In addition to navigation displays, telephones, and various in-car entertainment systems, in-car computers that support all features associated with a standard laptop are now available, as are intelligent transport systems and wireless Internet. Although speech-based interfaces can minimize direct interference with driving, the cognitive demands associated with such systems may still cause distraction. The article reports on a study of the effects on driving performance of an in-vehicle simulated "E-mail" message system; E-mails were either system controlled or driver controlled. The study used a high-fidelity, fixed-base driving simulator to test 19 participants on a car-following task. The participants faced virtual traffic scenarios that varied in driving demand. Results show that drivers compensated for the secondary task by adopting longer headways but showed reduced anticipation of braking requirements and shorter time to collision. Drivers were also less reactive when processing E-mails, demonstrated by a reduction in steering wheel inputs. In most circumstances, there were advantages in providing drivers with control over when E-mails were opened. However, during periods without E-mail interaction in demanding traffic scenarios, drivers showed reduced braking anticipation. The authors conclude that the negative impact on safety may be reduced somewhat with driver-controlled interface designs.
Abstract