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PubMed2001

Techniques for the production of point-light and fully illuminated video displays from identical recordings.

Illumination of only a few key points on a moving human body or face is enough to convey a compelling perception of human motion. A full understanding of the perception of biological motion from point-light displays requires accurate comparison with the perception of motion in normal, fully illuminated versions of the same images. Traditionally, these two types of stimuli (point-light and fully illuminated) have been filmed separately, allowing the introduction of uncontrolled variation across recordings. This is undesirable for accurate comparison of perceptual performance across the two types of display. This article describes simple techniques, using proprietary software, that allow production of point-light and fully illuminated video displays from identical recordings. These techniques are potentially useful for many studies of motion perception, by permitting precise comparison of perceptual performances across point-light displays and their fully illuminated counterparts with accuracy and comparative ease.

Computer Terminals↗
PubMed1999

Comparing visual perception on conventional cabinet tachistoscopes and computer monitor tachistoscopes.

Computer monitor-based tachistoscopes (using a cathode ray tube, CRT) and conventional tachistoscopes differ in experimental control over stimulus continuity, duration, and timing accuracy. This study evaluated the perception of visual stimuli presented with the two different types of devices. An experiment was conducted to compare recognition of visuospatial stimuli (random shapes) presented laterally and centrally in the visual fields for short exposure durations (14, 29, and 43 msec), first with one device and then with another. Results indicated that the subjects' error rates and laterality patterns were similar on both types of tachistoscopes. It was concluded that perception of visual stimuli presented as continuous images on a conventional tachistoscope may be equivalent to perception of visual stimuli presented as pulsating images on a CRT. Further studies are needed using other types of visual materials to determine the range of visual stimuli for which both types of tachistoscopes measure equivalent perceptual processes.

Adolescent↗
PubMed1989

Automation of learning-set testing: the video-task paradigm.

Researchers interested in studying discrimination learning in primates have typically utilized variations in the Wisconsin General Test Apparatus (WGTA). In the present experiment, a new testing apparatus for the study of primate learning is proposed. In the video-task paradigm, rhesus monkeys (Macaca mulatta) respond to computer-generated stimuli by manipulating a joystick. Using this apparatus, discrimination learning-set data for 2 monkeys were obtained. Performance on Trial 2 exceeded 80% within 200 discrimination learning problems. These data illustrate the utility of the video-task paradigm in comparative research. Additionally, the efficient learning and rich data that were characteristic of this study suggest several advantages of the present testing paradigm over traditional WGTA testing.

Animals↗
PubMed1998

Overuse tendinitis of the intrinsic muscles.

Repetitive strain injuries are currently the leading cause of occupational illnesses. This report describes seven patients who presented with the sole symptom of hand pain and subsequently were diagnosed with intrinsic tendinitis. Six of the 7 patients were given injections of a local anesthetic and steroid solution into the region of the lumbrical tunnels for both diagnostic and therapeutic purposes. All 6 patients had immediate short-term resolution of their symptoms in the office, thereby confirming the diagnosis. Complete resolution of symptoms after both the injection and other treatment interventions occurred in 4 patients, and partial resolution of symptoms occurred in the remaining two patients. Follow-up ranged from 3 to 20 months for 6 patients, and the seventh patient was lost to follow-up. The clinical presentation, diagnostic work-up, and treatment of intrinsic tendinitis are described.

Adult↗
PubMed1999

[Age-dependent changes in dynamic body balance as evaluated by the Body Tracking Test (BTT)].

