Biomedical subjects

Christopher D Wickens

Publications and source records attributed to Christopher D Wickens.

16 recordsLinked to original sources

PubMed2007

Effects of conflict alerting system reliability and task difficulty on pilots' conflict detection with cockpit display of traffic information.

A total of 24 pilots viewed dynamic encounters between their own aircraft and an intruder aircraft on a 2-D cockpit display of traffic information (CDTI) and estimated the point and time of closest approach. A three-level alerting system provided a correct categorical estimate of the projected miss distance on 83% of the trials. The remaining 17% of alerts were equally divided between misses and false alarms, of large and small magnitude. Roughly half the pilots depended on automation to improve estimation of miss distance relative to the baseline pilots, who viewed identical trials without the aid of automated alerts. Moreover, they did so more on the more difficult traffic trials resulting in improved performance on the 83% correct automation trials without causing harm on the 17% automation-error trials, compared to the baseline group. The automated alerts appeared to lead pilots to inspect the raw data more closely. While assisting the accurate prediction of miss distance, the automation led to an underestimate of the time remaining until the point of closest approach. The results point to the benefits of even imperfect automation in the strategic alerts characteristic of the CDTI, at least as long as this reliability remains high (above 80%).

Accidents, Aviation↗

PubMed2006

Modeling drivers' visual attention allocation while interacting with in-vehicle technologies.

In 2 experiments, the authors examined how characteristics of a simulated traffic environment and in-vehicle tasks impact driver performance and visual scanning and the extent to which a computational model of visual attention (SEEV model) could predict scanning behavior. In Experiment 1, the authors manipulated task-relevant information bandwidth and task priority. In Experiment 2, the authors examined task bandwidth and complexity, while introducing infrequent traffic hazards. Overall, task priority had a significant impact on scanning; however, the impact of increasing bandwidth was varied, depending on whether the relevant task was supported by focal (e.g., in-vehicle tasks; increased scanning) or ambient vision (e.g., lane keeping; no increase in scanning). The computational model accounted for approximately 95% of the variance in scanning across both experiments.

Adult↗

PubMed2006

Examining the impact of cell phone conversations on driving using meta-analytic techniques.

OBJECTIVE: The performance costs associated with cell phone use while driving were assessed meta-analytically using standardized measures of effect size along five dimensions. BACKGROUND: There have been many studies on the impact of cell phone use on driving, showing some mixed findings. METHODS: Twenty-three studies (contributing 47 analysis entries) met the appropriate conditions for the meta-analysis. The statistical results from each of these studies were converted into effect sizes and combined in the meta-analysis. RESULTS: Overall, there were clear costs to driving performance when drivers were engaged in cell phone conversations. However, subsequent analyses indicated that these costs were borne primarily by reaction time tasks, with far smaller costs associated with tracking (lane-keeping) performance. Hands-free and handheld phones revealed similar patterns of results for both measures of performance. Conversation tasks tended to show greater costs than did information-processing tasks (e.g., word games). There was a similar pattern of results for passenger and remote (cell phone) conversations. Finally, there were some small differences between simulator and field studies, though both exhibited costs in performance for cell phone use. CONCLUSION: We suggest that (a) there are significant costs to driver reactions to external hazards or events associated with cell phone use, (b) hands-free cell phones do not eliminate or substantially reduce these costs, and (c) different research methodologies or performance measures may underestimate these costs. APPLICATION: Potential applications of this research include the assessment of performance costs attributable to different types of cell phones, cell phone conversations, experimental measures, or methodologies.

Automobile Driving↗

PubMed2006

Pilots strategically compensate for display enlargements in surveillance and flight control tasks.

OBJECTIVE: Experiments were conducted to assess the impact of display size on flight control, airspace surveillance, and goal-directed target search. BACKGROUND: Research of 3-D displays has shown that display scale compression influences the perception of flight path deviation, though less is known about the causes that drive this effect. In addition, research on attention-based tasks has shown that information displaced to significant eccentricities can amplify effort, but it is unclear whether the effect generates a performance difference in complex displays. METHOD: In Experiment 1, 16 pilots completed a low-fidelity flight control task under single- and dual-axis control. In Experiment 2, the control task from Experiment 1 was scaled up to a more realistic flight environment, and pilots performed hazard surveillance and target search tasks. RESULTS: For flight control, pilots exhibited less path error and greater stick activity with a large display, which was attributed both to greater enhanced resolution and to the fact that larger depictions of error lead to greater urgency in correcting deviations. Size did not affect hazard surveillance or search, as pilots were adaptive in altering scanning patterns in response to the enlargement of the displays. CONCLUSION: Although pilots were adaptive to display changes in search and surveillance, display size reduction diminished estimates of flight path deviation and control performance because of lowered resolution and control urgency. APPLICATION: Care should be taken when manipulating display size, as size reduction can diminish control performance.

