Alarm mistrust in automobiles: how collision alarm reliability affects driving

As roadways become more congested, there is greater potential for automobile accidents and incidents. To improve roadway safety, automobile manufacturers are now designing and incorporating collision avoidance warning systems; yet, there has been little investigation of how the reliability of alarm signals might impact driver performance. We measured driving and alarm reaction performances following alarms of various reliability levels. In Experiment One, 70 participants operated a driving simulator while being presented console emitted collision alarms that were 50%, 75%, or 100% reliable. In Experiment Two, the same participants were presented spatially generated collision alarms of the same reliability levels. The results were similar in both experiments: alarm and automobile swerving reactions were significantly better when alarms were more reliable; however, drivers still failed to avoid collisions following reliable alarms. These results emphasize that alarm designers should maximize alarm reliability while minimizing alarm invasiveness.     

Preliminary study of behavioral and safety effects of driver dependence on a warning system in a driving simulator

Warning systems are being developed to improve traffic safety using visual, auditory, and/or tactile displays by informing drivers of the existence of a threat in the roadway. Behavioral and safety effects of driver dependence on such a warning system, especially when the warning system is unreliable, were investigated in a driving-simulator study. Warning-system accuracy was defined in terms of miss rate (MR) and positive predictive value (PPV) (PPV is the fraction of warnings that were correct detections). First, driver behavior and performance were measured across four warning-system accuracy conditions. Second, the authors estimated the probability of collision in each accuracy condition to measure the overall system effectiveness in terms of safety benefit. Combining these results, a method was proposed to evaluate the degree of driver dependence on a warning system and its effect on safety. One major result of the experiment was that the mean driving speed decreased as the missed detection rate increased, demonstrating a decrease in driver's reliance on warnings when the system was less effective in detecting threats. Second, both the acceleration-pedal and brake-pedal reaction times increased as the PPV of the warning system decreased, demonstrating a decrease in driver compliance with warnings when the system became more prone to false alarms. A key implication of the work is that performance is not necessarily directly correlated to warning-system quality or trends in subjective ratings, highlighting the importance of objective evaluation. Practical applications of the work include design and analysis of in-vehicle warning systems.     

Semantic congruency of auditory warnings

Abstract

The aim of this study was to explore operator experience and performance for semantically congruent and incongruent auditory icons and abstract alarm sounds. It was expected that performance advantages for congruent sounds would be present initially but would reduce over time for both alarm types. Twenty-four participants (12M/12F) were placed into auditory icon or abstract alarm groupings. For each group both congruent and incongruent alarms were used to represent different driving task scenarios. Once sounded, participants were required to respond to each alarm by selecting a corresponding driving scenario. User performance for all sound types improved over time, however even with experience a decrement in speed of response remained for the incongruent iconic sounds and in accuracy of performance for the abstract warning sounds when compared to the congruent auditory icons. Semantic congruency was found to be of more importance for auditory icons than for abstract sounds.

Practitioner Summary: Alarms are used in many operating systems as emergency, alerting, or continuous monitoring signals for instance. This study found that the type and representativeness of an auditory warning will influence operator performance over time. Semantically congruent iconic sounds produced performance advantages over both incongruent iconic sounds and abstract warnings.     

A comparison of tactile, visual, and auditory warnings for rear-end collision prevention in simulated driving

OBJECTIVE: This study examined the effectiveness of rear-end collision warnings presented in different sensory modalities as a function of warning timing in a driving simulator. BACKGROUND: The proliferation of in-vehicle information and entertainment systems threatens driver attention and may increase the risk of rear-end collisions. Collision warning systems have been shown to improve inattentive and/or distracted driver response time (RT) in rear-end collision situations. However, most previous rear-end collision warning research has not directly compared auditory, visual, and tactile warnings. METHOD: Sixteen participants in a fixed-base driving simulator experienced four warning conditions: no warning, visual, auditory, and tactile. The warnings activated when the time-to-collision (TTC) reached a critical threshold of 3.0 or 5.0 s. Driver RT was captured from a warning below critical threshold to brake initiation. RESULTS: Drivers with a tactile warning had the shortest mean RT. Drivers with a tactile warning had significantly shorter RT than drivers without a warning and had a significant advantage over drivers with visual warnings. CONCLUSION: Tactile warnings show promise as effective rear-end collision warnings. APPLICATION: The results of this study can be applied to the future design and evaluation of automotive warnings designed to reduce rear-end collisions.     

