Biomedical subjects

J E Korteling

Publications and source records attributed to J E Korteling.

8 recordsLinked to original sources

PubMed1999

Effects of head-slaved and peripheral displays on lane-keeping performance and spatial orientation.

To improve the efficiency of images presented in low-cost vehicle simulators, the virtual viewing direction (i.e., the direction in which the image is rendered) can be head-slaved, the display can be surrounded with a less detailed peripheral image, or both. Three simulator experiments were used to evaluate the effect of these techniques on lane-keeping performance and spatial orientation. In Experiment 1, vehicle references or a head-slaved display (HSD) provided feedback on the virtual viewing direction. Vehicle references improved lane-keeping performance somewhat with a standard 50 degrees h x 50 degrees v display. An HSD (50 degrees h x 50 degrees v) allowed better steering performance, but not to the levels obtained with a wide display (150 degrees h x 50 degrees v). Experiments 2a and 2b evaluated the effects of surrounding the HSD with a less detailed peripheral image and of moving the HSD discretely or continuously. With the peripheral image, lane-keeping performance (Experiment 2a) and spatial orientation (Experiment 2b) were similar to those with a wide display. In both experiments, performance with the discretely moving HSD was superior to that with the continuously moving HSD. The results show that low-cost driving simulators can be equipped with more efficient displays that are as effective as wide displays for lane-keeping and spatial orientation.

Adult↗

PubMed1998

Continuous haptic information in target tracking from a moving platform.

The present study was conducted to gain insight into the effect of different forms of continuous haptic information (CHI) on operator performance with a moving unmanned platform. In a simulator experiment, participants tracked a moving target with a disturbed viewfinder (moving platform). While the participants performed this combined pursuit and compensatory tracking task, haptic information was provided to them concerning translatory disturbances of the platform. Two steering variables were manipulated between participants: presence or absence of CHI provided at the control device and automated or manual stabilization of the platform. The other factors were image degradation, motor task load, and visual task load. Haptic information was generated by movements of an active joystick that was used for steering the platform. It was shown that both CHI and platform stabilization substantially reduced tracking error. These effects were not additive; CHI improved tracking performance only when the platform was not stabilized, and it did not significantly degrade pursuit tracking performed with a stabilized viewfinder. The magnitude of the CHI effect was independent of image degradation, motor load, and visual load. CHI at the joystick improves tracking performance when it involves relevant control information; when it provides other information, tracking performance is only marginally degraded. Actual or potential applications of this research include performance of missions in environments that are difficult to access, potentially harmful to humans, or both, such as reconnaissance behind enemy lines, tracing of environmental pollution at sea, and assessment of damage in nuclear disaster areas.

Adult↗

PubMed1997

Partial camera automation in an unmanned air vehicle.

The present study focused on an intelligent, semiautonomous, interface for a camera operator of a simulated unmanned air vehicle (UAV). This interface used system "knowledge" concerning UAV motion in order to assist a camera operator in tracking an object moving through the landscape below. The semiautomated system compensated for the translations of the UAV relative to the earth. This compensation was accompanied by the appropriate joystick movements ensuring tactile (haptic) feedback of these system interventions. The operator had to superimpose self-initiated joystick manipulations over these system-initiated joystick motions in order to track the motion of a target (a driving truck) relative to the terrain. Tracking data showed that subjects performed substantially better with the active system. Apparently, the subjects had no difficulty in maintaining control, i.e., "following" the active stick while superimposing self-initiated control movements over the system-interventions. Furthermore, tracking performance with an active interface was clearly superior relative to the passive system. The magnitude of this effect was equal to the effect of update-frequency (2-5 Hz) of the monitor image. The benefits of update frequency enhancement and semiautomated tracking were the greatest under difficult steering conditions. Mental workload scores indicated that, for the difficult tracking-dynamics condition, both semiautomation and update frequency increase resulted in less experienced mental effort. For the easier dynamics this effect was only seen for update frequency.

Adult↗

PubMed1996

Neuropsychological driving fitness tests for brain-damaged subjects.

