Abstract
Adapting to a mismatch between speed of visual motion and biomechanical walking will change later visually directed locomotion, indicating a recalibration of the link between perception and action (Rieser et al., 1995). We investigated the recalibration effect for imagined walking, a task which has been proposed to be functionally similar to overt locomotion (Decety et al., 1989). In a pre-test, participants were instructed to imagine walking to targets on the floor at 6, 8, and 10 meters, while timing their imagined walking using a stopwatch. Participants then walked on a large platform treadmill for 10 minutes at a constant rate of 1.3 m/sec while viewing visual motion of a computer-rendered hallway projected onto three screens providing approximately 180-degree horizontal field of view. Speed of visual motion was either .5x their biomechanical speed (visually slower) or 2x their biomechanical speed (visually faster). Participants then repeated the imagined walking task in a post-test. A comparison of pre- and post-test imagined walking times revealed results consistent with the recalibration of walked distance seen in overt walking tasks. Post-test versus pre-test times increased about 15% in the visually slower condition and decreased about 15% in the visually faster condition. This evidence of a recalibration effect in the absence of overt action during pre-test and post-test supports the notion of a functional equivalence between overt and imagined actions, but also suggests that a biomechanical response is not necessary for a recalibration of the perception and action coupling.
This work was supported by NSF grant IIS-01-21084.