Rotation-independent representations for haptic movements

Abstract

The existence of a common mechanism for visual and haptic representations has been reported in object perception. In contrast, representations of movements might be more specific to modalities. Referring to the vertical axis is natural for visual representations whereas a fixed reference axis might be inappropriate for haptic movements and thus also inappropriate for its representations in the brain. The present study found that visual and haptic movement representations are processed independently. A psychophysical experiment examining mental rotation revealed the well-known effect of rotation angle for visual representations whereas no such effect was found for haptic representations. We also found no interference between processes for visual and haptic movements in an experiment where different stimuli were presented simultaneously through visual and haptic modalities. These results strongly suggest that (1) there are separate representations of visual and haptic movements, and (2) the haptic process has a rotation-independent representation.

Active Movements Generate Rotation-Independent Representations for Haptic Movements

“…Alternatively, one might see the effect of rotation angle on reaction time differ between the Visual Reverse and Haptic Reverse conditions, which leads to the interpretation that the result might be a consequence of the use of a rotation-independent representation for the Haptic Reverse condition with passive haptic movements. However, there were no significant interactions between test sensory modalities for the reaction time, and the error rate increased with rotation angle for the Haptic Reverse condition (Figure 2b) unlike Shioiri et al (2013), who reported that the error rate was constant across all the rotation angles with active haptic movements. We could not draw the simple conclusion that the rotationindependent representation is used in the Haptic Reverse condition.…”

“…There is a dichotomy between the action-related (dorsal) pathway and the perception-or object-recognition-related (ventral) pathway in visual processing (Livingstone and Hubel, 1988;Goodale and Milner, 1992;Merigan and Maunsell, 1993), so the representation of movement information likely differs in many ways from that of object information. Indeed, a recent study revealed separate and different representations of vision and haptics for movement processing (Shioiri et al, 2013). That study showed that the mental rotation effect for haptic movements differs from that for visual movements.…”

“…Studies of mental rotation show that people have the ability to mentally rotate a visual or haptic representation and the time required to do so increases with rotation angle (Shepard and Metzler, 1971;Cooper and Shepard, 1973;Sekiyama, 1987). However, Shioiri et al (2013) revealed that the time required to mentally rotate a representation is independent of rotation angle for haptic movements but dependent on rotation angle for visual movements. This suggests that, for movements, the haptic process has a rotation-independent representation, which is different from the visual process.…”

“…Therefore, active movements might be an important factor in generating and accessing the rotation-independent representation for haptic movements. Since Shioiri et al (2013) used active haptic movements in a test phase, here we examined whether passive haptic movements are sufficient to access the rotation-independent representation. A previous study has suggested that visual imagery is involved in haptic perception (Sathian et al, 1997).…”

“…We conducted two experiments to test this hypothesis. The experiments used two-stroke patterns that were shown by visual or haptic movements as in Shioiri et al (2013). In Experiment 1, strokes were always presented passively including haptic tests.…”