A driving simulator experiment was conducted to determine the effects of entering addresses into a navigation system during driving. Participants drove on roads of varying visual demand while entering addresses. Three address entry methods were explored: word-based speech recognition, character-based speech recognition, and typing on a touch-screen keyboard. For each method, vehicle control and task measures, glance timing, and subjective ratings were examined. During driving, word-based speech recognition yielded the shortest total task time (15.3 s), followed by character-based speech recognition (41.0 s) and touch-screen keyboard (86.0 s). The standard deviation of lateral position when performing keyboard entry (0.21 m) was 60% higher than that for all other address entry methods (0.13 m). Degradation of vehicle control associated with address entry using a touch screen suggests that the use of speech recognition is favorable. Speech recognition systems with visual feedback, however, even with excellent accuracy, are not without performance consequences. Applications of this research include the design of in-vehicle navigation systems as well as other systems requiring significant driver input, such as E-mail, the Internet, and text messaging.

To gain insight as to when telematics can be distracting, 16 participants drove a simulator on roads with long curves of several different radii. Participants read electronic maps displayed in the center console while both parked and driving. In separate trials, the visual demand/workload of the same straight and curved sections was measured using the visual occlusion technique. Visual demand was correlated with inverse curve radius.As visual demand increased, driving performance declined. Participants made shorter glances at the display, made more of them, but waited longer between glances. Overall, task completion time increased when the task was performed while driving (versus while parked), except for short duration tasks (a single glance or under 3 seconds timed while parked), where task time decreased. While driving, task completion times were relatively unaffected by the driving workload.

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