Alerts for in-vehicle information systems: annoyance, urgency, and appropriateness

OBJECTIVE: This study assesses the influence of the auditory characteristics of alerts on perceived urgency and annoyance and whether these perceptions depend on the context in which the alert is received. BACKGROUND: Alert parameters systematically affect perceived urgency, and mapping the urgency of a situation to the perceived urgency of an alert is a useful design consideration. Annoyance associated with environmental noise has been thoroughly studied, but little research has addressed whether alert parameters differentially affect annoyance and urgency. METHOD: Three 2(3) x 3 mixed within/between factorial experiments, with a total of 72 participants, investigated nine alert parameters in three driving contexts. These parameters were formant (similar to harmonic series), pulse duration, interpulse interval, alert onset and offset, burst duty cycle, alert duty cycle, interburst period, and sound type. Imagined collision warning, navigation alert, and E-mail notification scenarios defined the driving context. RESULTS: All parameters influenced both perceived urgency and annoyance (p < .05), with pulse duration, interpulse interval, alert duty cycle, and sound type influencing urgency substantially more than annoyance. There was strong relationship between perceived urgency and rated appropriateness for high-urgency driving scenarios and a strong relationship between annoyance and rated appropriateness for low-urgency driving scenarios. CONCLUSION: Sound parameters differentially affect annoyance and urgency. Also, urgency and annoyance differentially affect perceived appropriateness of warnings. APPLICATION: Annoyance may merit as much attention as urgency in the design of auditory warnings, particularly in systems that alert drivers to relatively low-urgency situations.     

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.     

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.     

Perceived urgency mapping across modalities within a driving context

Hazard mapping is essential to effective driver-vehicle interface (DVI) design. Determining which modality to use for situations of different criticality requires an understanding of the relative impact of signal parameters within each modality on perceptions of urgency and annoyance. Towards this goal we obtained psychometric functions for visual, auditory and tactile interpulse interval (IPI), visual color, signal word, and auditory fundamental frequency on perceptions of urgency, annoyance, and acceptability. Results indicate that manipulation of IPI in the tactile modality, relative to visual and auditory, has greater utility (greater impact on urgency than annoyance). Manipulations of color were generally rated as less annoying and more acceptable than auditory and tactile stimuli; but they were also rated as lower in urgency relative to other modality manipulations. Manipulation of auditory fundamental frequency resulted in high ratings of both urgency and annoyance. Results of the current investigation can be used to guide DVI design and evaluation.     

A psychophysiological evaluation of the perceived urgency of auditory warning signals

One significant concern that pilots have about cockpit auditory warnings is that the signals presently used lack a sense of priority. The relationship between auditory warning sound parameters and perceived urgency is, therefore, an important topic of enquiry in aviation psychology. The present investigation examined the relationship among subjective assessments of urgency, reaction time, and brainwave activity with three auditory warning signals. Subjects performed a tracking task involving automated and manual conditions, and were presented with auditory warnings having various levels of perceived and situational urgency. Subjective assessments revealed that subjects were able to rank warnings on an urgency scale, but rankings were altered after warnings were mapped to a situational urgency scale. Reaction times differed between automated and manual tracking task conditions, and physiological data showed attentional differences in response to perceived and situational warning urgency levels. This study shows that the use of physiological measures sensitive to attention and arousal, in conjunction with behavioural and subjective measures, may lead to the design of auditory warnings that produce a sense of urgency in an operator that matches the urgency of the situation.     