Adult↗

PubMed2006

Automation reliability in unmanned aerial vehicle control: a reliance-compliance model of automation dependence in high workload.

OBJECTIVE: Two experiments were conducted in which participants navigated a simulated unmanned aerial vehicle (UAV) through a series of mission legs while searching for targets and monitoring system parameters. The goal of the study was to highlight the qualitatively different effects of automation false alarms and misses as they relate to operator compliance and reliance, respectively. BACKGROUND: Background data suggest that automation false alarms cause reduced compliance, whereas misses cause reduced reliance. METHOD: In two studies, 32 and 24 participants, including some licensed pilots, performed in-lab UAV simulations that presented the visual world and collected dependent measures. RESULTS: Results indicated that with the low-reliability aids, false alarms correlated with poorer performance in the system failure task, whereas misses correlated with poorer performance in the concurrent tasks. CONCLUSION: Compliance and reliance do appear to be affected by false alarms and misses, respectively, and are relatively independent of each other. APPLICATION: Practical implications are that automated aids must be fairly reliable to provide global benefits and that false alarms and misses have qualitatively different effects on performance.

Aircraft↗

PubMed2006

Age and automation interact to influence performance of a simulated luggage screening task.

INTRODUCTION: An experiment examined the impact of automation on young and old adults' abilities to detect threat objects in a simulated baggage-screening task. METHOD: Younger and older adult participants viewed X-ray images of cluttered baggage, 20% of which contained a hidden knife. Some participants were provided an automated aid with a hit rate of 0.90 and a false alarm rate of 0.25. The aid provided assistance to participants in one of three forms: a text message that appeared before the stimulus image; a text message that appeared following the stimulus image; or a spatial cue concurrent with the stimulus image. Control participants performed the task with no assistance from an aid. RESULTS: Spatial cuing improved performance for both age groups. Text cuing improved young adults' performance, but had no benefit for older participants. Effects were similar whether the text cue preceded or followed the search stimulus itself. DISCUSSION: Results indicate that spatial cuing rather than text alerts may be more effective in aiding performance during a baggage screening task and such benefits are likely to occur regardless of operator age.

Adolescent↗

PubMed2006

Rotation rate and duration effects on the somatogyral illusion.

INTRODUCTION: Aviation spatial disorientation mishaps remain a concern, especially due to their fatality rate. Some of the most insidious disorientations are due to vestibular stimuli in the absence of visual cues. A category of such disorientations are known as somatogyral illusions. METHODS: To determine the effects of spin rate and duration on the perception of the somatogyral illusion, we examined the subjective response of pilots and non-pilots to rotation around the yaw axis in a flight simulator in a manner that would mimic two vestibular illusions found in flight: the washout of the semi-circular canals following sustained turns, and the illusory counter-rotation following return to straight and level flight. There were 29 subjects (14 pilots) who were seated blindfolded in a flight simulator which accelerated to constant plateau rotation rates of 20, 70, and 120 degrees x s(-1) and then decelerated to stationary; plateaus were 10, 20, or 40 s. Subjects reported 1) the time when the perception of rotation ceased (i.e., the subjective time until washout was reached); 2) the relative magnitude of the counter-rotation experienced; and 3) the time until the perception of counter-rotation ceased. Subjects also manipulated a slider to provide a continuous subjective measure of their experience of rotation. RESULTS: The two time measures increased with increases in both the duration and magnitude of the spin. The increase in perceived washout time with spin rate was non-linear (geometric). There was an interaction between spin duration and spin rate on the experience of illusory counter-rotation magnitude such that at low rates, spin duration had no effect, but its effect increased at faster rates. The time constant of adaptation of the semicircular canals was estimated to be 8.3 s. DISCUSSION: The effects were validated against a model of semicircular canal and cupola adaptation, which predicted the data with high accuracy. Pilots and non-pilots did not differ in their illusory experience.