Auditory alerts for in-vehicle information systems: the effects of temporal conflict and sound parameters on driver attitudes and performance

In-vehicle information systems will soon confront drivers with an increasing number of warnings and alerts for situations ranging from imminent collisions to the arrival of e-mail messages. Coordinating these alerts can ensure that they enhance rather than degrade driving safety. Two experiments examined how temporal conflict and sound parameters affect driver performance and acceptance. The temporal conflict of an e-mail alert occurring 300 ms before a collision warning interfered with the response to the collision warning, but an e-mail alert occurring 1000 ms before the collision warning had the opposite effect and enhanced the response to the collision warning. These results emphasize the need to consider how in-vehicle devices influence drivers' strategic anticipation of high-demand situations. Regarding sound parameters, results showed that highly urgent sounds tended to speed drivers' accelerator release, but the annoyance associated with highly urgent sounds increased workload. In fact, there was a strong positive association between ratings of annoyance and subjective workload. Consistent with the urgency mapping principle, there was a slight negative association between the differences in the rated urgency of collision warnings and e-mail alerts and subjective workload. The results suggest that warning and alert design should consider an annoyance trade-off in addition to urgency mapping.     

The influence of alarm timing on driver response to collision warning systems following system failure

This driving simulator study focuses on false and missing alarms produced by a forward collision warning system and estimates the effect of alarm timing on driver response to alarm malfunction from the perspective of driver trust in alarms. The results show that drivers who experience late alarms are reluctant to respond to a false alarm and are not influenced by a missed alarm; however, drivers who experience early alarms tend to respond to a false alarm and suffer a delayed response to critical situations when a missing alarm happens. Furthermore, drivers whose judgement of trust is relatively high, tend to exhibit delayed braking, compared with drivers that have lower levels of trust. Driver behaviour towards false and missed alarms may vary according to alarm timing and its influence on trust in alarms; moreover, impaired system effectiveness caused by alarm malfunction may be mitigated by manipulating alarm timing.     

The influence of alarm timing on driver response to collision warning systems following system failure

This driving simulator study focuses on false and missing alarms produced by a forward collision warning system and estimates the effect of alarm timing on driver response to alarm malfunction from the perspective of driver trust in alarms. The results show that drivers who experience late alarms are reluctant to respond to a false alarm and are not influenced by a missed alarm; however, drivers who experience early alarms tend to respond to a false alarm and suffer a delayed response to critical situations when a missing alarm happens. Furthermore, drivers whose judgement of trust is relatively high, tend to exhibit delayed braking, compared with drivers that have lower levels of trust. Driver behaviour towards false and missed alarms may vary according to alarm timing and its influence on trust in alarms; moreover, impaired system effectiveness caused by alarm malfunction may be mitigated by manipulating alarm timing.     

Alarm effectiveness in driver-centred collision-warning systems

The potential use of systems that seek to communicate a warning of impending collision directly to the driver is examined. Technological advances in collisionwarning systems include reliable, low-cost radars, sensors with low noise levels, and the development of accurate detection algorithms for particular crash types, e.g. rearend collisions. However, fundamental practical constraints make perfect sensor detection difficult to achieve. Imperfect detection conflates the false alarm rate and experience with other technologies confirms driver aversion to false warnings. Although sensitive alarm systems with high detection rates and low false alarm rates have been developed, the posterior probability of a collision given an alarm can be quite low because of the low base rate of collision events. As a result, only a small proportion of alarms will represent true collision scenarios. These and other factors can conspire to reduce alarm effectiveness in collision-warning systems. The problem is illustrated analytically and potential solutions are advanced.     

