertical or horizontal axis is easier to detect comparing with the other axis. We conducted a psychophysical experiment to examine whether symmetry process in haptic motion depends on axis orientation as in visual process. The observer's task was to respond symmetry pattern of a memorized image and the accuracy of the response was measured. Results showed similar effect of axis orientation on symmetry judgment both in visual and haptic motional perception, suggesting similarity in the two modalities. However, there were also a clear difference in axis orientation effect between visual and haptic motion conditions. Less superiority of horizontal axis was found in the haptic motion condition. This suggests that haptic motion system has a representation process independently of the one for vision