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Sight-singing is prevalent in aural skill classes, where learners differ in experience and cognitive abilities. In this research, we investigated whether musical experience, level of study, and working memory capacity (WMC) can predict sight-singing performance and if there is a correlation between WMC and performance among some subgroups of participants. We hypothesized that more experienced students and those with a higher WMC might sight-sing better than those with less experience and lesser WMC. We also hypothesized that the relationship between WMC and sight-singing performance would be more salient for less experienced and less proficient sight-singers. We surveyed 56 subjects about their experience with music, assessed their WMC, and evaluated their performance on a short sight-singing task. The results showed that the age when students began learning music could predict sight-singing performance independently from the number of years of experience and the educational level, suggesting a possible developmental component to sight-singing skill. We also found a negative relationship between WMC and pitch score in the low-performing group and between rhythm and pitch score, suggesting that pitch and rhythm are processed differently. Teachers should be aware of how students’ backgrounds might be related to performance and encourage them to develop strong automated skills, such as reading music or singing basic tonal patterns.

Closed-circuit television (CCTV) is increasingly used as a means to ensure the safety and security of critical infrastructure and public spaces. Operators in control rooms are responsible for monitoring multiple camera feeds that generally exceed the number of screens available. Using a realistic video surveillance simulation, the current study investigates strategies that untrained operators use to deal with this visual overload. The majority of participants adopted a priority strategy by fixating some scenes more than others, as opposed to a parity strategy of devoting roughly equal time across all screens—although participants were largely unaware of the strategy they had used. A parity approach led to better detection performance, perhaps because less time elapsed between viewing each available camera feed thus reducing the probability that an incident could pass unnoticed. The identification of successful scanning strategies can be used to inform operator training.

The failure to notice critical changes in both visual and auditory scenes may have important consequences for performance in complex dynamic environments, especially those related to security, such as aviation, surveillance during major events, and command and control of emergency response. Previous work has shown that a significant number of situation changes remain undetected by operators in such environments. In the current study, we examined the impact of using auditory warning messages to support the detection of critical situation changes and to a broader extent the decision making required by the environment. Twenty-two participants performed a radar operator task involving multiple subtasks while detecting critical task-related events that were cued by a specific type of audio message. Results showed that about 22% of the critical changes remained undetected by participants, a percentage similar to that found in previous work using visual cues to support change detection. However, we found that audio messages tended to bias threat evaluation toward perceiving objects as more threatening than they were in reality. Such findings revealed both benefits and costs associated with using audio messages to support change detection in complex dynamic environments.

Providing decision support to operators in command and control contexts requires careful assessment of its impacts on task performance. Here we describe a human-in-the-loop experiment using a naval air defense testbed to compare three conditions: 1) a baseline interface (DSSBASE; 2) one that displays the temporal proximity of radar aircraft (DSSTEMP); and 3) one which adds a change history panel (DSSCHEX). Threatevaluation accuracy and cognitive models of participants’ judgments did not significantly differ across conditions. Eye-tracking data showed that DSSTEMP lead to a reduced verification of track attributes. Confusion matrices also differed across conditions: DSSTEMP lead to more errors that are “two-categoriesaway” when erroneously classifying hostile aircraft as non-hostile or uncertain. We conclude that in addition to looking at standard metrics of task accuracy and response times, critical insights can be obtained by assessing how different designs for decision support may alter strategies and cognitive processes.

The CSSS microworld simulates the task of a closed-circuit television (CCTV) operator responsible for monitoring multiple CCTV feeds in the context of security surveillance. Operators must manage the display of multiple CCTV feeds, monitor the feeds for critical incidents, and then report detected incidents. The microworld can be used for human factors research, interface design, training and personnel selection, and systems engineering. We present a use case of the CSSS microworld to identify the best predictors of CCTV performance. Our results show that the Automated Operation Span and inattentional blindness tests can predict both CSSS detection rate and false alarms, suggesting that these instruments have the potential for quickly assessing the surveillance competency of candidates. This use case illustrates how the CSSS platform may prove to be useful in the selection of personnel for CCTV operator roles.

Dynamic and complex command and control situations often require the timely recognition of changes in the environment in order to detect potentially malicious actions. Change detection can be challenging within a continually evolving scene, and particularly under multitasking conditions whereby attention is necessarily divided between several subtasks. On-screen tools can assist with detection (e.g., providing a visual record of changes, ensuring that none are overlooked), however, in a high workload environment, this may result in information overload to the detriment of the primary task. One alternative is to exploit the auditory modality as a means to support visual change detection. In the current study, we use a naval air-warfare simulation, and introduce an auditory alarm to coincide with critical visual changes (in aircraft speed/direction) on the radar. We found that participants detected a greater percentage of visual changes and were significantly quicker to detect these changes when they were accompanied by an auditory alarm than when they were not. Furthermore, participants reported that mental demand was lower in the auditory alarm condition, and this was reflected in reduced classification omissions on the primary task. Results are discussed in relation to Wickens’ multiple resource theory of attention and indicate the potential for using the auditory modality to facilitate visual change detection.

