Evaluating One Screen/ One Control Multifunction Devices in Vehicles

Multifunction in-vehicle information systems are becoming increasingly prevalent in cars. These systems typically use a centrally located display and a single control device to carry out a variety of operations including navigation, communications, entertainment, and climate control. Advantages of these systems include: conservation of dashboard space, improved styling, function integration and flexible configuration of functions. The aim of this research was to investigate potential disadvantages of these systems. Given the quantity and complexity of the information these systems provide and the attention required to operate these devices, there is concern that they may be overly difficult and distracting to use while driving. Two 2004 European luxury vehicles containing multifunctional information systems were used in this study. Both systems consisted of a centermounted LCD screen and a console-mounted primary control knob. A combination of human factors assessment techniques were used to assess the systems: 1) expert evaluations: the Transportation Research Laboratory (TRL) Checklist and heuristic evaluations, 2) user testing and 3) the occlusion test. Six human factors experts performed the expert evaluations and 12 drivers participated in the user testing and occlusion testing. Results from the expert ratings provided a detailed account of problems. Specifically, the information display format in System A helped drivers maintain a correct representation of system status and provided immediate feedback. System B, in contrast, was less successful in terms of providing informative menu labels, appropriate feedback and navigation aids. The number of tasks successfully completed was assessed for the two systems. An average of 82% passed the performance goal in System A, and only an average of 38% in System B. Although these issues are important to the design of any consumer product, they are critical to the operation of in-vehicle systems as they could impair driver performance and increase crash risk.