Over the past semester Andrew Kun, Tim Paek, Zeljko Medenica, Oskar Palinko, and I have been investigating the influence of Personal Navigation Devices (PNDs) on driving. Nowadays these devices are widespread in vehicles. They typically display the real-time location of the vehicle on a map and play spoken prompts when drivers need to turn. While such devices are less distracting than paper directions, their graphical display may distract users from their primary task of driving.
We have conducted experiments in our high fidelity driving simulator to see the influence of two PNDs on driving:
- the influence of a standard PND, with a combined visual (electronic map) and spoken output,
- and the influence of a PND with spoken output only.
The first goal of the experiments was to find out if a PND with combined output causes drivers to spend less time looking on the road ahead than a PND with spoken output only. The second goal was to examine the effects of glancing at the PND’s visual display on driving performance. We hypothesized that a PND with combined output will influence the percent dwell time (PDT) on the outside world negatively when compared to the PND with spoken output only, i.e. drivers will be more distracted by it. Our second hypothesis was that PND’s visual display will influence negatively on the driving performance. We expected an increase in the lane position and steering wheel angle variances to occur whenever drivers look away from the road.
The experiment results showed that our hypotheses were correct:
- We found that drivers using a navigation system with a graphical display indeed spent less time looking at the road compared to those using a navigation system with spoken directions only.
- Glancing at the display was correlated with higher variance in driving performance measures.
The video below shows how the PND’s visual display influences driving performance.
With respect to designing in-car navigation aids, our results seem to suggest that if users can trust a PND enough to follow the spoken directions they are given, even when they are lost, a navigation system with no visual display may be the most favorable option since visual attention and consequently driving performance will likely be improved.
This work will be presented at the AutomtoiveUI2009 conference.
Have a good one,