Adaptation, Physiological↗

PubMed2005

Mission control of multiple unmanned aerial vehicles: a workload analysis.

With unmanned aerial vehicles (UAVs), 36 licensed pilots flew both single-UAV and dual-UAV simulated military missions. Pilots were required to navigate each UAV through a series of mission legs in one of the following three conditions: a baseline condition, an auditory autoalert condition, and an autopilot condition. Pilots were responsible for (a) mission completion, (b) target search, and (c) systems monitoring. Results revealed that both the autoalert and the autopilot automation improved overall performance by reducing task interference and alleviating workload. The autoalert system benefited performance both in the automated task and mission completion task, whereas the autopilot system benefited performance in the automated task, the mission completion task, and the target search task. Practical implications for the study include the suggestion that reliable automation can help alleviate task interference and reduce workload, thereby allowing pilots to better handle concurrent tasks during single- and multiple-UAV flight control.

Adolescent↗

PubMed2005

Synthetic vision systems: the effects of guidance symbology, display size, and field of view.

Two experiments conducted in a high-fidelity flight simulator examined the effects of guidance symbology, display size, and geometric field of view (GFOV) within a synthetic vision system (SVS). In Experiment 1, 18 pilots flew highlighted and low-lighted tunnel-in-the-sky displays, as well as a less cluttered follow-me aircraft (FMA), through a series of curved approaches over rugged terrain. The results revealed that both tunnels supported better flight path tracking and lower workload levels than did the FMA because of the availability of more preview information. Increasing tunnel intensity had no benefit on tracking and, in fact, degraded traffic awareness because of clutter and attentional tunneling. In Experiment 2, 24 pilots flew a lowlighted tunnel configured according to different display sizes (small or large) and GFOVs (30 degrees or 60 degrees). Measures of flight path tracking and terrain awareness generally favored the 60 degrees GFOV; however, there were no effects of display size. Actual or potential applications of this research include understanding the impact of SVS properties on flight path tracking, traffic and terrain awareness, workload, and the allocation of attention.

Adult↗

PubMed2004

Visual skills in airport-security screening.

An experiment examined visual performance in a simulated luggage-screening task. Observers participated in five sessions of a task requiring them to search for knives hidden in x-ray images of cluttered bags. Sensitivity and response times improved reliably as a result of practice. Eye movement data revealed that sensitivity increases were produced entirely by changes in observers' ability to recognize target objects, and not by changes in the effectiveness of visual scanning. Moreover, recognition skills were in part stimulus-specific, such that performance was degraded by the introduction of unfamiliar target objects. Implications for screener training are discussed.

Aviation↗

PubMed2004

The role of highlighting in visual search through maps.

Two experiments were conducted in which participants performed a vehicle dispatching task. The intensity of one information source (vehicles in Experiment 1, destinations in Experiment 2) was varied to examine the effects of salience and discrimination on both searching for and processing the information in a cluttered display. Response times were recorded for questions either requiring focused attention on or divided attention between the different information domains in the map. The results of the present experiments indicate that it is possible to declutter a display without erasing any information. By 'lowlighting' one information domain and keeping the other domain at a fairly high intensity level, dividing attention between the information sources is optimal, as is focusing attention on either of the information domains exclusively. These results are discussed in conjunction with a computational model of confusion and salience which serves to predict search and integration performance in a cluttered display with separate domains of information displayed at different intensities.

Attention↗

PubMed2004

Driving and side task performance: the effects of display clutter, separation, and modality.

In-vehicle technologies (IVTs) create additional tasks for the driver. To the extent that these devices degrade driving performance, there will be safety concerns. This study examines the effects of display clutter from overlay, display separation, and modality on driving and IVT task performance. In a fixed-base simulator, 22 drivers drove different routes and responded to infrequent, unexpected road hazards while engaging in a phone number task presented by different displays. Visual displays were located on a head-up (overlaid on the visual horizon or adjacently, just above the vehicle hood) or head-down display (HDD) located near the midconsole. Alternatively, digits were presented auditorily. In general, there were no differences in performance for the adjacent and overlay displays; however, there were costs associated with the HDD and auditory display for some measures. In particular, responses to hazard events were slowed when drivers used the HDD. Overall, the adjacent display best supported performance on all relevant tasks. Potential applications of this research include the design of IVTs with respect to location and modality.

