Abstract
A number of studies have suggested functional equivalence of real locomotion and imagined locomotion (Decety et al., 1989; Plumert et al., 2005; Courtine et al., 2004). We investigated the similarity between real and imagined walking to targets in a series of four experiments of mixed within/between-subject design. In each of four experiments, participants viewed a target located on the ground-plane at an egocentric distance of up to 8 meters and were instructed to form a mental image of the target and surrounding hallway environment. Participants were then instructed to walk blindfolded to the target while spatially updating their position or to imagine walking to the target while spatially updating their imagined position. As has previously been found by others, both imagined and real walking times increased with distance to the target. However, the experiments demonstrated that imagined walking to targets times were consistently faster than blindfolded real walking to the same targets, regardless of whether or not subjects knew which of these two types of tasks they would be performing prior to viewing the targets, regardless of the order in which the two types of tasks were performed and regardless of whether the imagined walk to target was performed with vision or while blindfolded. This is in contrast to previously published studies, which found imagined walking times to be similar to blindfolded walking times to the same targets. The experiments also found imagined walking times faster than eyes-open walking to the same targets, but by an amount less than the difference compared to blindfolded walking. In evaluating these results and in considering the large issue of the functional equivalence of real locomotion and imagined locomotion, it is important to note that the between subject variability of imagined walking time is much greater than the variability of blindfolded real walking.
Acknowledgments: This work was supported by NSF grant IIS-01-21084.