Operators working in extreme environments are often confronted with task interruptions. These interruptions tend to impair performance, which can represent a threat to public safety. Most of the tools designed to aid task resumption in such dynamic contexts are post-interruption solutions consisting of providing information about missed events once the interruption is over. The goal of the present study is to test whether a pre-interruption solution consisting of warning operators of an impending interruption can also facilitate interruption recovery. We employed a microworld simulating above-water warfare and compared primary task recovery following an interruption that could either be notified (8 s before it takes place) or not. Results revealed enhanced post-interruption decision accuracy and speed when providing foreknowledge of the imminent interruption. These findings suggest that a pre-interruption warning, which has already proven effective in static contexts, can also support interruption recovery in dynamic settings.

Policy capturing is a judgment analysis method that typically uses linear statistical modeling to estimate expert judgments. A variant to this technique is to capture decision policies using data-mining algorithms designed to handle nonlinear decision rules, missing attributes, and noisy data. In the current study, we tested the effectiveness of a decision-tree induction algorithm and an instance-based classification method for policy capturing in comparison to the standard linear approach. Decision trees are relevant in naturalistic decision-making contexts since they can be used to represent “fast-and-frugal” judgment heuristics, which are well suited to describe human cognition under time pressure. We examined human classification behavior using a simulated naval air defense task in order to empirically compare the C4.5 decision-tree algorithm, the k-nearest neighbors algorithm, and linear regression on their ability to capture individual decision policies. Results show that C4.5 outperformed the other methods in terms of goodness of fit and cross-validation accuracy. Decision-tree models of individuals’ judgment policies actually classified contacts more accurately than their human counterparts, resulting in a threefold reduction in error rates. We conclude that a decision-tree induction algorithm can yield useful models for training and decision support applications, and we discuss the application of judgmental bootstrapping in real time in dynamic environments.

In dynamic environments such as air-traffic control, emergency response and security surveillance, there are severe constraints to information processing and decision-making. Human operators must constantly monitor, assess, and integrate incoming information in order to make optimal decisions in such complex environments. In order to maximize operators’ performance, there is a need for effective technological support for dynamic decision-making. Eye tracking is one promising avenue that can provide online, non-obtrusive indices of cognitive functioning. Using a simulated maritime decision-making environment, we evaluated whether oculometry may be exploited to foretell the decision made by the operator beforehand. Our results showed that pupil dilation and fixation transitions can reveal the upcoming judgment of the human operator by about half a second before the decision. This finding can be useful to design adaptive support tools for dynamic decision-making by integrating the operator’s cognitive state.

Policy capturing is a decision analysis method that typically uses linear statistical modeling to estimate the basis of expert judgments. Using more flexible data mining algorithms may yield more accurate models or instead result in poor functional estimations. The objective of this study is to test the effectiveness of a decision tree induction algorithm for policy capturing in comparison to the standard linear approach. We examined human classification behavior using a simulated naval air-defense task in order to empirically compare the C4.5 decision tree algorithm to linear regression on their ability to capture individual decision policies. The pattern of results shows that C4.5 outperformed linear regression in terms of goodness-of-fit and cross-validation accuracy. Results also show that the decision tree models of individuals’ judgment policies actually classified contacts more accurately than their human counterparts. We conclude that non-linear policy capturing can yield useful models for training and decision support applications.

When the frequency of one harmonic, in a sound composed of many harmonics, is briefly mistuned and then returned to the 'in-tune' frequency and phase, observers report hearing this harmonic as a separate tone long after the brief period of mistuning - a phenomenon called harmonic enhancement. Here, we examined the consequence of harmonic enhancement on listeners' ability to detect a brief amplitude notch embedded in one of the harmonics after the period of mistuning. When present, the notch was either on the enhanced harmonic or on a different harmonic. Detection was better on the enhanced harmonic than on a non-enhanced harmonic. This finding suggests that attention was drawn to the enhanced harmonic (which constituted a new sound object) thereby easing the processing of sound features (i.e., a notch) within that object. This is the first evidence of a functional consequence of the after-effect of transient mistuning on auditory perception. Moreover, the findings provide support for an attention-based explanation of the enhancement phenomenon.

Change blindness (CB) – the failure to notice visual changes – is an important source of human errors in managing dynamic multitasking situations, especially when the tempo at which the situation evolves as well as the timeliness of the decisions are critical to performance and to achieving higher order goals. The support of temporal awareness – in the form of a Temporal Overview Display (TOD) – proved successful in promoting time-based decision heuristics and increasing the timeliness of actions. In the present study, we test the impact on CB of a tool that provides an external time-based representation of the situation and its evolution within an air-warfare simulation that requires participants to perform radar-based subtasks. Although the use of the TOD was previously shown beneficial to performance, the tool may come with a drawback as participants missed a greater number of critical changes compared to a control condition. The TOD is associated with an exacerbation of the attentional source of CB as suggested by a higher percentage of fixated undetected changes. The contextual cues essential to detect a change may not be salient enough to be quickly found in the tool, especially when the operator must deal with time pressure, multitasking and multiple other sources of information. Our study highlights the need for a comprehensive approach to system development and evaluation in order to prevent unintended consequences such as higher CB rates.

