Abstract
Regulation of egomotion has become a classical test bed for models of visually-guided behaviour. Much of this work has involved removing access to vision prior to movement execution. Work conducted in fixed-base and moving-platform driving simulators (e.g. Cloete & Wallis, Experimental Brain Research, 2009), has revealed that in the absence of visual feedback, participants commit highly systematic errors when attempting complex steering movements (such as lane changes and obstacle avoidance). These errors are consistent with a broad misunderstanding of steering dynamics, which leads to a startling inability to predict the effect of steering wheel manipulations on the trajectory described by the vehicle. Although informative, studies of this type test behaviour in a context quite unlike that which we experience in our everyday lives, because they involve the absence of sustained inertial forces. As a result, the contribution of other sensory systems (e.g. vestibular, somatosensory and proprioceptive) has been largely ignored. In the experiments reported here, we studied behaviour in a moving vehicle, which allowed us to assess the role of these non-visual cues. Participants were required to undertake lane-change manouevres on a 10,000sqm asphalt skidpan, with sustained visual occlusion achieved with a pair of LCD shutter goggles. Without visual feedback, participants initially produced large and systematic errors in heading similar to those found in previous studies. However, over the course of only 10 trials they were producing the correctly integrated sequence of steering wheel movements. The results suggest that extra-visual feedback can be rapidly recruited to produce successful execution of complex steering movements. Curiously, despite the improved performance, the majority of our subjects revealed no improvement in their insight into how to conduct a lane change. The results carry a number of implications for theories of dynamic re-weighting in multisensory integration.
Human Frontiers Science Projects RGP 03/2006.