Low frequency lateral acceleration and subjective ratings of acceleration intensity and driving confidence in production cars

There are few studies in the literature that relate subjective ratings to objective measures of low frequency lateral acceleration such as might be experienced whist cornering in a car. This paper reports a study where 1203 subjects drove two different cars (‘sport’ and ‘comfort’) on two different lateral acceleration trials. Objective measures of acceleration were taken, in addition to ratings of lateral acceleration intensity and confidence. It is shown that there was little difference between the peak lateral accelerations experienced in the two cars, although males chose to drive with greater lateral acceleration (i.e. at higher speed) than the females. Despite differences between the objective measures of acceleration being small, subjective data showed that the intensity of acceleration was rated higher for the comfort car than the sport car indicating that subjective ratings are context specific. Ratings of intensity were correlated with measures of peak acceleration for each car / trial combination. Drivers were more confident driving the sport car than the comfort car on the two trials. However, there was only a weak and inconsistent relationship between lateral acceleration and driving confidence. It is hypothesised that this is an example of risk homeostasis whereby drivers choose to moderate their speed (and therefore the lateral acceleration) in response to their confidence level that might be affected by a complex combination of factors.