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PubMed2001

Visual context and the control of movements through video display.

The aim of this experiment was to test the influence of target context on adaptation to scale perturbations introduced by a video display. Participants performed pointing movements without direct vision of their moving hand, although they could see their movements on a video display. Their perceived movements could be reduced, enlarged. or displayed at their actual size. Three target contexts were compared: dark surround, illuminated frame, and familiar object. Movements were executed with or without vision of hand displacement. Results showed that target context enhanced an allocentric coding of the movement, which improved movement execution. However, the effect of target context changed whether or not the displacement of the hand was available. Overall, the results suggest that target context allowed the extraction of dynamic information about movements, which is used to program and control movements. This suggests that target context could be used efficiently to improve spatial accuracy and speed in teleoperation learning. Potential applications include the reduction of difficulties encountered during teleoperation learning through the introduction of visual context.

Adolescent↗
PubMed2001

The use of 2D and 3D displays for shape-understanding versus relative-position tasks.

Research on when and how to use three-dimensional (3D) perspective views on flat screens for operational tasks such as air traffic control is complex. We propose a functional distinction between tasks: those that require shape understanding versus those that require precise judgments of relative position. The distortions inherent in 3D displays hamper judging relative positions, whereas the integration of dimensions in 3D displays facilitates shape understanding. We confirmed these hypotheses with two initial experiments involving simple block shapes. The shape-understanding tasks were identification or mental rotation. The relative-position tasks were locating shadows and determining directions and distances between objects. We then extended the results to four experiments involving complex natural terrain. We compare our distinction with the integral/separable task distinction of Haskel and Wickens (1993). Applications for this research include displays for air traffic control, geoplots for military command and control, and potentially, any display of 3D information.

Adult↗
PubMed2006

Perceptual issues in the use of head-mounted visual displays.

OBJECTIVE: We provide a review and analysis of much of the published literature on visual perception issues that impact the design and use of head-mounted displays (HMDs). BACKGROUND: Unlike the previous literature on HMDs, this review draws heavily from the basic vision literature in order to help provide insight for future design solutions for HMDs. METHOD: Included in this review are articles and books found cited in other works as well as articles and books obtained from an Internet search. RESULTS: Issues discussed include the effect of brightness and contrast on depth of field, dark focus, dark vergence, and perceptual constancy; the effect of accommodation-vergence synergy on perceptual constancy, eyestrain, and discomfort; the relationship of field of view to the functioning of different visual pathways and the types of visual-motor tasks mediated by them; the relationship of binocular input to visual suppression; and the importance of head movements, head tracking, and display update lag. CONCLUSION: This paper offers a set of recommendations for the design and use of HMDs. APPLICATION: Consideration of the basic vision literature will provide insight for future design solutions for HMDs.

Computer Terminals↗
PubMed1995

Effects of instruction type and boredom proneness in vigilance: implications for boredom and workload.

The present study examined the effects of instruction type and boredom proneness (BP) on vigilance performance, workload, and boredom. Subjects completed the Boredom Proneness Scale and were assigned to high and low groups based on their scores. They then monitored a VDT for critical signals. Half the subjects were instructed to detect "critical" flickers (detection emphasis), and the remaining subjects were instructed to relax but to respond to any flickers observed (relaxation emphasis). Subjects also provided pre- and postvigil ratings of workload, stress, and boredom. A performance decrement was observed for all conditions. Low-BP subjects outperformed high-BP subjects and reported less boredom. Thus the results from the present study provide evidence for the long-sought, elusive link between trait boredom and performance in vigilance. In addition, subjects who received relaxation-emphasis instructions reported lower workload, frustration, and stress for the vigil than did those receiving detection-emphasis instructions. These results are discussed in terms of a recent dynamic model of stress as it relates to sustained attention.

Adolescent↗
PubMed1995

Effect of background scene complexity and field dependence on the legibility of head-up displays for automotive applications.