International audience; 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.

The LABY microworld, a functional simulation of Air Traffic Control (ATC), captures the underlying processes involved in electronic air traffic management with a simplified version of the operational human-machine interface. LABY is a computer-based human-in-the-loop dynamic environment whereby a controller must issue directional commands to guide aircraft along a predetermined route, while avoiding potential conflicts and dealing concurrently with other incoming information. It can be used for human factors research or system engineering purposes, or configured specifically for use with expert controllers for the training of non-technical skills in ATC. We present a use case of LABY, comparing the efficiency of input devices for ATC: Input times using the mouse were quicker than with the stylus, but error was not greater. We discuss the potential of LABY for system engineering, training and research purposes.

We compared the electrophysiological correlates for the maintenance of non-musical tones sequences in auditory short-term memory (ASTM) to those for the short-term maintenance of sequences of coloured disks held in visual short-term memory (VSTM). The visual stimuli yielded a sustained posterior contralateral negativity (SPCN), suggesting that the maintenance of sequences of coloured stimuli engaged structures similar to those involved in the maintenance of simultaneous visual displays. On the other hand, maintenance of acoustic sequences produced a sustained negativity at fronto-central sites. This component is named the Sustained Anterior Negativity (SAN). The amplitude of the SAN increased with increasing load in ASTM and predicted individual differences in the performance. There was no SAN in a control condition with the same auditory stimuli but no memory task, nor one associated with visual memory. These results suggest that the SAN is an index of brain activity related to the maintenance of representations in ASTM that is distinct from the maintenance of representations in VSTM.

Cardiff University, Cardiff, UK Change detection is required in monitoring and managing complex situations such as air traffic control. Considering that change blindness—the incapacity to detect changes in a visual scene—is a considerable source of human errors and that most studies on change detection have involved static visual scenes, it is crucial to evaluate existing tools designed to help this cognitive function in complex dynamic situations. The goal of the present study was to determine the efficacy of the Change History Explicit (CHEX)—a tool already proven effective when explicit change detection is the only task to execute—when change detection is implicit and intrinsic to a more complex task. Results revealed that the CHEX failed to improve implicit change detection when this task was embedded in a threat-evaluation and weapon-assignment (TEWA) task. Moreover, TEWA performance was hindered and mental workload was perceived as higher when the CHEX was available. Even when the information load imposed by the CHEX was reduced, the tool remained ineffective. This suggests that the nature of the change detection task should be taken into account when designing a decision support system.

The review of literature in sociology and distributed artificial intelligence reveals that the occurrence of conflict is a remarkable precursor to the disruption of multi-agent systems. The study of this concept could be applied to human factors concerns, as man-system conflict appears to provoke perseveration behavior and to degrade attentional abilities with a trend to excessive focus. Once entangled in such conflicts, the human operator will do anything to succeed in his current goal even if it jeopardizes the mission. In order to confirm these findings, an experimental setup, composed of a real unmanned ground vehicle, a ground station is developed. A scenario involving an authority conflict between the partici- pants and the robot is proposed. Analysis of the effects of the conflict on the participants’ cognition and arousal is assessed through heart-rate measurement (reflecting stress level) and eye-tracking techniques (index of attentional focus). Our results clearly show that the occurrence of the conflict leads to perseveration behavior and can induce higher heart rate as well as excessive attentional focus. These results are discussed in terms of task commitment issues and increased arousal. Moreover, our results suggest that individual differences may predict susceptibility to perseveration behavior.

The rate at which technology continues to develop and permeate our lives is such that it has become increasingly easier, and thus more likely, for information to be presented to us via different modalities simultaneously. But to what extent does this confluence of information affect our subsequent judgment and performance? Furthermore, what are the implications for system design when this information is critical to saving our lives and others? This study uses a visual ‘microworld’ simulation of a naval anti-air warfare to investigate whether the content and priority of audio messages that accompany changes in the visual modality assist or hinder performance in the task (identification of change and evaluation of threats). Results indicate that although helping critical change detection, a critical warning in the auditory modality is not as efficient as its visual counterpart. Moreover, audio messages tended to bias threat evaluation towards perceiving objects as more hostile than they were in reality. Such findings have clear implications in regard to the costs and benefits of further exploiting the auditory modality in dynamic visual environments.

