Visual Contributions To Locomotor Recalibration
Journal Of Vision
Treadmill running produces several locomotor aftereffects (e.g., Anstis, 1995) that seem to derive from the novel (un)coupling of perception and action (Durgin and Pelah, 1999; Rieser et al., 1994). We have recently demonstrated overshoot in closed-loop walking tasks following closed-eye treadmill running (Durgin et al., 2000). That is, Anstis's adaptation produces Rieser's aftereffect. Here we show (Expt 1) that Rieser's counter-adaptation can reduce Anstis' aftereffect. We also show (Expt 2) that hopping aftereffects are similarly modulated by vision. EXPT 1: Subjects attempted to run in place for 20 s (eyes closed) before and after three forms of adaptation. Inadvertent forward drift was measured. Adaptation consisted of 60 s of travelling on a cart pulled at 16 kmph along an outdoor road (C), jogging on a treadmill at 6.7 kmph (T), or both simultaneously (CT). Results: After running without optic flow (T), inadvertent drift during the running in place task (3.2 m) was greater than (CT) when optic flow information had been available (2.4 m), t(11) = 2.96, p < .05. However, there was also a difference between the unadapted pretest (1.8 m) and adaptation to passive (C) travel (1.4 m), t(11) = 2.34, p < .05. Vision and action both mattered. EXPT 2: Subjects attempted to hop in place for 20 s, on each leg, following two forms of adaptation. They were adapted to forward hopping for 30 s with eyes either open or closed. Results: As predicted, forward drift was greater following eyes closed (86 cm) than eyes open (58 cm) adaptation, F(1,9) = 5.46, p < .05. In both adaptation conditions, however, there was greater drift on the adapted leg (93 cm) than on the unadapted leg (50 cm), F(1, 9) = 10.6, p < . 01. There was no reliable interaction between the two factors, F(1,9) < 1. Conclusions: Both of these experiments indicate strong contributions of vision to locomotor recalibration. Other perceptual information (e.g., kinesthetic, vestibular) may be involved as well.
Vision Sciences Society Annual Meeting
Frank H. Durgin; Laura Frances Fox , '03; and Rachel F. Kane , '02.
"Visual Contributions To Locomotor Recalibration".
Journal Of Vision.