Increasing usability of voice activated dialing systems

Research suggests that cellular phone use while driving increases the risk of an auto accident by a factor of 4. Additionally, it has yet to be shown that hands-free phones (such as those which use voice-activated dialing sys tems (VADS)) provide any added safety benefit over manual phones. Since it has been shown that driving performance is degraded during complex conversa tions especially under demanding driving conditions it makes sense to desig n the VADS interface to be as intuitive and simple to navigate as possible in order to reduce the risk of an accident. This paper presents the results of an investigation of a commercially available voice-activated dialing sy stem under simulated driving conditions and provides recommendations for im provement of its call hows and user-interface design. Considering the call flow findings, we conclude that the voice phone book metaphor provides an a dequate mental map which helps users navigate the menu hierarchy with some minor exceptions. With regard to the user interface design findings, we con clude that any VADS could be improved by following the principles of conver sational speech such as avoiding repetition and being flexible in its handl ing of interruptions.