This study examined the legibility of information presented on head-up displays (HUDs) for automotive application as a function of background scene complexity, the position of the HUD within field of view relative to the background scene, and the perceptual capacity of the perceiver. Groups of field-dependent and field-independent subjects viewed video footage from the perspective of following a lead car on an open road with low, moderate, and high scene complexity. Subjects were required to track the lead vehicle and identify HUD-presented targets of a specified orientation and specified changes in a HUD-presented speedometer. The results indicate that (a) HUD legibility deteriorated with increased visual complexity of the background scene; (b) positioning the HUD on the roadway reduced the effect of background scene complexity on HUD legibility; and (c) field-dependent subjects made fewer correct and more false positive target identifications than did field-independent subjects.

Adolescent↗
PubMed1995

Social and cognitive processes in interpersonal communication: implications for advanced telecommunications technologies.

Interactive multimedia conferencing systems, in which two or more remotely located people can work on cooperative tasks through shared audio, video, and data, appear to be the wave of the future. However, because of great advances in the underlying technology of multimedia conferencing systems, many design decisions have been driven by what is technically feasible as opposed to what will best suit the needs of the users. In this paper we provide a framework for the design and evaluation of features in advanced telecommunications products and services which is derived from empirical research on interpersonal communication. We also discuss implications of this research for the development and use of advanced telecommunications technologies.

Cognition↗
PubMed1995

Telepresence in videocommunications: a study on stereoscopy and individual eye contact.

We conducted two experiments to investigate how stereoscopy and technologies that allow individual eye contact affect the impression of telepresence in video-conferencing. Telepresence is defined as the degree to which participants of a telemeeting get the impression of sharing space with the remote site. Results revealed, among other things, that stereoscopy increases telepresence and makes videoconferencing more attractive. In addition, we found that reduced eye contact angles enhance the recognizability of individually addressed nonverbal signals. However, a setup that eliminates horizontal and vertical eye contact angles seems to be advantageous only in conferences with more than two persons per site.

Computer Terminals↗
PubMed1995

Effects of a laser-induced temporary scotoma on target acquisition performance.

Lasers commonly used in industry and the military are increasingly being recognized as possible hazards to vision and visually guided tasks. This study examined the effects of laser-induced visual loss on target acquisition performance. An argon laser was used to produce a temporary central scotoma. Observers searched for variable-contrast aircraft that were embedded in backgrounds of differing complexity. The laser exposures increased acquisition times 2 to 12 times over baseline levels, indicating that the degree of visual deficit was task dependent. Acquisition time increased as background complexity increased and target contrast decreased. However, target motion facilitated acquisition performance and mitigated the laser effect. Although contrast had a systematic effect on acquisition performance, it was clear that factors other than contrast contributed to target visibility. Other factors that may have affected visibility included distractors and masking effects introduced by the structured backgrounds.

Adaptation, Physiological↗
PubMed1998

A comparison of seven visual fatigue assessment techniques in three data-acquisition VDT tasks.

We compared 7 methods of measuring visual fatigue--accommodation power, visual acuity, pupil diameter, critical fusion frequency (CFF), eye movement velocity, subjective rating of visual fatigue, and task performance--for their sensitivity to visual load. In the experiment, 10 participants performed a monitoring task at 2 viewing distances, read articles under 2 levels of screen contrast, and tracked visual targets at 2 different speeds. The same measurement techniques, excluding pupil diameter and eye movement velocity, were compared by extending the task time from 20 to 60 min with the same VDT tasks to test for possible improvement in sensitivity. The results indicated that sensitivities of accommodation power, visual acuity, and CFF were greatly improved by a longer task period, but these 3 measurement techniques did not distinguish among tasks. Pupil diameter, eye movement velocity, and subjective rating of visual fatigue were sensitive in differentiating tracking from reading and monitoring tasks. Eye movement velocity and subjective rating were sensitive to the changes in target velocity of the tracking task. Although task performance was not directly comparable to other measurement techniques, it helped to ensure that participants maintained the same performance level by devoting more resources to the high-load conditions. Actual or potential applications of this research include using some of these assessment techniques for the design of adaptive displays.

