The degree to which drivers’ attention is diverted away from the primary driving task while using in-vehicle or portable devices is determined, in part, by the design and operation of the equipment. The device’s interface can affect the degree to which drivers are able to perform primary driving tasks, such as event or object detection and maintaining vehicle control. In addition, some interfaces require many button presses to operate them. Consequently, one way to minimize the risk is to establish device-related distraction assessment metrics