Collision warning timing,driver distraction,and driver response to imminent rear-end collisions in a high-fidelity driving simulator

Rear-end collisions account for almost 30% of automotive crashes. Rear-end collision avoidance systems (RECASs) may offer a promising approach to help drivers avoid these crashes. Two experiments performed using a high-fidelity motion-based driving simulator examined driver responses to evaluate the efficacy of a RECAS. The first experiment showed that early warnings helped distracted drivers react more quickly--and thereby avoid more collisions--than did late warnings or no warnings. Compared with the no-warning condition, an early RECAS warning reduced the number of collisions by 80.7%. Assuming collision severity is proportional to kinetic energy, the early warning reduced collision severity by 96.5%. In contrast, the late warning reduced collisions by 50.0% and the corresponding severity by 87.5%. The second experiment showed that RECAS benefits even undistracted drivers. Analysis of the braking process showed that warnings provide a potential safety benefit by reducing the time required for drivers to release the accelerator. Warnings do not, however, speed application of the brake, increase maximum deceleration, or affect mean deceleration. These results provide the basis for a computational model of driver performance that was used to extrapolate the findings and identify the most promising parameter settings. Potential applications of these results include methods for evaluating collision warning systems, algorithm design guidance, and driver performance model input.     

Lateral control assistance for car drivers: a comparison of motor priming and warning systems

OBJECTIVE: This paper's first objective is to determine whether motor priming assistance (consisting of directional steering wheel vibrations) can be of some benefit compared with more traditional auditory (lateralized sound) or vibratory (symmetric steering wheel oscillation) warning devices. We hypothesize that warning devices favor driving situation diagnosis, whereas motor priming can improve the initiation of action even further. Another objective is to assess the possible benefits of using multimodal information by combining auditory warning with simple steering wheel vibration or motor priming. BACKGROUND: Within the context of active safety devices, the experiment dealt with moderately intrusive driving assistance devices that intervene when a certain level of risk in terms of lane departure is reached. METHOD: An analysis of the steering behavior of 20 participants following episodes of visual occlusion was carried out. Five warning and motor priming devices were compared. RESULTS: All tested devices improved the drivers' steering performance, although their effects were modulated by the drivers' risk assessment. However, performance improvements were found to be greater with a motor priming device. No additional performance enhancement was observed when auditory warning was added to steering wheel vibration or motor priming devices. CONCLUSION: This study confirms the hypothesis that the direct intervention of motor priming at the action level is more effective than a simple warning, which intervenes upstream in situation diagnosis. Multimodal information did not seem to improve driver performance. APPLICATION: This study proposes a new kind of lateral control assistance, which acts at a sensorimotor level, in contrast with traditional warning devices.     

A new class of auditory warning signals for complex systems: auditory icons

This simulator-based study examined conventional auditory warnings (tonal, nonverbal sounds) and auditory icons (representational, nonverbal sounds), alone and in combination with a dash-mounted visual display, to present information about impending collision situations to commercial motor vehicle operators. Brake response times were measured for impending front-to-rear collision scenarios under 6 display configurations, 2 vehicle speeds, and 2 levels of headway. Accident occurrence was measured for impending side collision scenarios under 2 vehicle speeds, 2 levels of visual workload, 2 auditory displays, absence/presence of mirrors, and absence/presence of a dash-mounted iconic visual display. For both front-to-rear and side collision scenarios, auditory icons elicited significantly improved driver performance over conventional auditory warnings. Driver performance improved when collision warning information was presented through multiple modalities. Brake response times were significantly faster for impending front-to-rear collision scenarios using the longer headway condition. The presence of mirrors significantly reduced the number of accidents for impending side collision scenarios. Subjective preference data indicated that participants preferred multimodal displays over single-modality displays. Actual or potential applications for this research include auditory displays and warnings, information presentation, and the development of alternative user interfaces.     