We studied the neuronal mechanisms that implement acoustic short-term memory (ASTM) for pitch using event-related potentials (ERP). Experiment 1 isolated an ERP component, the sustained anterior negativity (SAN), that increased in amplitude with increasing memory load in ASTM using stimuli with equal duration at all memory loads. The SAN load effect found in Experiment 1, when pitch had to be remembered to perform the task, was absent in Experiment 2 using the same sounds when memory was not required. In Experiment 3, the memory task was performed without or with concurrent articulatory suppression during the retention interval to prevent rehearsal via an articulatory loop. Load-related effects observed in Experiment 1 were found again, whether participants engaged in concurrent suppression or not. The results suggest that the SAN reflects activity required to maintain pitch objects in an ASTM system that is distinct from articulatory rehearsal.

Omnipresent in everyday multitasking environments task interruptions are usually detrimental to individual performance. Here, we examined whether teaming up renders an individual less vulnerable to interruptions in complex and dynamic situations. We employed a microworld to simulate command and control in a crisis management situation and to examine the relative impact of interruptions on operators working in a functional dyad versus operators working alone. While task interruption was detrimental to efficacy in supervisory control of both single and team interrupted operators, the latter were less vulnerable than the former. However, teaming up did not translate into faster resumption time, a consequence of the overhead attributable to coordination and communication requirements of collaborative work. These findings suggest that in complex and dynamic environments working in a small team confers more resistance to task interruption than working alone and speed of interruption recovery is no guarantee of quality of recovery.

Temporal awareness is key to successful decision making in a wide range of command and control situations, yet little explicit support to maintaining temporal awareness is provided by Decision Support Systems (DSS) for time-critical decisions. In the context of simulated weapon-target scheduling, the present study compared the decision support gained from two display formats: typical geospatial display and temporal display. The results demonstrated that the temporal display facilitates scheduling performance though its beneficial impact seems to require greater familiarization.

Intelligent video surveillance systems (IVSS) that can track people, identify unattended objects, and recognize activity are constantly being developed, updated, and tested against standard test stimuli. The development of these systems, however, seems to focus on technological advancements and largely ignores how automation will affect the human closed-circuit television (CCTV) operator. This paper outlines the advantages of employing a cognitive system engineering approach to the design of IVSS, reviews the literature that has examined human factors issues related to CCTV automation, and introduces a testbed for investigating the effects of automated surveillance technology on human CCTV operators.

Despite advances in surveillance technologies, security and command and control (C2) centers still rely strongly on human operators to detect critical events. Human factors-such as cognitive workload and limited attentional capacity-have been shown to affect operators' ability to detect critical incidents. The current standard surveillance environment comprises a large screen layout that simultaneously displays multiple camera feeds. Although having access to all sources of information at once seems intuitively appealing, there is ample evidence to suggest that it can, in fact, lead to poor detection performance. We propose a design solution that is based on principles grounded in cognitive psychology and user experience design. One key objective is to test empirically whether an atypical design pattern that is consistent with serial cognitive processes induces better performance than the current standard surveillance environment. Three variations of the alternative display pattern will be tested by comparing their effects on detection performance within a surveillance microworld.

The consensus among influential AIDS experts that heterosexual transmission accounts for 90% of HIV infections in African adults emerged no later than 1988. We examine evidence available through 1988, including risk measures associating HIV with sexual behaviour, health care, and socioeconomic variables, HIV in children, and risks for HIV in prostitutes and STD patients. Evidence permits the interpretation that health care exposures caused more HIV than sexual transmission. In general population studies, crude risk measures associate more than half of HIV infections in adults with health care exposures. Early studies did not resolve questions about direction of causation (between injections and HIV) and confound (between injections and STD). Preconceptions about African sexuality and a desire to maintain public trust in health care may have encouraged discounting of evidence. We urge renewed, evidence-based, investigations into the proportion of African HIV from non-sexual exposures.

International audience; This study aims to determine whether indirect touch device can be used to interact with graphical objects displayed on another screen in an air traffic control (ATC) context. The introduction of such a device likely requires an adaptation of the sensory-motor system. The operator has to simultaneously perform movements on the horizontal plane while assessing them on the vertical plane. Thirty-six right-handed participants performed movement training with either constant or variable practice and with or without visual feedback of the displacement of their actions. Participants then performed a test phase without visual feedback. Performance improved in both practice conditions, but accuracy was higher with visual feedback. During the test phase, movement time was longer for those who had practiced with feedback, suggesting an element of dependency. However, this 'cost' of feedback did not extend to movement accuracy. Finally, participants who had received variable training performed better in the test phase, but accuracy was still unsatisfactory. We conclude that continuous visual feedback on the stylus position is necessary if tablets are to be introduced in ATC.

