In this US study of 257 participants, both youth and adult drivers took a vehicle home and practiced using the IVIS. The purpose of this study was to examine the cognitive workload of an internal distraction, the IVIS, while driving. After using the vehicle for five days, results indicated that the workload experienced by the drivers was moderate to high, averaging 3.34 on a 5-point scale (with 1 being least distracting and five being most distracting). Drivers required 27 seconds to return to baseline levels of performance following a single task. This means that at 25 mph, drivers could travel the length of more than 3 football fields before their full attention returned to the driving task.
The workload experienced by older drivers was greater than that experienced by younger drivers performing the same tasks. In addition, IVIS interactions that were difficult on the first day were still relatively difficult to perform after five days of practice, meaning that the level of distraction did not decline as drivers become familiar with the vehicle system.
Authors concluded their results challenged the assumption that voice-based interactions are easier and reduce the cognitive load of drivers. As such, the cognitive demands of in-vehicle systems on drivers may be more distracting and negatively affect safe driving. They suggested that more robust and intuitive systems with lower levels of complexity and shorter task durations would have a lower cognitive workload than more rigid, error-prone, time-consuming ones.
Strayer, D.L., Cooper, J.M., Turrill, J., Coleman, J.R., Hopman, R.J. (2015) Measuring cognitive distraction in the Automobile III: A comparison of ten 2015 in-vehicle information systems. AAA Foundation for Traffic Safety, 1-44.