Judging the urgency of non-verbal auditory alarms: a case study

When designed correctly, non-verbal auditory alarms can convey different levels of urgency to the aircrew, and thereby permit the operator to establish the appropriate level of priority to address the alarmed condition. The conveyed level of urgency of five non-verbal auditory alarms presently used in the Canadian Forces CH-146 Griffon helicopter was investigated. Pilots of the CH-146 Griffon helicopter and non-pilots rated the perceived urgency of the signals using a rating scale. The pilots also ranked the urgency of the alarms in a post-experiment questionnaire to reflect their assessment of the actual situation that triggers the alarms. The results of this investigation revealed that participants' ratings of perceived urgency appear to be based on the acoustic properties of the alarms which are known to affect the listener's perceived level of urgency. Although for 28% of the pilots the mapping of perceived urgency to the urgency of their perception of the triggering situation was statistically significant for three of the five alarms, the overall data suggest that the triggering situations are not adequately conveyed by the acoustic parameters inherent in the alarms. The pilots' judgement of the triggering situation was intended as a means of evaluating the reliability of the alerting system. These data will subsequently be discussed with respect to proposed enhancements in alerting systems as it relates to addressing the problem of phase of flight. These results call for more serious consideration of incorporating situational awareness in the design and assignment of auditory alarms in aircraft.     

Judging the urgency of non-verbal auditory alarms: a case study

When designed correctly, non-verbal auditory alarms can convey different levels of urgency to the aircrew, and thereby permit the operator to establish the appropriate level of priority to address the alarmed condition. The conveyed level of urgency of five non-verbal auditory alarms presently used in the Canadian Forces CH-146 Griffon helicopter was investigated. Pilots of the CH-146 Griffon helicopter and non-pilots rated the perceived urgency of the signals using a rating scale. The pilots also ranked the urgency of the alarms in a post-experiment questionnaire to reflect their assessment of the actual situation that triggers the alarms. The results of this investigation revealed that participants' ratings of perceived urgency appear to be based on the acoustic properties of the alarms which are known to affect the listener's perceived level of urgency. Although for 28% of the pilots the mapping of perceived urgency to the urgency of their perception of the triggering situation was statistically significant for three of the five alarms, the overall data suggest that the triggering situations are not adequately conveyed by the acoustic parameters inherent in the alarms. The pilots' judgement of the triggering situation was intended as a means of evaluating the reliability of the alerting system. These data will subsequently be discussed with respect to proposed enhancements in alerting systems as it relates to addressing the problem of phase of flight. These results call for more serious consideration of incorporating situational awareness in the design and assignment of auditory alarms in aircraft.     

The impact of alerting designs on air traffic controller’s eye movement patterns and situation awareness

Abstract

This research investigated controller’ situation awareness by comparing COOPANS’s acoustic alerts with newly designed semantic alerts. The results demonstrate that ATCOs’ visual scan patterns had significant differences between acoustic and semantic designs. ATCOs established different eye movement patterns on fixations number, fixation duration and saccade velocity. Effective decision support systems require human-centered design with effective stimuli to direct ATCO’s attention to critical events. It is necessary to provide ATCOs with specific alerting information to reflect the nature of the critical situation in order to minimise the side effects of startle and inattentional deafness. Consequently, the design of a semantic alert can significantly reduce ATCOs’ response time, therefore providing valuable extra time in a time-limited situation to formulate and execute resolution strategies in critical air safety events. The findings of this research indicate that the context-specified design of semantic alerts could improve ATCO’s situational awareness and significantly reduce response time in the event of Short Term Conflict Alert (STCA) activation which alerts to two aircraft having less than the required lateral or vertical separation.

Practitioner Summary: Eye movements are closely linked with visual attention and can be analysed to explore shifting attention whilst performing monitoring tasks. This research has found that context-specific designed semantic alerts facilitated improved ATCO cognitive processing by integrating visual and auditory resources. Semantic designs have been demonstrated to be superior to acoustic design by directing the operator’s attention more quickly to critical situations.Abbreviations: APW: area proximity warning; ASRS: aviation safety reporting system; ATC: air traffic control; ATCO: air traffic controller; ATM: air traffic management; COOPANS: cooperation between air navigation service providers; HCI: human-computer interaction; IAA: irish aviation authority; MSAW: minimum safe altitude warning; MTCD: medium-term conflict detection; SA: situation awareness; STCA: short term conflict alert; TP: trajectory prediction     

The impact of alerting design on air traffic controllers' response to conflict detection and resolution