To evaluate the prognosis of HIV-infected patients admitted to ICUs and to identify factors predictive of short- and long-term survival.A prospective study from January 1, 1990, to December 31, 1992, including all consecutive HIV-infected patients admitted to our ICU for the first time. ICU survivors were followed up until January 1, 1994.An 18-bed infectious diseases ICU in a 1,300-bed university hospital in Paris.Four hundred twenty-one HIV-related admissions were recorded during the study period (33.5% of 1,258 admissions to ICU); 354 HIV-infected patients were first ICU admissions and were analyzed.Predictive factors on univariate and multivariate analyses (logistic regression and Cox model) for short- and long-term mortality were performed. Respiratory failure was the main cause of admission (49.2%), followed by neurologic disorders (26.8%), sepsis (10.2%), heart failure (4.5%), and miscellaneous disorders (9.3%). For these groups, in-ICU and in-hospital mortality rates were as follows: 16.7% and 33.9%; 23.2% and 41.1%; 38.9% and 58.3%; 25% and 68.8%; and 12.1% and 24.2%, respectively. In-ICU and in-hospital mortality rates were significantly different across the groups (p=0.026 and 0.002, respectively). Multivariate analysis showed that the in-hospital outcome was significantly associated with functional status (p=0.05), time since AIDS diagnosis (p=0.04), HIV disease stage (0.016), simplified acute physiology score (SAPS I) (p=0.06), need for mechanical ventilation (p0.000001), and its duration (p=0.0001). In the 281 patients who were discharged alive from the ICU, cumulative survival rates were 51%+/-38% at 6 months, 28%+/-38% at 12 months, and 18%+/-30% at 24 months. Median and crude mean+/-SD survival times were 199 days and 316+/-343 days. Multivariate analysis showed that the long-term outcome was significantly associated with functional status (p=0.000001), weight loss (p=0.00001), the CD4 count (p=0.00001), the HIV disease stage (p=0.01), the duration of AIDS (p=0.001), the admission cause group (p=0.03), and the SAPS I at admission (p=0.00001).The short-term (in-ICU and in-hospital) outcome of HIV-infected patients was mainly related to the severity of the acute illness (SAPS I, cause of admission, need for and duration of mechanical ventilation), and to the preadmission health status, based on functional status and weight loss. Some of these parameters, in particular the SAPS I and preadmission health status, also influenced the long-term outcome. Whereas HIV-related variables had little impact on the in-ICU outcome, they were closely related with the in-hospital outcome and even more strikingly with the long-term outcome. Thus, the life expectancy of HIV-infected patients, which depends primarily on the natural history of the HIV infection, is the most powerful determinant of the long-term prognosis. Our results confirm that ICU support for HIV-infected patients should not be considered futile.

Objective: The aim of this study was to test whether inattentional deafness to critical alarms would be observed in a simulated cockpit. Background: The inability of pilots to detect unexpected changes in their auditory environment (e.g., alarms) is a major safety problem in aeronautics. In aviation, the lack of response to alarms is usually not attributed to attentional limitations, but rather to pilots choosing to ignore such warnings due to decision biases, hearing issues, or conscious risk taking. Method: Twenty-eight general aviation pilots performed two landings in a flight simulator. In one scenario an auditory alert was triggered alone, whereas in the other the auditory alert occurred while the pilots dealt with a critical windshear. Results: In the windshear scenario, 11 pilots (39.3%) did not report or react appropriately to the alarm whereas all the pilots perceived the auditory warning in the no-windshear scenario. Also, of those pilots who were first exposed to the no-windshear scenario and detected the alarm, only three suffered from inattentional deafness in the subsequent windshear scenario. Conclusion: These findings establish inattentional deafness as a cognitive phenomenon that is critical for air safety. Pre-exposure to a critical event triggering an auditory alarm can enhance alarm detection when a similar event is encountered subsequently. Application: Case-based learning is a solution to mitigate auditory alarm misperception.

The purpose of this study was to investigate the possibility to integrate a free head motion eye-tracking system as input device in air traffic control (ATC) activity. Sixteen participants used an eye tracker to select targets displayed on a screen as quickly and accurately as possible. We assessed the impact of the presence of visual feedback about gaze position and the method of target selection on selection performance under different difficulty levels induced by variations in target size and target-to-target separation. We tend to consider that the combined use of gaze dwell-time selection and continuous eye-gaze feedback was the best condition as it suits naturally with gaze displacement over the ATC display and free the hands of the controller, despite a small cost in terms of selection speed. In addition, target size had a greater impact on accuracy and selection time than target distance. These findings provide guidelines on possible further implementation of eye tracking in ATC everyday activity.We investigated the possibility to integrate a free head motion eye-tracking system as input device in air traffic control (ATC). We found that the combined use of gaze dwell-time selection and continuous eye-gaze feedback allowed the best performance and that target size had a greater impact on performance than target distance.

This study shows how the use of various measures of eye movement can serve to portray dynamic decision-making (DDM) in a coherent fashion. We extracted eye movement metrics relative to 1) scanpath, 2) eye fixations, and 3) pupillary response, to characterize DDM during the process of risk assessment. Results from Experiment 1 revealed that incorrect classifications were associated with 1) less efficient information search, 2) difficulties in making sense of critical information, and 3) a low level of cognitive load. In Experiment 2, we used eye tracking to assess the impact on DDM of introducing a decision support system. The addition of a temporal-overview display seems to affect processing time in DDM as indexed by shorter scanpaths and fixations during classifications. These findings illustrate how event-based eye movement measures can reveal characteristics and limitations of the ongoing cognitive processing involved in DDM and also contribute to usability testing.

