Effects of Linear Acceleration on Passenger Comfort During Physical Driving on an Urban Road

In this exploratory study, we examined self-reports of physical discomfort among automobile passengers while being driven on an urban road. Eight adults participated as passengers in an automobile driven by a professional driver on a predetermined course through city traffic. Passengers were driven individually along the route. While underway, participants used a handheld device to indicate momentary feelings of discomfort arising from discrete vehicle motions. We continuously recorded vehicle motion in three axes of linear acceleration and 3 axes of angular velocity. We examined vehicle acceleration during the 3 s preceding each subjective response. We found that the maximum absolute acceleration required to elicit subjective discomfort was lower when vehicle acceleration changed sign (from + to -, or vice versa) than when acceleration was of a constant sign. In addition, participants' reports of discomfort during the experiment were unrelated to their prior self-reports of generalized susceptibility to motion sickness. The results suggest that our method is valid, and has the potential to offer new insights into motion sickness causality.