Detection of emergency vehicles: driver responses to advance warning in a driving simulator

OBJECTIVE: This research evaluated the effects of an advance warning device (AWD) on the safety of driver interactions with emergency vehicles (EVs). The AWD was intended to provide drivers with advance warning of an approaching on-call EV via visual and auditory warnings when the EV was within a 300- to 400-m radius. BACKGROUND: Research suggests that drivers can experience difficulty accurately detecting the distance and direction of approaching on-call EV. In-vehicle technology has not previously been explored as a means of overcoming the limitations of existing EV lights and sirens and improving driver detection of EV. METHOD: An experimental study using an advanced driving simulator examined the effects of the AWD on driving performance in a range of circumstances in which real-world EV crashes and near-misses commonly occur. Each event contained a combination of scenario type (adjacent lane, turning across, car following) and warning condition (control, standard, advance). RESULTS: Data from 22 participants were collected, including measures of speed, braking, and visual scanning. For adjacent-lane and turning-across events, the AWD was associated primarily with reductions in mean speed. The AWD resulted in an earlier lane change to clear a path for the EV in the car-following event. CONCLUSION: The reduction in speed observed was a positive finding, given the relationship between impact speed and injury severity. Response priming emerged as the mechanism underpinning these effects. Application: Response priming may result in safety benefits in other settings when an advisory warning is presented before the threat can be perceived.     

Effects of in-vehicle warning information displays with or without spatial compatibility on driving behaviors and response performance

A driving simulator study was conducted to evaluate the effects of five in-vehicle warning information displays upon drivers' emergent response and decision performance. These displays include visual display, auditory displays with and without spatial compatibility, hybrid displays in both visual and auditory format with and without spatial compatibility. Thirty volunteer drivers were recruited to perform various tasks that involved driving, stimulus-response, divided attention and stress rating. Results show that for displays of single-modality, drivers benefited more when coping with visual display of warning information than auditory display with or without spatial compatibility. However, auditory display with spatial compatibility significantly improved drivers' performance in reacting to the divided attention task and making accurate S-R task decision. Drivers' best performance results were obtained for hybrid display with spatial compatibility. Hybrid displays enabled drivers to respond the fastest and achieve the best accuracy in both S-R and divided attention tasks.     

Imperfect in-vehicle collision avoidance warning systems can aid drivers

An experiment was conducted to determine the effects of an in-vehicle collision avoidance warning system (IVCAWS) on driver performance. A driving simulator was driven by 135 licensed drivers. Of these, 120 received alerts from the IVCAWS when their headway to a lead car was less than 2 s, and the other 15 (the control group) received no alerts. Drivers received varied alert interfaces: auditory, visual, and multimodal. The system had varied levels of reliability, determined by both false alarm rate and failure of the IVCAWS to alert to short headway. Results indicated that the IVCAWS led to safer (longer) headway maintenance. High false alarm rates induced drivers to slow down unnecessarily; large numbers of missed alerts did not have any significant impact on drivers. Driver acceptance of the system was mixed. Interface played a role in driver reliance on the system, with the multimodal interfaces generating least reliance. Actual or potential applications of this research include IVCAWS interface selection for greater system efficacy and user acceptance and the advisability of implementation, even of imperfect systems, for drivers who seek to maintain a safer headway.     

Response Times for Auditory and Vibrotactile Directional Cues in Different Immersive Displays

ABSTRACT

Using multisensory signals in advanced driver assistance is continuously increasing as a way to increase the attention and reduce the reaction time. It is essential that driver assistance system is capable of providing directional cues to the driver to direct his attention to the sides of the car as usually the focus is in front of the car. These signals could be for blind spot information, navigation, lane departure warning, collision warning, etc. This study investigated the effect of auditory and vibrotactile on directional attention in driver assistance systems. Moreover, two types of immersive displays were used in the driving simulation, namely the Head Mounted Display (HMD) and CAVE display, to study the effect of the type of display on the human performance. Lane Chang Task was used to assess the attention by measuring the response time to directional information. Vibrotactile and Auditory cues induced equal response times, meanwhile, vibrotactile signal was significantly gained higher satisfaction than auditory.     