Accommodation, Ocular↗
PubMed1998

Effects of display resolution on visual performance.

The role of display resolution in visual information processing was investigated in 2 experiments. Experiment 1 examined the effects of 2 CRT conditions (resolutions of 60 and 120 dots per inch [dpi]) and a paper control condition (255 dpi) on proofreading speed and accuracy. The results showed that reading performance was significantly better in the paper condition than in the 2 CRT conditions. Experiment 2 examined the effects of 3 different CRT resolutions (62, 69, and 89 dpi) on eye movement parameters (fixation duration and number of fixations) in a visual search task. Further, search reaction times (RTs) and observers' ratings of visual fatigue were analyzed. RTs and fixation durations were significantly increased in the low-resolution condition (62 dpi) as compared with the high-resolution condition (89 dpi). The significant interaction between display resolution and time both for search RTs and fixation durations was taken as evidence for stronger fatigue in the low-resolution conditions. Additionally, the extent of visual fatigue correlates both with search RTs and eye movement parameters. This finding gives rise to the assumption that observers' responsiveness to effects of display resolution in terms of visual fatigue differs markedly. Actual or potential applications of this research include recommendations for the use of high-resolution displays (90 dpi and greater) to optimize visual performance, to make prolonged on-screen viewing more comfortable, and to avoid visual fatigue.

Asthenopia↗
PubMed1999

Effects of cueing and knowledge of results on workload and boredom in sustained attention.

Two models of recently reported high workload associated with vigilance tasks are the direct-cost and indirect-cost views. The former attributes high workload to the need for continuous observation in discriminating signals from neutral events; the latter attributes it to efforts to combat the boredom associated with monotonous vigilance tasks. These opposing views were tested by providing observers with reliable cueing, which rendered observation necessary only when low-probability critical signals were imminent, or with knowledge of results (KR) regarding performance efficiency. On the basis of cue and KR differences in elicited observation activity and motivational value, the direct-cost model led to the anticipation that cueing would result in a high-boredom, low-workload profile and a greater reduction in workload than KR. The indirect-cost model led to the prediction that cueing would result in a high-boredom, high-workload profile and a lesser reduction in workload than KR. The results clearly supported the direct-cost view that the workload of vigilance is task-induced. Consequently, efforts to combat high workload in complex automated systems requiring substantial monitoring by operators should focus specifically upon task-related determinants.

Acoustic Stimulation↗
PubMed2003

Bimodal displays improve speech comprehension in environments with multiple speakers.

Attending to a single voice when multiple voices are present is a challenging but common occurrence. An experiment was conducted to determine (a) whether presenting a video display of the target speaker aided speech comprehension in an environment with competing voices, and (b) whether the "ventriloquism effect" could be used to enhance comprehension, as found by Driver (1996), using ecologically valid stimuli. Participants listened for target words from videos of an actress reading while simultaneously ignoring the voices of 2 to 4 different actresses. Target-word detection declined as participants had to ignore more distracting voices; however, this decline was reduced when a video display of the target speaker was provided. Neither a signal-detection analysis of performance data nor a gaze-contingent analysis revealed a ventriloquism effect. Providing a video display of a speaker when competing voices are present improves comprehension, but obtaining the ventriloquism effect appears elusive in naturalistic circumstances. Actual or potential applications of this research include those circumstances in which a listener must filter a relevant stream of speech from among multiple, competing voices, such as air traffic control and military environments.

Adolescent↗
PubMed1991

[Changes in visual acuity observed in VDT workers in a printing company].