We carried out univariate and multivariate analysis of outcome among 122 patients with prosthetic valve endocarditis (PVE) admitted to our ICU between 1978 and 1992. The predominant pathogens were Staphylococcus aureus (33%), streptococci (20%), coagulase-negative staphylococci (12%), enterococci (10%), and Gram-negative bacilli (9%). At 4 months, overall survival was 66% (42 deaths). Staphylococcus aureus was the main predictor of death (75% vs 15% with other pathogens). In S aureus PVE, multivariate analysis identified the following predictors of death: prothrombin time

Objective: This study examined whether teaming up mitigates individual vulnerability to task interruptions in complex dynamic situations. Background: Omnipresent in everyday multitasking environments, task interruptions are usually detrimental to individual performance. This is particularly crucial in dynamic command and control (C2) safety-critical contexts because of the additional challenge imposed by the continually evolving situation during the interruption. Method: We employed a firefighting microworld to simulate C2 in the context of supervisory control to examine the relative impact of interruptions on participants working in a functional dyad versus operators working alone. Results: Although task interruption was detrimental to participants’ efficacy of monitoring resources, the negative impact of interruption was reduced for those working in teams. Teaming up translated into faster resumption time, but only if both teammates were interrupted simultaneously. Interrupting only one team member was associated with increased postinterruption communications and slower resumption time. Conclusion: These findings suggest that in complex dynamic situations working in a small team confers more resistance to task interruption than working alone by virtue of the reduced individual workload typical of teamwork. The benefit of collaborative work seems nevertheless mediated by the coordination and communication overhead associated with teamwork. Application: The present findings have practical implications for operators dealing with unexpected events such as task interruptions in C2 environments.

In this paper, we report results from a large-scale military experiment with Canadian Forces (CF) officers on the impact of collaborative work support systems—in the present experiment, a set of integrated tools such as operations planning systems, joint fire systems and other logistics tools—on individual and shared situation awareness (SA). In order to measure SA and the ability to share SA, we used the Quantitative Assessment of Situation Awareness (QUASA) technique: We first analyzed SA quality (sensitivity, response bias, accuracy) and metacognition (level of confidence, and calibration bias), and then computed the level of response concordance within and across groups (three different Operational Commands of the CF). The addition of the new support system led to a significant improvement in shared SA. However, this beneficial effect comes with a drop in both objective and perceived individual SA. From this pattern of results, we conclude that there might be a tradeoff between SA sharedness and quality. Supporting the process of sharing SA through enhanced means of information integration and exchange, communication and coordination can also lead to a considerable decrease in individual SA and meta-SA.

The inability of pilots to detect unexpected changes in the environment (e.g., auditory alarms) is a critical problem in aeronautics. The lack of response to alarms is not thought to be a perceptual/attentional issue, but rather that pilots choose to ignore such warnings due to cognitive biases. In the current paper we consider an alternative explanation, by extending the phenomenon of inattentional deafness to aeronautics. Fourteen pilots equipped with an eye tracker and an electrocardiogram performed landings in a flight simulator. During the critical landing, an auditory landing gear alarm was triggered while the volunteers also faced a windshear. Eight out of 14 pilots did not report the occurrence of the critical alarm during the debriefing. Interestingly, all but one of these 'deaf' pilots failed to perform the adequate go-around behavior. These findings establish inattentional deafness as a cognitive phenomenon that is critical for air safety. Keywords: Driver distraction; Language: en

Since the introduction of the concept of auditory scene analysis, there has been a paucity of work focusing on the theoretical explanation of how attention is allocated within a complex auditory scene. Here we examined signal detection in situations that promote either the fusion of tonal elements into a single sound object or the segregation of a mistuned element (i.e., harmonic) that "popped out" as a separate individuated auditory object and yielded the perception of concurrent sound objects. On each trial, participants indicated whether the incoming complex sound contained a brief gap or not. The gap (i.e., signal) was always inserted in the middle of one of the tonal elements. Our findings were consistent with an object-based account in which perception of two simultaneous auditory objects interfered with signal detection. This effect was observed for a wide range of gap durations and was greater when the mistuned harmonic was perceived as a separate object. These results suggest that attention may be initially shared among concurrent sound objects thereby reducing listeners' ability to process acoustic details belonging to a particular sound object. These findings provide new theoretical insight for our understanding of auditory attention and auditory scene analysis.

