Abstract
Various adaptation procedures result in changes in performance on locomotor tasks such as blind walking to a previewed target. However, some adaptation/task pairings seem to result in stronger such aftereffects than others. Prior studies have adapted Ss to treadmill walking with altered visual flow and then tested their performance on solid-ground blind walking (Rieser et al., 1995). After adaptation to abnormally slow visual flow during treadmill walking (produced when a treadmill is towed behind a trailer at a slow speed), Ss overshoot targets on the blind walking task by no more than 10–18%. Attempting to demonstrate a larger blind walking aftereffect by using the same motor context for adaptation and testing, we adapted Ss to solid-ground walking in a wide-area VR with altered visual flow. A much larger aftereffect resulted when adaptation and testing took place in the same motor context (35% after fast-flow adaptation, −10% after slow-flow). Adaptation produced no change in verbal distance judgments. However, in that study we tested blind walking performance in VR — that is, targets were previewed in VR, rather than in the real world. We ran the study again with targets previewed in the real world. The aftereffect was not as strong (20% after fast-flow, no change after slow-flow), suggesting that visual context is also important in determining adaptation's effects. We then tried varying motor context while keeping visual context constant by adapting Ss to walking on a manual treadmill in VR with altered visual flow while accelerating and decelerating. This adaptation procedure produced a very strong aftereffect when testing was done on the manual treadmill in VR, but none on solid ground. The manual treadmill may have provided a very distinct motor context (no inertial signals of physical acceleration). Overall, our results suggest the importance of both motor and sensory contexts (whether visual or vestibular) in the transfer of locomotor recalibrations.