In a likelihood alarm display (LAD) information about event likelihood is computed by an automated monitoring system and encoded into an alerting signal for the human operator. Operator performance within a dual-task paradigm was evaluated with two LADs: a color-coded visual alarm and a linguistically coded synthetic speech alarm. The operator's primary task was one of tracking; the secondary task was to monitor a four-element numerical display and determine whether the data arose from a "signal" or "no-signal" condition. A simulated "intelligent" monitoring system alerted the operator to the likelihood of a signal. The results indicated that (1) automated monitoring systems can improve performance on primary and secondary tasks; (2) LADs can improve the allocation of attention among tasks and provide information integrated into operator decisions; and (3) LADs do not necessarily add to the operator's attentional load.

How reliable must traffic information be for motorists to trust and accept such advice? This study provides data to aid the designer of advanced traveler information systems (ATIS) in selecting an appropriate level of system accuracy. The Battelle Route Guidance Simulator was used to study the effects of information accuracy and familiarity of the driving environment on objective and subjective indices of driver performance and opinion. The simulator provided real-time information and traffic video. Information was 100%, 71%, or 43% accurate. Drivers experienced either Seattle and its environs or an artificial setting that was topologically matched to Seattle. Results showed that 100% accurate information yielded the best driver performance and subjective opinion, information that was 71% accurate was still accepted and used, but information that was 43% accurate produced powerful decrements in performance and opinion. Simulated ATIS information was not used as effectively in the familiar Seattle setting. Driver trust decreased with inaccurate information but recovered---though not always fully---with subsequent accurate information.

Human factors research can be used to design safe and efficient Advanced Traveler Information Systems (ATIS) that are easy to use (Kantowitz, Becker, & Barlow, 1993). This research used the Battelle Route Guidance Simulator (RGS) to examine two important issues related to driver behavior and acceptance of ATIS technology: (1) the effect of route familiarity on ATIS use and acceptance and (2) the level of information accuracy needed for an ATIS to be accepted and considered useful. The RGS included two 486 computers that provided drivers with real-time information and traffic reports. Drivers used a touch screen to select routes on one computer monitor and watched the results of their selection (i.e., real-time video of the traffic) on a second computer monitor. Drivers could use the system to obtain information about the traffic conditions on any link before traversing a route. In this experiment, subjects were exposed to four experimental conditions involving manipulation of the driver's familiarity with the route and the reliability of the traffic information obtained from the RGS (Le., loo%, 71%, and 43% accuracy). The driver's goal was to reach the destination as quickly as possible by avoiding heavy traffic. The results indicated that drivers were able to benefit from system information when it was reliable, but not when it was unreliable. Trust ratings for the 43% accuracy group were significantly higher at the beginning of the four trials than at the end. Also, drivers were more apt to rely on the ATIS and accept information given in an unfamiliar traffic network versus a familiar one.

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An important goal of in-vehicle Advanced Traveller Information Systems (ATIS) is to allow travellers to drive safely and efficiently by supplying real-time route guidance and traffc advisory information. Since the impact of in-vehicle ATIS on driver behavior is not yet fully understood, human factors research is required to fill this gap. While on-the-road field studies are important, simulators can also be used quite effectively to investigate the complex set of parameters that modulate driver choice and behavior. The Battelle Route Guidance Simulator is a low-cost tool that has been used successfully to study driver response to advanced vehicle navigation systems. I. BENEFITS OF SIMULATIONSimulators combine many of the benefits of both laboratory and field research while avoiding some of the disadvantages associated with applying each method individually. Disadvantages associated with field research include high cost, potentially hazardous driving conditions and attendant legal restrictions, and great difficulty controlling situational and environmental variables. Disadvantages of laboratory studies include limited ability to generalize results to practical situations. Simulators minimize these disadvantages while retaining a high degree of experimental control.Automotive simulators serve a variety of purposes and can be configured in a variety of ways. Options include the use of a fixed-base vs. a motion-base, a part-task or a full-task approach, and a direct-view or projection system approach. All roads to a working driving simulator however, represent a series of compromises between costs, desired functionality, and levels of fidelity. Since figures are always in yesterday's dollars, specific numbers are not presented here, but from a review of the literature and our own experience at Battelle, low-fidelity personal computer based simulators can cost as little as $10,000 whereas high-fidelity simulation can cost over $1,000,000. Also a high-fidelity simulator can take years to develop and despite the ever increasing availability and decrease in cost of new hardware and software technology, the development of graphics software and specification files for specific simulated driving scenarios is time consuming and expensive. Much of the cost of high-fidelity simulation is 0-7803-2587-7195 $4.00 0 1995 IEEE associated with the software and hardware capacity to represent increasingly complex visual information, decreased display latency and increased visual fidelity. SIMULATOR FIDELITYThe purpose of a simulator is to emulate an operational environment. The degree to which it does so is referred to as "fidelity." Hays [ 11 has identified four dimensions of fidelity:(1) functional fidelity, the degree to which the simulator reproduces stimulus and response choices of the actual equipment, (2) behavioral fidelity, the degree to which the simulator reproduces tasks performed on the actual equipment, ( 3 ) psychological fidelity, the degree to which the user perceives the simulator to be a representation of the actual...