Purposes: The research aim is to develop a better design of auditory alerts that can improve air traffic controllers' situation awareness.MethodParticipants are seventy-seven qualified Air Traffic Controllers. The experiment was conducted in the Air Traffic Control operational rooms of the Irish Aviation Authority at Shannon and Dublin. Participants were advised that the trials were in relation to the Operational Air Traffic Control system. ANOVA with two between-subject factors (alerting designs and experience levels) were conducted to analyze the ATCO's response time for three critical events. Bonferroni test was performed for post-hoc analysis on mean differences of response time.ResultsThere is a significant difference in ATCO's response time between acoustic alert and semantic alert across STCA, APW and MSAW. No significant main effect of controllers' experience on ATCO's response time for STCA and APW. Also, there is no significant interaction between alerting design and experience level on ATCO's response time across STCA, APW and MSAW.ConclusionThe results demonstrated that the acoustic alert deployed within the ATM system provides level-1 Situational Awareness to ATCO's compared with an semantic alert which provides not only level-1 of situational awareness for perceived alerts, but also level-2 and level-3 of situational awareness to assist ATCO understanding of critical events and therefore develop more suitable solutions. Consequently, human-centered design of a semantic alert can significantly speed up ATCO's response to STCA, and APW. Furthermore, the semantic alert could alleviate expertise differences by promoting quicker response times for both novice and experienced air traffic controllers.     

On using psychophysical techniques to achieve urgency mapping in auditory warnings

It is well established that warning implementation should aim to achieve urgency mapping between the perceived urgency of the warning itself and the situational urgency of the condition that it indicates. This paper describes how Stevens Power Law [Psychological Review, 64, 153 181, 1957], which quantifies the relationship between objective parameters (such as the pitch of a warning) and subjective parameters (such as perceived urgency), can be applied to the design of auditory warnings to facilitate such urgency mapping. Studies that have quantified and predicted the effects of different warning parameters on perceived urgency using an application of Stevens Power Law are reported.     

Mapping candidate within-vehicle auditory displays to their referents

OBJECTIVE: This study investigated speech, environmental sounds (naturally occurring sounds with arbitrary meanings), auditory icons (natural or synthetic sounds with specific meanings), and abstract synthetic warnings as candidates for within-vehicle interfaces. BACKGROUND: Auditory displays and warnings must satisfy certain criteria, such as being appropriately urgent and commanding appropriately fast response times. However, a semiotic analysis suggests that displays, as signals interpreted by users, should also be mapped successfully onto their referents. METHOD: Response times and accuracy were recorded in a computer task of identifying learned mappings of candidate displays to a range of referent driving events (such as "headway closing"); perceived urgency and pleasantness were assessed separately. RESULTS: Speech and auditory icons produced near-ceiling performance in response times and identification accuracy. Abstract sounds produced notably slower response times and less accuracy. Environmental sounds showed an intermediate pattern of performance for accuracy, but the response times were similar to those of the abstract sounds. Speech utterances were similarly and consistently rated as pleasant but also of intermediate perceived urgency. The three other sound types showed a consistent mapping of their perceived urgency to the situational urgency of their referents; for these sounds, perceived urgency and pleasantness were negatively correlated. CONCLUSION: The results point to the importance of considering the role of signal-referent relationships in designing auditory displays. APPLICATION: The results have applicability for auditory displays in the vehicle interface, whereas the theoretical framework is of value in auditory display design in a broader context.     

Use of auditory icons as emergency warnings: evaluation within a vehicle collision avoidance application.

In the context of emergency warnings, auditory icons, which convey information about system events by analogy with everyday events, have the potential to be understood more quickly and easily than abstract sounds. To test this proposal, an experiment was carried out to evaluate the use of auditory icons for an in-vehicle collision avoidance application. Two icons, the sounds of a car horn and of skidding tyres, were compared with two conventional warnings, a simple tone and a voice saying 'ahead'. Participants sat in an experimental vehicle with a road scene projected ahead, and they were required to brake in response to on-screen collision situations and their accompanying warning sounds. The auditory icons produced significantly faster reaction times than the conventional warnings, but suffered from more inappropriate responses, where drivers reacted with a brake press to a non-collision situation. The findings are explained relative to the perceived urgency and inherent meaning of each sound. It is argued that optimal warnings could be achieved by adjusting certain sound attributes of auditory icons, as part of a structured, user-centred design and evaluation procedure.     

