Effects of monitoring under high and low taskload on detection of flashing and coloured radar targets

While midair collisions between aircraft are extremely rare occurrences, 'near midair' incidents are more common. The present study sought to evaluate the gains in conspicuity that might be realized if flashing or colour were added as redundant cues to indicate the presence of unexpected, non-tracked aircraft entering controlled airspace, and to examine the extent to which increased taskload and fatigue might influence the expected gains. Sixty-four subjects monitored a simulated air traffic control task over a 2 h period for possible conflict situations (their primary task) under either high or low primary taskload conditions. They also monitored for occasional intrusions by light aircraft identifiable on the basis of target shape alone or with colour and/or flashing added as redundant cues. Flashing as a redundant cue was found to be superior to colour in all aspects tested; unlike colour, detection of flashing targets was unaffected by screen location and by changes in primary taskload. Flashing was also least affected by monitoring fatigue. It was concluded that the superiority of flashing over colour in attracting attention to objects in a display must be weighed against its possible potential for distraction. A practical means of accomplishing this in operational situations is through the use of touch sensitive displays to both acknowledge/confirm target location and to deactivate flashing.     

Eye movement behaviour viewing colour-coded and monochrome avionic displays

Abstract

This paper reports on two experiments in which subjects' eye movement behaviour was monitored while they searched for target information in colour coded and monochrome horizontal situation indicator (HSI) displays. The first experiment required subjects to locate and report alphanumeric information associated with the active waypoint on the displayed flightpath. Initial fixations in the display were more accurately directed to the target information when it was redundantly colour coded compared with when it was coded by shape and relative positional codes. Fewer fixations and a shorter time were required to locate the colour coded target and verbally report the relevant information. The time advantage of colour coded displays compared with monochrome displays was greatest for visually cluttered displays. In the second study there was no advantage of a coloured display when the task was to count all the displayed waypoint symbols on the flight path. The lack of any benefit for colour coding was a result of waypoint symbols having strong positional predictability due to their relationship to the displayed flightpath in both the colour and monochrome displays. The implication from these results is that colour coded information confers an advantage over a spatial code for targets at unknown spatial location but less benefit when target location can be predicted by other visual cues.     

Effectiveness of auditory and tactile crossmodal cues in a dual-task visual and auditory scenario

Abstract

In this study, we examined how spatially informative auditory and tactile cues affected participants’ performance on a visual search task while they simultaneously performed a secondary auditory task. Visual search task performance was assessed via reaction time and accuracy. Tactile and auditory cues provided the approximate location of the visual target within the search display. The inclusion of tactile and auditory cues improved performance in comparison to the no-cue baseline conditions. In comparison to the no-cue conditions, both tactile and auditory cues resulted in faster response times in the visual search only (single task) and visual–auditory (dual-task) conditions. However, the effectiveness of auditory and tactile cueing for visual task accuracy was shown to be dependent on task-type condition. Crossmodal cueing remains a viable strategy for improving task performance without increasing attentional load within a singular sensory modality.

Practitioner Summary: Crossmodal cueing with dual-task performance has not been widely explored, yet has practical applications. We examined the effects of auditory and tactile crossmodal cues on visual search performance, with and without a secondary auditory task. Tactile cues aided visual search accuracy when also engaged in a secondary auditory task, whereas auditory cues did not.     

Interruption management: A comparison of auditory and tactile cues for both alerting and orienting

Tactile and auditory cues have been suggested as methods of interruption management for busy visual environments. The current experiment examined attentional mechanisms by which cues might improve performance. The findings indicate that when interruptive tasks are presented in a spatially diverse task environment, the orienting function of tactile cues is a critical component, which directs attention to the location of the interruption, resulting in superior interruptive task performance. Non-directional tactile cues did not degrade primary task performance, but also did not improve performance on the secondary task. Similar results were found for auditory cues. The results support Posner and Peterson's [1990. The attention system of the human brain. Annual Review of Neuroscience 13, 25–42] theory of independent functional networks of attention, and have practical applications for systems design in work environments that consist of multiple, visual tasks and time-sensitive information.     