A yearly ophthalmological examination was carried out in 2 VDT worker groups (A-1 and B-1 groups) and 2 control groups (A-2 and B-2 groups). The 4 groups were as follows; workers routinely engaged in both VDT work and key-punch work at a printing company (A-1 group), researchers or office workers handling VDT irregularly at a chemical company (B-1 group), typesetters at a printing company (A-2 group), and office workers at a chemical company (B-2 group). The examination was commenced in the same year in which the workers of A-1 or B-1 group were introduced to VDT work and was carried out for 3 years. Comparison between the first and the last examination on subjective refractive power showed that all the groups had lower refractive powers in the last examination than the first one. The decrease in A-2 group showed the greatest decrease in refractive power among the 4 groups. The decrease in A-2 group was more severe than in the other 2 groups. Before VDT introduction, the workers of A-1 group had been engaged only in key-punch work. Information on naked visual acuities of A-1 group 3 years before VDT introduction was also obtained and compared with those in the first and the last examination. The ratio of workers with a severe reduction in visual acuity evidently increased after VDT introduction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2002

[Stress management for office workers].

The environment which surrounds office workers has undergone a big transformation with the collapse of lifetime employment, the shift from the long employment principle to meritocracy, the results principle, the introduction of flexible work hours, outsourcing and dispatch work. Today's office worker stressor include 1. VDT work, 2. meritocracy, 3. management by objective, 4. excessive load on the middle and advanced age generations, 5. the collapse of the lifetime employment system and 6. non-employee changes. (1) VDT work management, (2) the use of Information technology, (3) Improvement of office environments, (4) Management of long overtime work and (5) Support of superiors and colleagues are thought as stress management.

Access to Information↗
PubMed2000

[Actual conditions of occupational health administration of small-scale enterprises in Japan: (II). Occupational health controls for hazardous and musculo-skeletally stressful working factors].

In order to clarify the actual condition of occupational health management for hazardous and musculo-skeletally stressful work factors in small-scale enterprises (SSEs) in Japan, a questionnaire survey was conducted in an area near Osaka city. The hazardous work factors examined were dust, organic solvents, lead, specified chemical substances, anoxia, noise, hand-arm vibration, ionizing radiation, high and low temperatures, and high air pressure. The musculo-skeletally stressful work factors examined were VDT work, prolonged standing, unnatural postures, handling of heavy weights, and stress on neck, shoulders and arms. The number of SSEs that replied to the questionnaire was 765 (recovery rate: 69.3%). Enterprises with noise, dust, hand-arm vibration and organic solvents numbered 14.0%, 10.7%, 6.9% and 6.4%, respectively, and those with other hazardous factors numbered less than 3%. Special medical examinations and working environment measurements for hazardous factors were conducted in 0.0% to 26.7% and 0.0% to 13.3%, respectively, of the enterprises. Working environment controls were conducted in 0.0% to 40.2%. Enterprises with prolonged standing and VDT work, were 42.0% and 35.8%, whereas those with other stressful factors were approximately 30%. Special medical examinations for musculo-skeletally stressful factors were conducted in 3.0% to 5.1% of the enterprises, and work controls were conducted in 20.4% to 25.3%. Non execution of the special medical examinations and working environment measurements were mainly due to "lack of knowledge of the law (19.7% and 30.2%)" and "lack of time to perform (16.0% and 23.3%)". Non execution of the controls for the hazardous work factors was due to "lack of knowledge as to how to control (9.0%)", "high costs (7.4%)", "lack of time to perform (6.4%)" and "absence of a suitable adviser (5.9%)". Non execution of the controls for stressful work factors was due to "lack of knowledge as to how to control (15.6%)" and "lack of time to perform (10.2%)". Consequently, as a result of the survey, it was suggested that it is necessary to enlighten the employers of SEEs as to the importance of occupational health controls. It is also necessary to propose low-cost, feasible control methods.

Computer Terminals↗
PubMed2002

Impact of telemedicine on the practice of pediatric cardiology in community hospitals.

