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Abstract:
We investigate the contribution of vestibular information to the perception of one's own walking speed. If vestibular information plays a role, we expect perceived walking speed to be lower during walking in place on a treadmill than during walking at the same speed over solid ground, because the forward acceleration of the head is lower during walking in place and therefore the vestibular stimulation is much reduced.
To test this hypothesis, we used a circular treadmill setup, consisting of a large turntable and a motorized handlebar to guide participants at a given speed. Participants judged their walking speed
in a 2IFC task, with vision and hearing excluded. We used different standard walking speeds, presented during walking in space behind the handlebar. Each standard speed was compared with nine test speeds presented during walking in place on the rotating turntable. Participants indicated in
which of the two intervals their walking speed appeared to be faster. We conducted two experiments: In the first experiment we compared walking in place with walking
through space. In the second experiment we compared walking in place with a motion cue
condition. In the motion cue condition subjects initially started to walk through space and only after the initial acceleration phase the platform started to counteract the motion of the subjects until they finally walked in place. This way subjects received the initial vestibular motion cue and only
afterwards walked in place. The question was whether this initial motion cue helps to perceive walking speed veridically.
The results showed that walking speed is indeed underestimated when walking in place relative to the full motion condition and that this underestimation increases with increasing standard walking speeds. The results are, however, different for the motion cue condition, were we found no apparent
difference with walking in place. Taken together, this suggests a role for vestibular information in the perceptual estimation of walking speed, and that the vestibular information gathered during the steady state phase plays a significant role in the perception of walking speed.