Proprioception Variables as Determinants of Lapsed Time Estimation∗

Abstract

It was postulated that increasing positional and force cues would provide more discriminable stimuli to serve as references for the reproduction of a motor response. The levels and mode of the proprioceptive feedback were varied during the coincident positioning task of moving a carriage along a trackway in 2·0 sec. In a balanced design with 80 Ss, 2 values of positional cues, moving the carriage over 2·5 or 65·0 cm, and 2 values of force cues, minimal resistance and 18·9 kg, produced 4 different feedback combinations. Significant learning occurred during 30 trials with knowledge of results (KB), and the combinations involving movement produced the greatest accuracy. Throughout 30 trials without knowledge of results (NoKR) the estimates produced by the movement only and weight only groups became longer, whilst the control group and the movement plus weight group did not drift. It was suggested that the group differences were caused by fatigue.

Interpolated rests of 1 min between groups of 5 trials during the KB condition shortened the first post-rest trial whence performance was restored by the remaining 4 trials. During NoKB the first post-rest trial was again shorter, but since the remaining 4 were overestimated it was more accurate.

In view of these results, apparently redundant movements might aid in timing tasks requiring temporal and spatial organization.     

Computing small-fleet aircraft availabilities including redundancy and spares

Logistics support is a key element of aircraft transportation systems. This paper is concerned with the impact of aircraft spares provisioning decisions on the availability of aircraft. Spares provisioning in this context is complicated by the fact that spares may be shared across aircraft and that aircraft may have redundant systems. In addition, decisions concerning aircraft spares support require a rapid response for safety reasons. Analytical models have proven to provide a quicker response time than corresponding simulation models. There is an existing analytical model that includes the effect of redundancy and spares, but the underlying assumption is that a large number of aircraft are being modeled. In many applications, predictions of the number of times an aircraft can fly each day and the number of aircraft that are ready at any time are applied to a small fleet of aircraft. This paper demonstrates the improvement in computational accuracy that is achieved by reflecting the impact of small numbers of aircraft on availability projections. The approach used is to extend existing finite queuing spares models to including redundancy. Further, the method is used to optimize spares provision with respect to a user specified availability goal. Although the case study for this work is a military combat aircraft application from the Gulf War, the method is applicable to any small system of vehicles or machines where components may be redundant, demand and repairs may be approximated as following an exponential distribution, and limited access to spare parts is the rule.Scope and purposeIn many situations in exploration, mining, rescue, and defense, it is necessary to dispatch a small fleet of machines to a remote area to perform an important function. Since the location is difficult to access, resupply is often difficult or impossible. In anticipation of this situation, the machines often include redundant parts to allow for some component failures in the field that do not eliminate a machine from further use. Decisions have to be made, in advance, as to which backup components (spares) should be included with the machines at the remote site to be used when failures exceed the built-in redundancy level. This turns out to be an interesting modeling problem. Since the number of machines is relatively small, exact counting of machines and their components (both redundant and spares) must be done in order to make a decision. This leads to a combinatorial problem that cannot be solved for practical-sized problems with a reasonable computational effort by, say, discrete simulation. In this paper, we develop a methodology, based on finite queuing theory, which addresses this need. It is applied and validated on an availability situation similar to the deployment of aircraft to the Middle East during the Gulf War.     

The influence of different electronic maps and displays on performance and operator state in a geographic orientation task

Mobile electronic displays for geographic orientation and navigation are used increasingly in various civil and military domains. But it is still unclear which displays and kinds of map presentation suit best for specific purposes. In the present experiment, a head-mounted display (HMD) and a display from a personal digital assistant (PDA) were compared in a simulated geographic orientation task in an urban environment. Furthermore, the effect of three kinds of map presentation (egocentric, geocentric and geocentric with colour cues) was analysed. The simulated orientation task was projected on a screen and participants controlled their locomotion within the urban area by means of a joystick. Task completion time, peripheral attention, workload, fatigue and simulator sickness were registered as dependent variables. In comparison to the geocentric map the egocentric map showed a significant shorter task completion time and the geocentric map with colour cues a significant higher peripheral attention. Task completion time of the HMD and the PDA did not differ significantly. However, peripheral attention and most indices of workload, fatigue and simulator sickness were significantly better for the PDA. Therefore, the results recommend to apply PDAs and egocentric maps for comparable orientation tasks.     

