Modelling visual-vestibular integration and behavioural adaptation in the driving simulator
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It is well established that not only vision but also other sensory modalities affect drivers' control of their vehicles, and that drivers adapt over time to persistent changes in sensory cues, for example in driving simulators, but the mechanisms underlying these behavioural phenomena are poorly understood. Here, we consider the existing literature on how driver steering in slalom tasks is affected by down-scaling of vestibular cues, and propose a driver model that can explain the empirically observed effects: Initially decreased task performance and increased steering effort, and partial reversal of these effects with prolonged task exposure. Unexpectedly, the model also reproduced another empirical finding: A local optimum for motion down-scaling, where path-tracking is better than with one-to-one motion cues. Overall, the results imply that: (1) Drivers make direct use of vestibular information as part of determining appropriate steering, and (2) motion down-scaling causes a yaw rate underestimation phenomenon, where drivers behave as if they perceive the simulated vehicle to rotate more slowly than it is. However, (3) in the slalom task, limited such underestimation brings a path-tracking benefit. Furthermore, (4) behavioural adaptation, as empirically observed in slalom tasks, may occur due to (a) down-weighting of vestibular cues, and/or (b) increased sensitivity to control errors, in determining when to adjust steering and by how much, but (c) seemingly not in the form of a full compensatory rescaling of the down-scaled vestibular input. The analyses presented here provide new insights and hypotheses about simulator driving, and the developed models can be used to support research on multisensory integration and behavioural adaptation in both driving and other task domains.
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