To describe the presentation and clinical course of septic shock due to Toxoplasma gondii in patients infected with the human immunodeficiency virus (HIV).From April 1988 to February 1992, nine HIV-infected patients were admitted because of predominant septic shock (7 patients) or developed septic shock in the ICU (2 patients). The recent CD4+ cell count ranged from 2 to 84 x 10(6)/L.The main clinical features were (1) a history of fever for longer than 15 days, with a recent increase to more than 39.5 degrees C; (2) a recent history of dyspnea (15 days, 8 cases;7 days, 3 cases); and (3) recent onset of thrombocytopenia (6 of 9 cases). All patients were in shock (hyperkinetic profile in 6 of 7; hypokinetic in 1 of 7), and 8 of 9 were in respiratory distress (ratio of PaO2 over fractional concentration of oxygen in the inspired gas of 117 +/- 23; range, 88 to 155). Chest roentgenograms revealed diffuse alveolar infiltrates in six of nine cases. The serum lactate dehydrogenase (LDH) activity was 6,510 +/- 5,080 IU/L (range, 1,010 to 15,450 IU/L). Serologic tests for T gondii were negative in two cases. Toxoplasma gondii was isolated from lung (9/9), bone marrow (5/7), or blood (2/2). One, 3, and 2 patients had brain, ocular, and myocardial involvement, respectively. No other microbial pathogens were isolated. Seven patients died, 5 less than 3 days after admission.Disseminated toxoplasmosis can cause septic shock in HIV-infected patients. In two cases, the disease was probably a primary infection. The association of high fever, acute dyspnea, recent onset of thrombocytopenia, and a very high level of LDH activity is suggestive of disseminated toxoplasmosis.

Serum concentrations of carcinoembryonic antigen (CEA) were measured in 43 consecutive patients with HIV-related Pneumocystis carinii pneumonia (PCP). The subjects were divided into 2 groups according to the severity of the PCP:PaO2 in ambient air (AA) less than or equal to 50 mmHg on admission (n = 22, group 1) and PaO2 greater than 50 mmHg (n = 21, group 2). In addition, 57 HIV patients with either non-PCP pulmonary diseases (n = 34, group 3) or extrapulmonary disease (n = 23, group 4) were studied. Mean CEA levels (ng/ml) were 13 +/- 10 in group 1 and 4.9 +/- 5.5 in group 2 (p less than 0.001). The corresponding values in groups 3 and 4 were much lower (2.7 +/- 1.8 and 2.4 +/- 1.8, respectively). In group 1, mean initial CEA levels were higher (p less than 0.001) in the patients who died (n = 6; 23.5 +/- 11) than in the survivors (n = 16; 8.9 +/- 7), although the initial mean PaO2 were identical (39 +/- 7 and 39 +/- 8 mmHg, respectively) and the initial mean LDH levels were not significantly different (1544 +/- 530 and 1200 +/- 457 IU/l). CEA levels fell during specific anti-PCP therapy associated with corticosteroids but returned to normal only in the survivors. We conclude that CEA levels are increased in patients with PCP and acute respiratory distress. Among the patients with PaO2 levels of less than or equal to 50 mmHg before treatment, only high levels of CEA (greater than 20 ng/ml) were associated with a fatal outcome, regardless of anti-PCP therapy associated with corticosteroids.(ABSTRACT TRUNCATED AT 250 WORDS)

Mycotic pulmonary aneurysm is an infrequently diagnosed complication of endocarditis. We report here a case of mycotic pulmonary aneurysm and a review of 25 cases from the literature. The mortality rate is greater than 50%. Prompt diagnosis is necessary because early intrasaccular embolization and/or surgical repair is essential to avoid death from rupture of the aneurysm.

In North America Europe and many parts of Asia the ignition of regional epidemics and rapid HIV transmission has been associated principally with the sharing of contaminated injecting equipment and with anal intercourse. Though heterosexual intercourse has been virtually the sole explanation offered for the AIDS epidemic in sub-Saharan Africa to our knowledge in no other part of the world has penile-vaginal exposure (as opposed to “heterosexual sex”) been demonstrated to initiate or sustain rapid HIV propagation. HIV is not transmitted by “sex” but only by specific risky practices. It is not transmitted by “injections” but only by contaminated implements which need to be clearly differentiated as to type and frequency of injection and by the conditions of the exposure setting. In virtually all societies affected by HIV to date both routes seem to play important roles. If we are to understand and intervene in each of these epidemics well-designed studies at both the population and individual levels are urgently needed. It is vital that these be properly controlled for parenteral exposure specific sexual practices and other co-factors and the complex and specific social patterns and networks that accompany them. (excerpt)

We report the first 2 cases of fatal invasive aspergillosis complicating severe malaria. In 2 nonimmune European adults without underlying disease, death was directly ascribable to invasive aspergillosis. We believe that transient malaria-induced immunosuppression allowed massive growth and overwhelming dissemination of preexisting Aspergillus colonization.

