Attentional demand evaluation for an automobile moving-map navigation system

A study was undertaken to test and evaluate the human factors design aspects of an automobile moving-map navigation system. The primary objective of the study was to assess the driver attentional demand required by the navigation system during vehicle operation. A secondary objective of the study was to assess design specifics and determine whether or not the design was optimal in terms of efficiency of use in an automotive environment.

Thirty-two driver-subjects drove a specially instrumented 1985 Cadillac Sedan de Ville on public roadways for this research. A cross-section of driver-subjects (both genders, ages 18 to 73, and driving experience from 2,000 to 40,000 miles per year) participated, and a cross·section of roadway types (residential, two-lane state route, and limited·access four-lane) and traffic conditions (light and moderate) were used as part of this research.

The driver-subjects were asked to perform a variety of tasks while operating the research vehicle. These tasks included navigation tasks normally performed while using the navigation system, as well as a wide variety of conventional automotive tasks (e.g., tuning the radio or reading the speedometer) normally performed during vehicle operation. The purpose of asking the driver-subjects to perform a variety of conventional automotive tasks was so that direct comparisons in attentional demand could be made between tasks performed daily in an automotive environment and the navigation tasks.

Twenty-one performance and behavioral measures were collected and analyzed for this research. These measures included eye—scanning and dwell-time measures, task-completion-time measures, and a variety of measures indicating driver performance and behavior.

The data analyses for these measures focused on two major goals. First, the analyses determined which tasks (both navigator and conventional) required the highest attentional demand. Second, the analyses were used to determine groups of tasks which, for all practical purposes, required equivalent attentional demand.

The results of the analyses indicated that the navigation system is a relatively effective device, useful for its intended purpose. The results also indicated that a number of design improvements are required, however, to optimize the safety and efficiency of the device. An iterative process of design improvement and further research into the effects of improved design on required attentional demand is therefore recommended.