Unimanual and Bimanual Haptic Shape Discrimination

Abstract

In the current study 24 younger adults and 24 older adults haptically discriminated natural 3-D shapes (bell peppers, Capsicum annuum) using unimanual (one hand used to explore two objects) and bimanual (both hands used, but each hand explored separate objects) successive exploration. Haptic exploration using just one hand requires somatosensory processing in only one cerebral hemisphere (the hemisphere contralateral to the hand being used), while bimanual haptic exploration requires somatosensory processing in both hemispheres. Previous studies related to curvature/shape perception have found either an advantage for unimanual exploration over bimanual exploration or no difference between the two conditions. In contrast to the results of previous studies that found an advantage for unimanual exploration, the current study found that unimanual and bimanual haptic exploration produced equivalent shape discrimination performance. The current results also document a significant effect of age on haptic shape discrimination: older adults exhibited moderately reduced shape discrimination performance compared to younger adults, regardless of the mode of exploration (unimanual or bimanual)