Blackwater fever (BWF) is a severe clinical syndrome, characterized by intravascular hemolysis, hemoglobinuria, and acute renal failure that is classically seen in European expatriates chronically exposed to Plasmodium falciparum and irregularly taking quinine. BWF virtually disappeared after 1950, when chloroquine superseded quinine. We report 21 cases of BWF seen in France from 1990 through 1999 in European expatriates who lived in sub-Saharan Africa. All patients had macroscopic hemoglobinuria, jaundice, and anemia. Acute renal failure occurred in 15 patients (71%), 7 of whom required dialysis. The presumed triggers of BWF were halofantrine (38%), quinine (24%), mefloquine (24%), and halofantrine or quinine (14%). Glucose-6-phosphate dehydrogenase (G6PD) activity was normal in the 14 patients who underwent this test. Low-level P. falciparum parasitemia was found in 8 patients. All 21 patients survived. Our data and 13 cases reported in the literature suggest a resurgence of classic BWF among Europeans living in Africa and a need to discuss attendant therapeutic implications.

Clinical and biological pitfalls that lead to incorrect or delayed diagnoses of airport malaria are described based on 7 cases reported from the Paris region in the summer of 1994. We also report the outcome and the epidemiological features of these patients.

To evaluate right ventricle (RV) anatomy and performance and its relationships with pulmonary circulation in AIDS patients.We conducted a prospective blinded study by using cine-MRI, a well-accepted method to assess RV and pulmonary circulation.A university hospital.Ten healthy volunteers and 13 asymptomatic AIDS patients.RV end-diastolic and end-systolic volumes, RV ejection fraction (RVEF), pulmonary artery (PA) diameter, main pulmonary artery distensibility (MPAD), RV free wall diastolic thickness (RVWT), and RV mass were measured. The RVWT/left ventricular wall thickness index was calculated.AIDS patients had significantly increased RV end-diastolic and end-systolic volumes and decreased RVEF (50 +/- 10 vs 59 +/- 6; p0.03). Four AIDS patients had RV wall motion abnormalities; 5 (38%) had an RVEF under 45%. RVWT, the RVWT/left ventricular wall thickness index, and PA diameter were significantly increased in AIDS patients. RV mass was increased in 54% of AIDS patients. MPAD was significantly lower in AIDS patients (18.8 +/- 15 vs 26 +/- 4; p0.01). A significant relationship was found between RV mass and MPAD (r = 0.76; p = 0.02).RV function is frequently impaired in AIDS patients. Anatomic and functional abnormalities found in RV and PA parameters suggest a systolic overload on RV. Pulmonary circulation abnormalities may influence RV structure and function in AIDS patients.

International audience; OBJECTIVE: To determine more precisely the clinical and biological characteristics of AIDS-related cholangitis, and to investigate prognostic variables of this disease. DESIGN: Retrospective clinical and prognostic study. SETTING: Biliary unit, Bicêtre Hospital, France. PATIENTS: HIV-positive patients (n = 52) referred to the unit between December 1986 and June 1993 for biliary symptoms leading to the suspicion of AIDS-related cholangitis, (42 men; 10 women; mean age, 37 +/- 8 years). INTERVENTION: Endoscopic retrograde cholangiopancreatography (ERCP) was performed in order to determine the cause of the biliary symptoms. MAIN OUTCOME MEASURE: Clinical features and evolution of the cholangitis. RESULTS: Among the 52 patients, 45 met the ERCP criteria of AIDS-related cholangitis (36 men; nine women). The diagnosis of cholangitis was strongly suggested by abdominal ultrasonography in 47% of the cases. ERCP showed papillary stenosis, diffuse cholangitis, extrahepatic cholangitis alone, and intrahepatic cholangitis alone in 60, 67, 7 and 27%, respectively. Endoscopic sphincterotomy was performed in 28 patients. Pain was relieved by sphincterotomy in nine patients, but the other clinical or biological features were not influenced. One-year and 2-year survival rates were 41 +/- 7% and 8 +/- 4%, respectively. Multidimensional analysis using a Cox model showed that a lymphocyte count > 500 x 10(6)/l was the only independent predictive factor of better survival. CONCLUSION: AIDS-related cholangitis is a disease which leads preferentially to papillary stenosis or diffuse abnormalities of the biliary tract. Prognostic factors depend on the stage of the HIV infection. Another diagnosis of cholestasis was found in approximately 15% of the patients who showed biliary symptoms.

During a 10-yr period, 40 cases of severe Listeria monocytogenes meningitis were observed. All patients showed consciousness disturbances and 27 of them (68%) focal neurologic signs. Cranial nerve palsies were common (57%). Early general seizures (13 patients) and presence of underlying disease (12 patients) were associated with a high mortality rate. Although the management of antibiotic therapy is open for discussion, chloramphenicol (used in 7 patients) seems to be more effective than other drugs.

Temporal awareness is pivotal to successful real-time dynamic decision making in a wide range of command and control situations; particularly in safety-critical environments. However, little explicit support for operators' temporal awareness is provided by decision support systems (DSS) for time-critical decisions. In the context of functional simulations of naval anti-air warfare and emergency response management, the present study compares operator support provided by two display formats. In both environments, we contrast a baseline condition to a condition in which a temporal display was integrated to the original interface to support operators' temporal awareness. We also wish to establish whether the implementation of time-based DSSs may also come with drawbacks on cognitive functioning and performance.