Technical Session 1 Summaries
Please note: Some summaries have been edited for space and clarity. The conference proceedings will contain complete abstracts and papers.
(1) Mental Workload and Task Performance for Indirect Vision Driving with Fixed Flat Panel Displays Christopher C. Smyth (U.S. Army Research Laboratory; USA)
Of interest to designers of future combat vehicles is the effect of indirect vision upon vehicle driving, and in particular the effect of the camera lens field of view (FOV). In a field study, driving performance was measured for natural and indirect vision with eight participants negotiating a road course in a military vehicle. The indirect vision system was driven with fixed panoramic flat panel, liquid crystal displays in the cab and a forward viewing monocular camera array mounted on the front roof of the vehicle and tilted slightly downward. The results are that the participants successfully drove the vehicle with indirect vision for the different FOVs of the cameras: near unity, wide, and extended. However, they drove the course faster with natural vision than they did with the indirect vision systems. Further, the course speed significantly decreased with increased camera FOV. Workload ratings show a significant increase in perceived workload with increased FOV. Most participants reported a discomfort associated with motion sickness while they were in the moving vehicle with the displays. Finally, cluster analysis of the mental workload measures supports a skills-rules-knowledge model of information processing for the driving task.
(2) Evaluation of Manual vs Speech Input When Using a Driver Information System in Real Traffic Ulrich Gärtner, Winfried König, Thomas Wittig (Robert Bosch GmbH; Germany)
This study evaluated the influence of manual and speech inputs to a Driver Information System (DIS) on driving quality, driver stress, and user acceptance. The study is part of the EU-project SENECA. Sixteen subjects took part in the experiment. A car was equipped with a modified DIS to carry out the evaluation in real traffic situations. The DIS was a standard product with manual input control elements; it was extended by the addition of a speech input system with an independent speech recogniser. Subjects were assigned 12 different representative tasks in using the different DIS devices (radio, CD player, telephone, navigation). It was found that independently of the type of task, speech input required longer operation times than manual input. In the case of complex tasks, a distinct improvement was observed in driving quality with the speech inputs. Subjective feelings of safety were also stronger with speech than with manual inputs. However, with speech input the number of glances at the mirrors and away from the road were higher. The most frequent user errors were due to problems with spelling with selecting the correct speech commands. Speech recognition errors averaged 20.6%, which suggests that recognition performance of the speech system should be improved. Improved system performance will thus be the development task in the 2nd half of the SENECA project.
Our research assessed the effects of cellular phone conversations on driving performance. When subjects were deeply involved in cellular phone conversations using either a hand-held or hands-free device, they were more than twice as likely to miss simulated traffic signals presented at the center of fixation than when they were not distracted by the cell phone conversation. By contrast, performance was not disrupted by listening to radio broadcasts or listening to a book on tape. One might argue that when subjects were conversing on a cell phone that they detected the simulated traffic signals, but that the responses to them were suppressed. To assess this, we examined the implicit perceptual memory for items that were presented at fixation but called for no response. Implicit perceptual memory was strong when subjects were not engaged in a cell-phone conversation but impaired when they were so engaged. We suggest that active participation in a cell phone conversation disrupts performance by diverting attention to an engaging cognitive context other than the one immediately associated with driving.
(4) Distraction Potential of Speech-Based Driver Interfaces John Lee, Kristi Schmidt, Toby Bral (University of Iowa; USA)
A common assumption concerning speech-based interaction with an in-vehicle information system is that the speech-based interaction does not distract driver, because the driver is not required to take his eyes off the road. This assumption does not take into consideration the cognitive demand placed on the driver. This cognitive demand may be highly dependent upon the nature of the interaction and may increase when errors occur in the interchange between the driver and the speech-based system. When the automatic speech recognition system makes an error, the driver must first recognize that an error has been made, determine how to recover from the error, trace back to the previous menu, and repeat the command to get the desired result. These additional steps and the error recovery process may place significant cognitive demands on driver. Understanding how these errors and the recovery process affects driver attention to the road is a critical design consideration for speech-based interaction with in-vehicle information systems. This paper describes an initial experiment to address this issue and provides a theoretical framework to help identify the requirements of a speech-interface needed to support easy error recovery. Because speech interactions will always be subject to human and system error, understanding how to support the robust interaction is critical in minimizing driver distraction.
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