OBJECTIVES: The study was carried out to evaluate and develop simple tools to assess the driving fitness of brain-damaged patients. DESIGN: Four neuropsychological tests (predictors) were validated against an open-road driving test (criterion standard), which is used by the Department of Adaptations of the Dutch Driving Licensing Agency for assessing disabled drivers. SETTINGS: The predictor tests were conducted in the involved scientific institute; the criterion standard involved participation in normal traffic. PATIENTS: The subject group consisted of 33 men and 5 women who had recovered to a stabilized level from traumatic brain injuries. All had valid driving licenses when they were injured and they were considered to be potentially able to recommence driving. The subjects had a mean reported driving experience of 109.200km (SD = 86.300km). All subjects were recovered from a brain trauma with an average coma duration of 33 days (SD = 51 days). They were tested at least 1 year after the accident. All the subjects had normal or corrected-to-normal vision and none used medications that, according to existing medical criteria, interfere with normal psychomotor or cognitive functioning. Ages at the time of the injury were between 17 and 55 years (mean, 29.8; SD, 10.9). MAIN OUTCOME MEASURES: Pearson product moment correlations (and explained variances) were calculated between the four predictor tests (a Perceptual Speed test, the WAIS Symbol-Digit Substitution subtest, a Tracking-Reaction dual task, and a Time Estimation task) and the open-road criterion standard. RESULTS: The results indicated that performance on both the Perceptual Speed task and the Time Estimation task were significantly correlated with driving performance (p < or = .05). When combined with coma duration and driving experience, the Perceptual Speed and Tracking-Reaction tests together explained 35.3% (r = .59) of the variance in on-road driving performance. CONCLUSIONS: The amount of variance in open-road driving performance that could be accounted for by these tests was insufficient to completely replace an open-road driving fitness assessment. Also, based on other experimental documentation, it is concluded that more integral, domain-specific test (eg, based on driving simulation) need to be developed.

Adolescent↗

PubMed1994

Effects of aging, skill modification, and demand alternation on multiple-task performance.

The magnitude of age effects in single- and dual-tasks may be affected by the degree to which performance depends on well-learned skills that were previously developed. In addition, age-effects may be affected by the requirement to modify these skills and by attentional requirements emerging from the mutual relation of subtasks. Effects of skill modification and emergent attentional processes were examined in an experiment in which experienced subjects performed two perceptual-motor tasks, a vehicle steering task and car-following task in a driving simulator. Car-following was performed under two conditions of familiarity, determining whether or not a normal psychomotor routine had to be modified. In dual-task performance, the demand of subtasks was constant or alternating in counterphase. In general, the older subjects' performance did not differ from that of their younger counterparts, except when the single- or dual-task involved routine modification in car-following. Dual-task costs were basically manifested in the car-following task. Post hoc interpretations of the data indicated that the results were not completely consistent with the complexity hypothesis.

Adult↗

PubMed1993

Effects of age and task similarity on dual-task performance.

When a dual tracking task consisting of two incoherent (uncorrelated) subtasks is partly integrated, such that it is characterized by incompatibility of similarity, or when axis similarity of subtasks is high, it may be difficult to map subtask stimuli to the proper responses. Especially for older adults, an increase in mapping demands may be a source of confusion (cross talk). In the present experiment this issue was addressed with a dual task consisting of two unrelated one-dimensional compensatory tracking tasks with position dynamics. Task performance was measured in terms of root mean square tracking error and cross-axial correlations. Tracking error data were consistent with the hypothesis that older subjects are penalized when there is incompatibility between control and display integration. In general, negative effects of incompatibility of integrality were the greatest when partial integration involved integration of the response component. Both performance measures indicated that with increasing incoherent similarity, task performance of the old subjects was more hampered than was that of their young counterparts.

Adult↗

PubMed1991

Effects of skill integration and perceptual competition on age-related differences in dual-task performance.

Age-related differences in dual-task performance may be affected by factors such as skill integration and perceptual competition. Therefore these factors were examined in a dual-task experiment with young and older adults involving two one-dimensional compensatory tracking tasks. Single-task difficulty was individually adjusted for each subject. It was found that differences in pure dual-task performance between young and older subjects increase when the subtasks are coherent such that skills can be integrated. In addition, the degree to which integration reduces the effects of visual competition was larger for the young than for the older subjects. It is concluded that in dual tasks with coherent subtasks, older adults may show an impaired ability to perform the subtasks in an integrated manner.

Adult↗

PubMed1990

Perception-response speed and driving capabilities of brain-damaged and older drivers.

Three experiments including reaction time (RT) tasks and driving tasks were conducted to identify variables that may be sensitive to the effects of brain damage or aging and to determine how RT tasks relate to driving performance. In Experiment 1 mean RTs of the brain-damaged and older subjects disproportionately increased relative to those of controls, with increasing difference between subsequent compound stimuli. In Experiment 2 response accuracy of brain-damaged subjects deteriorated more than that of controls when the similarity of a task to actual driving increased. In Experiment 3 brain-damaged patients were slower and less accurate than the controls on all measures of a platoon car-following task, whereas the older subjects were only less accurate. Compared with those of the controls, brake RTs of neither the older subjects nor the patients were disproportionately affected by increasing task load. Performance on the platoon driving task could be successfully predicted by a laboratory RT task on time estimation only for the brain-damaged subjects.

Adult↗