BACKGROUND: Tele-echocardiography has the potential to bring real-time diagnoses to neonatal facilities without in-house pediatric cardiologists. Many neonates in rural areas, smaller cities, and community hospitals do not have immediate access to pediatric sonographers or echocardiogram interpretation by pediatric cardiologists. This can result in suboptimal echocardiogram quality, delay in initiation of medical intervention, unnecessary patient transport, and increased medical expenditures. Telemedicine has been used with increased frequency to improve efficiency of pediatric cardiology care in hospitals that are not served by pediatric cardiologists. Initial reports suggest that telecardiology is accurate, improves patient care, is cost-effective, enhances echocardiogram quality, and prevents unnecessary transports of neonates in locations that are not served by pediatric cardiologists. OBJECTIVE: We report the largest series to evaluate the impact of telemedicine on delivery of pediatric cardiac care in community hospitals. We hypothesized that live telemedicine guidance and interpretation of neonatal echocardiograms from community hospitals is accurate, improves patient care, enhances sonographer proficiency, allows for more efficient physician time management, increases patient referrals, and does not result in increased utilization of echocardiography. METHODS: Using desktop videoconferencing computers, pediatric cardiologists guided and interpreted pediatric echocardiograms from 2 community hospital nurseries 15 miles from a tertiary care center. Studies were transmitted in real-time using the H.320 videoconferencing protocol over 3 integrated services digital network lines (384 kilobits per second). This resulted in a frame rate of 23 to 30 frames per second. Sonographers who primarily scanned adult patients but had received additional training in echocardiography of infants performed the echocardiograms. Additional views were suggested as deemed necessary by the interpreting physician, and interpretations were made during the videoconference. The results of the echocardiogram and recommendations for patient care were communicated to the referring physician over the telemedicine system. Analyses of accuracy, patient treatment, echocardiogram quality, time to diagnosis, pediatric cardiologist practice time management, patient referral patterns, and echocardiography utilization were conducted prospectively. RESULTS: A total of 500 studies in 364 patients were transmitted during a 30-month period. The most common indication for echocardiography was to rule out congenital heart disease (208 of 500 studies). Signs and symptoms that prompted this concern included cyanosis, murmur, tachypnea, genetic syndrome, arrhythmia, abnormal fetal echocardiogram, and maternal diabetes. Other indications included suspected patent ductus arteriosus (PDA; 182 of 500 studies), intracardiac clot or catheter position, persistent pulmonary hypertension, and hemodynamic instability. Cardiac diagnoses included complex congenital heart disease (n = 16), noncritical heart disease (n = 107), and PDA (n = 86). Additional diagnoses included persistent pulmonary hypertension (n = 12), septal hypertrophy (n = 18), right atrial mass/clot/vegetation (n = 11), and decreased cardiac function (n = 6). An umbilical venous catheter was visualized in the left atrium in 9% (45 of 500) of all studies. No significant abnormalities were found in 244 studies. Major diagnoses were confirmed by subsequent review of videotape in all studies. Comparison of final videotape interpretation to initial telemedicine diagnosis resulted in 1 minor diagnostic change (membranous versus inlet ventricular septal defect). Echocardiograms were performed in subsequent visits in 264 patients. The diagnosis was altered in 3 patients. Telemedicine had an immediate impact on patient care in 151 transmissions. The most common interventions were indomethacin treatment for PDA (n = 76), retraction of umbilical venous catheters from the left atrium (n = 45), inotropic or anticongestive therapy (n = 19), anticoagulation (n = 8), and prostaglandin infusion (n = 8). Nineteen patients were transported to our hospital because of the telemedicine diagnosis. Inpatient or outpatient cardiology follow-up was recommended in an additional 131 studies and did not result in any change in the initial management. The most common diagnoses in these patients were ventricular septal defect (n = 56), atrial septal defect (n = 21), septal hypertrophy (n = 9), intracardiac thrombosis (n = 8), and pulmonary valve stenosis (n = 4). We speculate that the immediate availability of an echocardiographic diagnosis likely prevented unnecessary transport in 14 cases. Recommendations for additional views or adjustment of echocardiography machine settings were made in 95% of transmissions. Real-time guidance was especially helpful in suprasternal notch and subcostal sagittal imaging. Depth, color Doppler sector size, and color Doppler scale were frequently adjusted from routine adult settings during the teleconference. The average time from request for echocardiogram to completion of the videoconference was 28 +/- 14 minutes. This was significantly shorter than the waiting time (12 +/- 16 hours) for the videotape to be delivered by courier. Telemedicine eliminated the need for consultation in 194 cases and allowed the cardiologist to delay the visit until the end of the day in an additional 26 cases. This resulted in average time savings of 4.2 person-hours/wk based on travel and consultation time. Utilization of echocardiography was similar before (35 of 1000 births) and after (33 of 1000 to 43 of 1000) telemedicine installation. The percentage of neonatal echocardiograms that were interpreted by our practice increased from 63% to 81% at 1 hospital and from 0% to 100% at the other hospital. CONCLUSION: Real-time transmission of neonatal echocardiograms from community hospitals over 3 integrated services digital network lines is accurate and has the potential to improve patient care, enhance echocardiogram quality, aid sonographer education, and have a positive impact on referral patterns and time management without increasing the utilization of echocardiography.

