Abstract
We investigated the importance of biomechanical information in spatial updating by demonstrating that actions biomechanically related to walking improve performance of imagined walking in a spatial updating task. Spatial updating without vision during both real walking and imagined walking requires imagined updating of the spatial relationships that change concurrently with movement. The imagined walking task, in addition, requires an imagined biomechanical component that corresponds to the rate of imagined spatial updating. Our previous work indicated that absolute time to walk or imagine walking to targets is not equivalent; imagined walking times were consistently faster than real walking times (Kunz et al., VSS 2007). These results suggest that performance of imagined walking may be biased by incomplete perceptual-motor information. In order to test this idea, we asked participants to perform actions, concurrently with the imagined walking task, that were either biomechanically consistent or inconsistent with the act of walking. Participants viewed a target located on the ground-plane at an egocentric distance of 4, 6 or 8 meters and were instructed to form a mental image of the target and surrounding environment. They were instructed to imagine walking to the target while either stepping in place or moving their arms in a circular motion. All participants also performed real walking to the targets without vision. Real and imagined walking times were equivalent only when participants stepped in place while imagining walking, and not during the arm movement unrelated to walking. This finding suggests that stepping in place may facilitate imagined walking performance by providing information about the rate of spatial updating in imagined locomotion. Biomechanical information supplements the mental simulation of a spatial updating task during walking but may also be important in other imagined actions in which rhythm, timing or pace is critical to accurate performance.
This work was supported by NSF grant 0121084.