Tactile interruption management: tactile cues as task-switching reminders

Tactile cuing has been suggested as a method of interruption management for busy visual environments. This study examined the effectiveness of tactile cues as an interruption management strategy in a multi-tasking environment. Sixty-four participants completed a continuous aircraft monitoring task with periodic interruptions of a discrete gauge memory task. Participants were randomly assigned to two groups; one group had to remember to monitor for interruptions while the other group received tactile cues indicating an interruption’s arrival and location. As expected, the cued participants evidenced superior performance on both tasks. The results are consistent with the notion that tactile cues transform the resource-intensive, time-based task of remembering to check for interruptions into a simpler, event-based task, where cues assume a portion of the workload, permitting the application of valuable resources to other task demands. This study is discussed in the context of multiple resource theory and has practical implications for systems design in environments consisting of multiple, visual tasks and time-sensitive information.     

Quantitative assessment of effects of visual scanning on concurrent task performance

Much of the research in visual scanning has adopted a single task experimental paradigm. The characteristics of visual scanning in multi-task situations are largely unknown. A quantitative assessment of the effects of visual scanning on concurrent task performance was gained from two experiments. Subjects were required to perform a simulated driving task, which involved a primary pursuit tracking task and a discrete response task. The response task was one of simple information acquisition in the first experiment and of complex information integration in the second. The information acquisition task required subjects to search for a spatial or verbal target. The information integration task required them to search for a spatial or verbal target and then make a rule-based decision by integrating the information carried by current and previous targets. The two types of task involved either spatial or verbal material, whose location was displayed with 4 levels of spatial uncertainty. The results of the two experiments which were: 2 (single/dual task) × 2 (spatial/verbal material) × 4 (levels of uncertainty of target location) revealed unique characteristics of visual scanning in multi-task performance. The effects of visual scanning on task performance and subjective workload were more pronounced in the dual task conditions than in the single. Increases in scanning demand produced greater interference with a concurrent spatial task than with a verbal one when the location uncertainty of visual scanning was sufficiently high. Implications for multi-task human-machine interface design are discussed.     

Attentional costs and failures in air traffic control notifications

Large display screens are common in supervisory tasks, meaning that alerts are often perceived in peripheral vision. Five air traffic control notification designs were evaluated in their ability to capture attention during an ongoing supervisory task, as well as their impact on the primary task. A range of performance measures, eye-tracking and subjective reports showed that colour, even animated, was less effective than movement, and notifications sometimes went unnoticed. Designs that drew attention to the notified aircraft by a pulsating box, concentric circles or the opacity of the background resulted in faster perception and no missed notifications. However, the latter two designs were intrusive and impaired primary task performance, while the simpler animated box captured attention without an overhead cognitive cost. These results highlight the need for a holistic approach to evaluation, achieving a balance between the benefits for one aspect of performance against the potential costs for another.

Practitioner summary: We performed a holistic examination of air traffic control notification designs regarding their ability to capture attention during an ongoing supervisory task. The combination of performance, eye-tracking and subjective measurements demonstrated that the best design achieved a balance between attentional power and the overhead cognitive cost to primary task performance.     

Understanding the human performance envelope using electrophysiological measures from wearable technology

In this article, we capture electrophysiological measures from a new wearable technology to understand the human performance envelope. Using the NASA Multi-Attribute Task Battery (MATB II), participants completed tasks associated with flight control which included communication, tracking and system and resource monitoring. Electrophysiological measures relating to cardiac activity and respiration were taken using the new wearable technology. Our results show significant differences in both heart rate and respiration rate in response to different taskloads and that higher taskloads were associated with higher mental workload. Frequency measures of heart rate variability discriminated different task types but not taskloads. This finding may be related to differences in task complexity being more important than the number events which we have used to manipulate taskload. We suggest that this new generation of wearable sensors could be used to inform operator locus in a human performance envelope, indicating when assistance by the aircraft or another crew member may be necessary to maintain safe and efficient performance.     