Accidents, Traffic↗

PubMed2003

Attentional models of multitask pilot performance using advanced display technology.

In the first part of the reported research, 12 instrument-rated pilots flew a high-fidelity simulation, in which air traffic control presentation of auditory (voice) information regarding traffic and flight parameters was compared with advanced display technology presentation of equivalent information regarding traffic (cockpit display of traffic information) and flight parameters (data link display). Redundant combinations were also examined while pilots flew the aircraft simulation, monitored for outside traffic, and read back communications messages. The data suggested a modest cost for visual presentation over auditory presentation, a cost mediated by head-down visual scanning, and no benefit for redundant presentation. The effects in Part 1 were modeled by multiple-resource and preemption models of divided attention. In the second part of the research, visual scanning in all conditions was fit by an expected value model of selective attention derived from a previous experiment. This model accounted for 94% of the variance in the scanning data and 90% of the variance in a second validation experiment. Actual or potential applications of this research include guidance on choosing the appropriate modality for presenting in-cockpit information and understanding task strategies induced by introducing new aviation technology.

Adult↗

PubMed2003

Head up versus head down: the costs of imprecision, unreliability, and visual clutter on cue effectiveness for display signaling.

We conducted 2 experiments to investigate the clutter-scan trade-off between the cost of increasing clutter by overlaying complex information onto the forward field of view using a helmet-mounted display (HMD) and the cost of scanning when presenting this information on a handheld display. In the first experiment, this trade-off was examined in terms of the spatial accuracy of target cuing data in a relatively sparse display; in the second, the spatial accuracy of the cue was varied more radically in an information-rich display. Participants were asked to detect and identify targets hidden in the far domain while performing a monitoring task in the near domain using either an HMD or a handheld display. The results revealed that on a sparse display, the reduced scanning from the HMD presentation of cuing out-weighed the costs of clutter for cued targets, regardless of cue precision, but no benefit was found for uncued targets. When the HMD displayed task-irrelevant information, however, target detection was hindered by the extraneous clutter in the forward field of view relative to the handheld display condition, and this cost of clutter increased as the amount of data that needed to be inspected increased. Potential applications of this research include the development of design considerations for head-up displays for aviation and military applications.

Aerospace Medicine↗

PubMed2002

Pilot maneuver choice and workload in free flight.

Two experiments examined pilots' maneuver choice and visual workload in a free-flight simulation. In Experiment 1, 12 pilots flew a high-fidelity flight simulator with a cockpit display of traffic information and maneuvered to avoid traffic in a simulated free-flight environment. Pilots' choices reflected a preference to make vertical rather than lateral avoidance maneuvers and to climb rather than descend. Pilots avoided both complex maneuvers and airspeed maneuvers. The data were modeled in terms of how pilots traded off factors related to safety, efficiency, mental effort, and prior habits. In Experiment 2, 10 pilots flew the same maneuvers as the pilots in Experiment 1 but followed ATC instructions rather than using the CDTI. The CDTI in Experiment 1 occupied 25% of the pilots' visual attention. A comparison of scanning with Experiment 2 suggested that the CDTI pulled visual attention away from the outside world, but this attention diversion did not leave pilots vulnerable to missing traffic not annunciated on the CDTI. Actual or potential applications of the results include understanding the safety implications of presenting traffic displays in the cockpit, and the impact of pilot maneuver preferences on airspace procedures.

Adult↗

PubMedDate not supplied

Effects of battlefield display frames of reference on navigation tasks, spatial judgements, and change detection.

This paper describes an experiment which illustrates the cause of 'cognitive tunnelling' as it affects information gathering and perception-based task performance in computer-generated terrain displays of varying frames of reference. Cognitive tunnelling refers to the effect where observers focus attention on information from specific areas of a display to the exclusion of information presented outside these areas. Previous research suggests that cognitive tunnelling is induced by more immersive or egocentric visual displays. Results from our preceding study suggested that an immersed split-screen display induces cognitive tunnelling and results in poorer information extraction and situation awareness than an exocentric display of the same information. The current study determined that failure of the observers to integrate information across the two views of the immersed display led to the cognitive tunnelling effect. Cognitive tunnelling was also affected by primacy of information initially presented within the larger egocentric view in the immersed display.

Adult↗