This thesis contains six studies investigating the impact of advanced in-vehicle
information systems on the visual demands of the driver. The experiments, while
self-contained were conceived to relate together in a cohesive manner.
The first study investigated the reliability of visual behaviour assessment. Video
tape records from experimental trials were analysed post-hoc. Significant test/retest
correlations were obtained.
Experiment two considered the visual demands of the driving task without
intervention from new technologies. Results from road trials using an instrumented
vehicle suggested changes in the subject's visual scanning which could be related to
the roadway environment (i.e., rural, urban and motorway driving).
In experiment three the effects of the introduction of a driver information system
were assessed using a congestion warning device on public roads. System use
resulted in significantly greater: subjective mental workload, glance duration and
frequency, and percentage time (eyes) away from the forward view; than the in-car
entertainment system, or the control (normal driving).
Experiment four replicated experiment three in a fixed base driving simulator. It
aimed to establish the value of the simulator for the assessment of driver visual
demand. The same significant differences presented in the road trial were observed
in the simulation study.
In the penultimate study, opportunities for the reduction of driver visual demand
were investigated. The subjects were presented with: visual, auditory or visual and
auditory route guidance information. Results suggest use of auditory information to
supplement visual displays significantly reduces visual demand on the driver.
The final study considered the effect of information availability on the distribution
of visual scanning. Driver control of in-vehicle information presentation enabled
self-determination of visual scanning strategies. Information system control of
information presentation was found to disrupt the driver's visual checking. The
interface design was shown to force the driver to adopt different visual scanning
The contribution of the experimental work to the assessment of driver visual demand
is discussed and the relationships between the experiments explored.
A Doctoral Thesis. Submitted in partial fulfillment of the requirements for the award of Doctor of Philosophy of Loughborough University.