Use of auditory icons as emergency warnings: evaluation within a vehicle collision avoidance application

In the context of emergency warnings, auditory icons, which convey information about system events by analogy with everyday events, have the potential to be understood more quickly and easily than abstract sounds. To test this proposal, an experiment was carried out to evaluate the use of auditory icons for an invehicle collision avoidance application. Two icons, the sounds of a car horn and of skidding tyres, were compared with two conventional warnings, a simple tone and a voice saying ‘ahead’. Participants sat in an experimental vehicle with a road scene projected ahead, and they were required to brake in response to on-screen collision situations and their accompanying warning sounds. The auditory icons produced significantly faster reaction times than the conventional warnings, but suffered from more inappropriate responses, where drivers reacted with a brake press to a non-collision situation. The findings are explained relative to the perceived urgency and inherent meaning of each sound. It is argued that optimal warnings could be achieved by adjusting certain sound attributes of auditory icons, as part of a structured, user-centred design and evaluation procedure.     

Effects of linguistic redundancy and coded voice warnings on system response time

Similar system response times have been reported for keyword and semantic context warning messages based on the premise that the linguistic redundancy of semantic context warnings require less attention than the shorter keyword warnings. The present study was conducted to learn whether an initial word of warning could be used for alerting purposes without increasing system response time and whether or not differences exist between the keyword and semantic conditions. Fifteen subjects were given a flying task using an IBM PC Flight Simulator package and responded to synthesised speech warnings under conditions of cockpit conversation, simulated noise and various flying duties. The keyword-only condition provided a statistically significant lower SRT than all other conditions but, with larger movement/reaction time, appeared to have placed the greatest cognitive demand on subjects. Recommendations are made on the implications regarding the use of the keyword-only format.     

Cough once for danger: icons versus abstract warnings as informative alerts in civil aviation

OBJECTIVE: An experiment investigated the efficacy of auditory icons as warning signals in an aviation context. BACKGROUND: Iconic signals, such as a cough to signal dangerous levels of carbon monoxide, convey information about the nature of an incident and alert the operator that there is a problem, whereas signals that are arbitrarily associated with a critical incident provide relatively less information. Warning recognition speed and accuracy are likely to be influenced by modality of presentation (visual, auditory, auditory + visual) and task demand (low, high). METHODS: The 172 participants completed a computer-based training session and test task that involved responding to abstract or iconic auditory (1 s), visual, or auditory + visual warnings associated with seven critical incidents while performing low- and high-demand concurrent tasks. RESULTS: Significantly fewer training trials were required to learn iconic warnings than abstract warnings. An advantage for iconic warnings persisted into the test phase, evident most consistently as greater warning recognition accuracy. The effect was observed in both high- and low-demand conditions. Auditory abstract warnings, in particular, elicited slow reaction times and poor accuracy. CONCLUSION: Associations between a small number of meaningful environmental sounds and critical incidents can be learned with ease relative to more abstract associations, although training is required and response times are relatively slow. APPLICATION: Sets of distinctive auditory iconic warnings can be designed to alert and inform pilots about non-time-pressured events. Potential applications of language-neutral icons as informative warnings include civil, commercial, and defense aircraft.     

Expert Sources in Warnings May Reduce the Extent of Identity Disclosure in Cyber Contexts

Identity theft is an increasing threat to individuals, institutions, and the economy. People are often not adequately cautious with the disclosure of their personal information in digital contexts and may make poor decisions to reveal private information. Warnings reduce unnecessary information exposure, but the effectiveness may depend on source credibility and expertise on influencing risk perceptions and attitudes. The warnings must be designed for users acting in a digital context. The current research was conducted to determine whether adding a trustworthy and expert source to a message that warned individuals not to disclose their personal information would impact decisions to disclose. First, a survey (pilot study) was conducted to identify the source considered the most trustworthy (among Google, FBI Cyber Division, and Department of Justice) and competent with respect to online security. Google received the highest ratings. In a later experiment, warnings with sources did reduce the extent of disclosure, with the FBI Cyber Division (not Google) being the most effective source. The results indicate that warnings need to be tested with respect to the actual target behavior (in this case, disclosure), rather than relying on individuals’ perceptions of trust, risk, or influence of a warning message when designing effective warnings.     

