The ironies of vehicle feedback in car design.

Car drivers show an acute sensitivity towards vehicle feedback, with most normal drivers able to detect 'the difference in vehicle feel of a medium-size saloon car with and without a fairly heavy passenger in the rear seat' (Joy and Hartley 1953-54). The irony is that this level of sensitivity stands in contrast to the significant changes in vehicle 'feel' accompanying modern trends in automotive design, such as drive-by-wire and increased automation. The aim of this paper is to move the debate from the anecdotal to the scientific level. This is achieved by using the Brunel University driving simulator to replicate some of these trends and changes by presenting (or removing) different forms of non-visual vehicle feedback, and measuring resultant driver situational awareness (SA) using a probe-recall method. The findings confirm that vehicle feedback plays a key role in coupling the driver to the dynamics of their environment (Moray 2004), with the role of auditory feedback particularly prominent. As a contrast, drivers in the study also rated their self-perceived levels of SA and a concerning dissociation occurred between the two sets of results. Despite the large changes in vehicle feedback presented in the simulator, and the measured changes in SA, drivers appeared to have little self-awareness of these changes. Most worryingly, drivers demonstrated little awareness of diminished SA. The issues surrounding vehicle feedback are therefore similar to the classic problems and ironies studied in aviation and automation, and highlight the role that ergonomics can also play within the domain of contemporary vehicle design.