Cardiology Service, Hospital↗
PubMed2002

[Chromosome abnormalities caused by computer video display monitors' radiation].

OBJECTIVE: Concerns were raised about the potential damaging effects of electromagnetic field (EMF) radiation emissions of ELF (extremely low frequency) and VLF (very low frequency) computer video display monitors (VDM), it was assessed the frequency of structural chromosome abnormalities and investigated the cell cycle kinetics in individuals occupationally exposed to VDM radiation. METHODS: Chromosome aberrations were investigated in 2,000 first cell cycle metaphases obtained after 48-hour cultures of peripheral blood lymphocytes drawn from 10 individuals occupationally exposed to VDM radiation (group E) and 10 controls (group C). Cell cycle kinetics was studied using the mitotic index (MI) and cellular proliferation index (CPI). RESULTS: Statistical analysis showed significantly higher frequencies of anomalous metaphases (E=5.9%; C=3.7%) and anomaly/cell (E=0.066+/-0.026; C= 0.040+/-0.026) in individuals exposed to VDM radiation. The most common cytogenetic alterations seen were chromatid breaks at frequencies of 0.034+/-0.016 in group E and 0.016+/-0.015 in group C. There was no significant difference between MI and CPI frequencies in both groups. CONCLUSIONS: The study findings suggest genotoxic effects of EMF emissions revealed by the higher frequency of chromatid breaks in individuals exposed to VDM radiation. However, there is a need of further studies on EMF genetic effects using other investigation methods.

Adult↗
PubMed2002

Endoscopic visualization of the submarginal gingiva dental sulcus and tooth root surfaces.

BACKGROUND: Direct, real-time visualization of the hard and soft tissues within the gingival sulcus may aid the clinician in diagnosis and therapy of periodontal disease. This report describes an endoscope specifically designed for this purpose and the interpretation of dental endoscopic images. METHODS: Medical endoscope technology was modified for application in the dental environment. A fixed, fused fiber optic bundle, less than 1 millimeter in diameter, was coupled to an active matrix LCD-TFT flat panel video monitor for viewing by the clinician. A bilumen sheath was designed to provide irrigation of the sulcus and a sterile barrier between the patient and the fiber bundle. Standard dental curets and ultrasonic scalers were adapted for instrumentation aided by the endoscope. RESULTS: Endoscope technology has been successfully adapted for use in periodontal diagnosis and therapy. Techniques for identification and interpretation of the hard and soft tissue images, as well as the location of root deposits and caries, have been developed. CONCLUSIONS: The dental endoscope gives the clinician direct, real-time visualization and magnification of the subgingival tooth root surface, aiding in the location of deposits on the tooth root. The subgingival soft tissue, including the gingival attachment, sulcus wall, and sulcus contents, can be assessed. Identification and location of subgingival caries, root fractures, tooth root deposits, post perforations, and open restoration margins may aid the clinician in diagnosis and therapy.

Computer Terminals↗