Analyzing the Influence of Mental Workload on Vestibulo-Ocular Reflex While Driving Using a Computational Model

The vestibulo-ocular reflex (VOR) is a reflexive eye movement that is generated in a direction opposite to that of the head movement and is affected by mental workload (MWL). In a previous study, VOR was modulated by providing a mental task when participants gazed at a fixation point and were exposed to unpredictable body motion induced by a motion platform; the modulation was described by changes in the parameter of the VOR computational model. However, further studies are required to determine whether these results are valid when participants actively operate a vehicle in an outdoor environment, such as driving. Therefore, in the present study, an experiment was conducted to investigate the influence of a mental task for car drivers based on a parameter of the VOR model. The MWL during the experimental trials was evaluated via the weighted workload (WWL) score calculated from the NASA-Task Load Index. Specifically, the eye and head movements were measured when participants drove a car in situations with and without a mental task. The experimental results indicated that the self-motion estimation parameter of the model decreased, and the WWL score increased with the addition of a mental task. The results suggest that the influence of MWL on VOR during driving can be described by the self-motion estimation parameter of the model.