The differential effect of vibrotactile and auditory cues on visual spatial attention

Previous research has shown that the presentation of spatially predictive auditory and vibrotactile warning signals can facilitate driver responses to driving events seen through the windscreen or rearview mirror. The present study investigated whether this facilitation reflects the priming of the appropriate response (i.e. braking vs. accelerating) or an attentional cuing effect (i.e. a perceptual benefit that facilitates subsequent behavioural responding). In the experiments reported here, participants had to discriminate the colour of a number plate (red vs. blue) following the presentation of either spatially predictive vibrotactile (experiment 1) or auditory (experiment 2) warning signals that indicated the likely location (front or back) of the visual target, while simultaneously performing a highly attention-demanding rapid serial visual presentation task. Numberplate discrimination performance was facilitated following the presentation of valid auditory cues, but not following the presentation of equally informative vibrotactile cues. The use of an orthogonal spatial cuing design enabled with us to rule out of a potential response priming account of these data. The results suggest that whilst directional congruency between a warning signal and a target event may be sufficient to facilitate performance due to the priming of the appropriate response, attentional facilitation effects may also require the co-location of the cue and target within the same functional region of space.     

The differential effect of vibrotactile and auditory cues on visual spatial attention

Previous research has shown that the presentation of spatially predictive auditory and vibrotactile warning signals can facilitate driver responses to driving events seen through the windscreen or rearview mirror. The present study investigated whether this facilitation reflects the priming of the appropriate response (i.e. braking vs. accelerating) or an attentional cuing effect (i.e. a perceptual benefit that facilitates subsequent behavioural responding). In the experiments reported here, participants had to discriminate the colour of a number plate (red vs. blue) following the presentation of either spatially predictive vibrotactile (experiment 1) or auditory (experiment 2) warning signals that indicated the likely location (front or back) of the visual target, while simultaneously performing a highly attention-demanding rapid serial visual presentation task. Numberplate discrimination performance was facilitated following the presentation of valid auditory cues, but not following the presentation of equally informative vibrotactile cues. The use of an orthogonal spatial cuing design enabled with us to rule out of a potential response priming account of these data. The results suggest that whilst directional congruency between a warning signal and a target event may be sufficient to facilitate performance due to the priming of the appropriate response, attentional facilitation effects may also require the co-location of the cue and target within the same functional region of space.     

Isoresponse time regions for the evaluation of visual search performance in ergonomic interface models.

Computer-aided ergonomic evaluation models often provide a limited function of visual performance, usually in the form of visibility tests at any given location. It is, however, of great importance to complete a visual task in a predetermined time successfully or to predict the time to complete the task, e.g., a task of high-level control such as aircraft flight operations. In this study, isoresponse time regions which have an effect on visual performance in real-life situations are presented as an effort to complement aforementioned shortcomings of ergonomic interface models. A multiple regression was used to provide equal response time regions, being asymmetrical in shape. In addition, the fuzzy linear regression (FLR) model was introduced to provide a fuzzy set from which a decision-maker might select appropriately. It provided similar fitted values with having the advantage of utilizing the interval of those fitted values over the conventional regression model. The results can be applied effectively to the design of an interface for diverse visual tasks in real situations.     

Interruption management: the use of attention-directing tactile cues

Previous research has suggested that providing informative cues about interrupting stimuli aids management of multiple tasks. However, auditory and visual cues can be ineffective in certain situations. The objective of the present study was to explore whether attention-directing tactile cues aid or interfere with performance. A two-group posttest-only randomized experiment was conducted. Sixty-one participants completed a 30-min performance session consisting of aircraft-monitoring and gauge-reading computer tasks. Tactile signals were administered to a treatment group to indicate the arrival and location of interrupting tasks. Control participants had to remember to visually check for the interrupting tasks. Participants in the treatment group responded to more interrupting tasks and responded faster than did control participants. Groups did not differ on error rates for the interrupting tasks, performance of the primary task, or subjective workload perceptions. In the context of the tasks used in the present research, tactile cues allowed participants to effectively direct attention where needed without disrupting ongoing information processing. Tactile cues should be explored in a variety of other visual, interrupt-laden environments. Potential applications exist for aviation, user-interface design, vigilance tasks, and team environments.     