Slow eye movement as a possible predictor of reaction delays to auditory warning alarms in a drowsy state

In recently developed intelligent vehicles, warning alarms are often used to prompt avoidance behaviours from drivers facing imminent hazardous situations. However, when critical reaction delays to auditory stimulation are anticipated, the alarm should be activated earlier to compensate for such delays. It was found that reaction times to an auditory stimulus significantly increased in the presence of slow eye movement (SEM), which is known to occur frequently during the wake-sleep transition. The reaction delay could not be attributed to temporal effects such as fatigue and was invariant regardless of response effectors (finger or foot). Moreover, it was found that applied pedal force decreased immediately after an auditory stimulus interrupted SEM. Consequently, it was concluded that SEM can be a good predictor of reaction delays to auditory warning alarms when drivers are in a drowsy state. STATEMENT OF RELEVANCE: The present study demonstrated that simple auditory reaction time significantly increased when SEM emerged. In the design of vehicle safety systems using warning alarms to prompt avoidance behaviours from drivers, such reaction delays during SEM must be taken into account.     

Slow eye movement as a possible predictor of reaction delays to auditory warning alarms in a drowsy state

In recently developed intelligent vehicles, warning alarms are often used to prompt avoidance behaviours from drivers facing imminent hazardous situations. However, when critical reaction delays to auditory stimulation are anticipated, the alarm should be activated earlier to compensate for such delays. It was found that reaction times to an auditory stimulus significantly increased in the presence of slow eye movement (SEM), which is known to occur frequently during the wake–sleep transition. The reaction delay could not be attributed to temporal effects such as fatigue and was invariant regardless of response effectors (finger or foot). Moreover, it was found that applied pedal force decreased immediately after an auditory stimulus interrupted SEM. Consequently, it was concluded that SEM can be a good predictor of reaction delays to auditory warning alarms when drivers are in a drowsy state.

Statement of Relevance:The present study demonstrated that simple auditory reaction time significantly increased when SEM emerged. In the design of vehicle safety systems using warning alarms to prompt avoidance behaviours from drivers, such reaction delays during SEM must be taken into account.     

Alarm timing, trust and driver expectation for forward collision warning systems

In order to improve road safety, automobile manufacturers are now developing Forward Collision Warning Systems (FCWS). However, there has been insufficient consideration of how drivers may respond to FCWS. This driving simulator study focused on alarm timing and its impact on driver response to alarm. The experimental investigation considered driver perception of alarm timings and its influence on trust at three driving speeds (40, 60 and 70 mile/h) and two time headways (1.7 and 2.2 s). The results showed that alarm effectiveness varied in response to driving conditions. Alarm promptness had a greater influence on ratings of trust than improvements in braking performance enabled by the alarm system. Moreover, alarms which were presented after braking actions had been initiated were viewed as late alarms. It is concluded that drivers typically expect alarms to be presented before they initiate braking actions and when this does not happen driver trust in the system is substantially decreased.     

Auditory alerts for in-vehicle information systems: The effects of temporal conflict and sound parameters on driver attitudes and performance

In-vehicle information systems will soon confront drivers with an increasing number of warnings and alerts for situations ranging from imminent collisions to the arrival of e-mail messages. Coordinating these alerts can ensure that they enhance rather than degrade driving safety. Two experiments examined how temporal conflict and sound parameters affect driver performance and acceptance. The temporal conflict of an e-mail alert occurring 300?ms before a collision warning interfered with the response to the collision warning, but an e-mail alert occurring 1000?ms before the collision warning had the opposite effect and enhanced the response to the collision warning. These results emphasize the need to consider how in-vehicle devices influence drivers' strategic anticipation of high-demand situations. Regarding sound parameters, results showed that highly urgent sounds tended to speed drivers' accelerator release, but the annoyance associated with highly urgent sounds increased workload. In fact, there was a strong positive association between ratings of annoyance and subjective workload. Consistent with the urgency mapping principle, there was a slight negative association between the differences in the rated urgency of collision warnings and e-mail alerts and subjective workload. The results suggest that warning and alert design should consider an annoyance trade-off in addition to urgency mapping.