Noise effect on comfort in open-space offices: development of an assessment questionnaire

It is currently accepted that noise is one of the most important annoyance factors in open-space offices. However, noise levels measured in open spaces of the tertiary sector rarely exceed 65 dB(A). It, therefore, appears necessary to develop a tool that can be used to assess the noise environment of these offices and identify the parameters to be taken into consideration when assessing the noise annoyance. This article presents a questionnaire to be filled by people working in such environment, and a case study in different open plan offices. The majority of the 237 respondents consider that the ambient noise level in their environment is high and that intelligible conversations between their colleagues represent the main source of noise annoyance. This annoyance was significantly correlated with their evaluation of sound intensity, which could not be represented by A-weighted level measurements.     

A cross-cultural comparison of perceived hazard in response to warning components and configurations: US vs. China

There is increasing momentum towards international harmonization of warning standards. Therefore, it is critical to determine the applicability of existing standards across different cultures. Perceived hazard in response to isolated warning components (colors, signal words and symbols) and warning configurations was examined as a function of culture of the product-user (US vs. China) to determine the extent to which ANSI (American National Standards Institute)-recommended components/configurations communicate the expected level of hazard across cultures. 40 college students in the US and 43 in China rated colors, signal words, symbols, and complex configurations on a scale from 1 (not at all hazardous) to 9 (extremely hazardous). US participants consistently provided higher ratings of perceived hazard than Chinese participants. Cross-cultural differences were also observed in the relative levels of perceived hazard assigned to different levels of a label component, particularly in response to colors. However, relative levels of perceived hazard among more complex configurations were similar across culture, even though Chinese participants continued to provide lower absolute ratings of perceived hazard. These results have important implications - if it is assumed that perceived hazard-level must attain some threshold value in order to trigger compliance, then differences in perception could result in a failure of product-users to take appropriate precautions.     

Perceived urgency of and response time to multi-tone and frequency-modulated warning signals in broadband noise

Several pulse parameters that were believed to affect the perceived urgency and response time to auditory warning signals were investigated in a factorial experiment. The independent variables included pulse format (sequential, simultaneous, and frequency-modulated pulses), pulse level (65 and 79dBC), and inter-pulse interval (0, 150 and 300 ms). The applications environments of interest were those having steady-state broadband noise. A probability monitoring task from the Criterion Task Set was used as an operator loading task to impose additional attentional demands during the signal detection and response task. The psychophysical methods of free-modulus magnitude estimation and paired comparison were used to measure subjective perceived urgency. An objective measure of response time to the signal was also obtained. Multivariate statistical analyses indicated that response time decreased significantly as perceived urgency increased. Perceived urgency of the signal increased and response time decreased as pulse level increased. Sequential signals took longer to detect and were rated as less urgent than the other two signal types. Shorter inter-pulse interval was associated with greater perceived signal urgency.     

基于遥感卫星的极端气象观测数据安全预警系统设计

影响极端气象产生与演变的因素众多,给极端气象的预警工作带来较大难度,为及时对极端气象作出有效防御,利用遥感卫星观测数据设计并开发了极端气象观测数据安全预警系统。设计遥感卫星观测数据校准器、观测数据采集器、处理器、安全报警器,调整通信模块的连接方式,完成安全预警系统硬件的优化。通过遥感卫星、暴雨极端天气等数据库表的构建与连接,建立系统数据库。在系统硬件和数据库的支持下,利用遥感卫星观测数据获取气象观测数据,通过气象观测数据特征的提取,估算极端气象参数,将其与设置的安全阈值进行比对,综合极端气象强度和紧迫度系数,实现系统的安全预警功能。实验结果表明,所设计系统的平均预警时间偏差为0.18h,误警率和漏警率平均值分别为2.8%和2.7%,,响应时延平均值为20ms。