Executive support systems in strategic environmental information processing

Abstract

There has been much research into the feasibility of speech in aircraft cockpits, but little in human supervisory control tasks. Speech displays can provide a number of benefits over conventional, visual displays, particularly as a means of providing alarm information. We discuss the term ‘alarm’, and suggest that different alarm situations will have different information requirements. Thus, a single type of alarm display may not be suitable for the complete range of situations encountered in the control room. We investigated the use of speech for different ‘alarm-initiated actions’: recording, urgency rating, location identification, and action specification. These tasks varied in terms of difficulty, and this affected performance. We also varied the quality of speech, comparing synthesized with human speech. While speech quality affected performance on the recording task, we found that task difficulty interacted with speech quality on the other tasks. This means that definable ‘trade-offs’ exist between the use of speech and the situation in which it is to be used.     

The postural and control-display gain effects of distal pointing on upper extremity fatigue

Pointing at displays from a distance is becoming common in both work and domestic environments. Ray-casting interaction is easy for novices to learn and understand, but this technique can cause physiological fatigue. To address this issue, the present study aims to investigate the issue of fatigue caused by joint-based pointing methods and Control-Display gains (CD gains) via Fitts' task. Ten healthy subjects participated in the experiment and performed multi-directional tapping tests with three joint-based pointing methods and three CD gains. The experimental results indicated that the joint-based pointing methods indeed affected the physiological and subjective fatigue of the upper limb muscles and measured body parts during distal pointing tasks. The wrist-based pointing method, which can induce substantially lower physiological and subjective fatigue, appears to be superior to the other two methods. There were no significant main effects of CD gains on either physiological fatigue or subjective Borg's CR-10 rating.     

Do visual word segmentation cues improve reading performance in Chinese reading？

Abstract

It is controversial whether providing visual word segmentation cues can improve Chinese reading performance. This study investigated this topic by examining how visual word segmentation cues such as grey highlighting, red colour and interword spacing influence global sentence reading and local word recognition during reading Chinese text in three experiments. The results showed that interword spacing could facilitate local word recognition but could not increase reading speed. In contrast, grey highlighting and red colour could improve neither local word recognition nor global sentence reading performance. Instead, these cues increased the number of fixations and saccades, resulting in slower reading speed. These results suggest that even red colour is not a practically visual cue for Chinese word segmentation and the corresponding mechanisms were discussed.

Practitioner Summary: We studied how visual cues such as grey highlighting, red colour and interword spacing influenced Chinese reading performance. Our data showed that even the red colour was not an efficient cue for Chinese word segmentation. The corresponding mechanisms and future direction were discussed regarding how to improve Chinese reading performance.     

Mediating human interaction with video: the fallacy of the talking heads

Given that communication network bandwidth remains at a premium, the design of multiparty mediated systems is a problem of conveying the least redundant information first. We investigated the redundancy of gaze direction in relation to typical full-motion visual cues in performing a triadic abstract office communication task. The results of the experiment indicate that the use of still-video does not necessarily have a negative impact on task performance. Gaze directional cues may provide extra regulative information, but with regard to task performance in small, well-organized groups this information seems to be largely redundant.     

The far-anchor effect: errors in the perception of motion and implications for aviation safety

The far-anchor effect is responsible for a motion-in-depth illusion that has only recently been recognized. When viewing conditions are limited, motions in depth of a farther target in a two-object display may readily be perceived as opposite motions in depth of the nearer target. The present studies determined whether this error could be avoided through controlled fixation or training with feedback. Under conditions of reduced visibility, participants (college students) viewed 64 two-target presentations varying in the position of the moving target and its direction of motion. Neither fixation instructions nor informational feedback about motion errors affected the occurrence of the basic illusion, nor did a vertical separation of the targets eliminate the main effect, indicating the robustness of the motion illusion under some relatively realistic variations. Such errors in judging motion in depth have significance for both midair collisions between aircraft and ground-incursion accidents under conditions of reduced visibility. Potential applications include the elaboration of examples used in pilot training programs or in training programs for ground personnel.