Stability of Posture and gait decays with aging. In this study, we constructed the Body Tracking Test (BTT), to evaluate dynamic body balance function as opposed to static balance. Healthy volunteers of various ages (total, 272 persons) were subjects of the study. The principle of the BTT was for the subject to attempt to track an optical moving target displayed on a computer screen by shifting his or her body's center of gravity that was also displayed. The target moved for a span of 15 cm horizontally on the 14-inch screen, and also, in lateral and antero-posterior (horizontal and vertical) on CRT directions at a constant velocity of 0.125 Hz. Sixty-seconds recordings are obtained. In BTT, the gain for target against tracking was fixed at 2.0 (target:tracking = 1:2). The target was 100 cm anterior to the platform where the subject stood erect with the feet close together. The criteria for evaluation of the tracking function were determined by our preliminary study, titled "Index of BTT movement", and was useful during our present study. These criteria were determined ranking to E from A. The A rank indicated best tracking. Determination of rankings were performed by good or not tracking line against target trace line on recorded papers. Age-dependent changes in scores were obtained and analyzed. Results suggested that the tracking ability started to deteriorate after age 40, and these differences were observed in lateral and antero-posterior (horizontal and vertical on CRT) directions for all age groups. Tried for a with 30 years old changes, increase of a rate that A ranking occupies with a lateral direction law fast stimulation BTT from 20-year-old changes though, didn't try for a significant difference with a antero-posterior direction law fast stimulation BTT. Try start were 50-year-old changes with an antero-posterior BTT, 40-year-old changes with a lateral BTT E ranking. C, D, rate that E ranking occupies increases consequently to become 80-year-old changes and advanced age from 60 years on. For the tendency, a small tendency tried for the rate for antero-posterior stimulation BTT compared with a lateral stimulation BTT. Whether thought about for this, an of direction is prompt nearly against an outside stimulation since it keeps a balance with standing and being mended.

Adult↗
PubMed2006

Comparison of electrophysiologic monitors with clinical assessment of level of sedation.

OBJECTIVE: To assess the correlation between 2 clinical sedation scales and 2 electroencephalographic (EEG)-based monitors used during surgical procedures that required mild to moderate sedation. PATIENTS AND METHODS: Patients scheduled for elective surgery participated in this Institutional review board-approved study from March 2003 to February 2004. Level of sedation was determined both clinically using the Ramsay and the Observer's Assessment of Alertness/Sedation scales and with 2 EEG measures (the Bispectral Index version XP [BIS XP] or the Patient State Analyzer [PSA 4000]). Correlation between these 2 measures of sedation were tested using nonparametric statistical tests. RESULTS: The BIS XP monitor was used in 26 patients, and the PSA 4000 monitor was used in 24 patients. The Ramsay and Observer's Assessment of Alertness/Sedation scores correlated with each other (r = -0.96; P < .001) and with both the BIS XP (r = -0.89 and r = 0.91, respectively; P < .001) and the PSA 4000 (r = -0.80 and r = 0.80, respectively; P < .001) values. However, this correlation was strongest only at the extremes. Between the BIS XP and PSA 4000 values of 61 and 80, the clinical sedation scores varied greatly. CONCLUSION: On the basis of our results, these EEG-based monitors cannot reliably distinguish between light and deep sedation.

Computer Terminals↗
PubMed2002

[Interactive processes in video-mediated referential communication].

This study examined interactive processes that occurred in video-mediated referential communication task. Pairs of participants were assigned to one of four conditions; in a room with partition, or in separate rooms linked by telephone with three levels of noise interference (none, low, and high). In all conditions, a video-monitor link allowed the participants to see the upper body of their partner. Analyses of gestural and visual interaction revealed that participants in partition and no-interference conditions did not rely on the visual channel, while those in the others frequently looked at the monitor. Furthermore, gestural references appeared especially in high-noise condition. Qualitative analyses of conversations showed that participants in high-noise condition relied more on demonstrative references, and used more metaphoric expressions of a whole referent, based on the common ground shared by the pair. These results are discussed in terms of how people collaboratively interact and construct a shared context for communication between them.

Adult↗
PubMed1998

Computer mouse position as a determinant of posture, muscular load and perceived exertion.

OBJECTIVES: This study concerned the influence of 6 positions of the computer mouse on the work table on posture, muscular load, and perceived exertion during text editing. METHODS: An optoelectronic 3-dimensional motion analysis system was used to register the postures of 10 men and 10 women using video display units. Muscular load was also registered (with electromyography), as was perceived exertion (with rating scales). RESULTS: A neutral posture with a relaxed and supported arm showed the least perceived exertion, and the electromyographic results showed low activity in both trapezius muscles in this position. Short operators (all women) showed a numerically higher activity in the 4 examined muscles than the tall operators (all men, except 1). This finding could be related to lower muscle force among women and to anthropometric differences, which also influence biomechanic load moments. Narrow-shouldered operators (8 women and 1 man) and short operators worked with larger outward rotation and abduction of the shoulder in a position of the mouse lateral to the keyboard than the broad-shouldered (7 men and 2 women) and tall operators did. Arm support markedly reduced muscle load in the neck-shoulder region among the operators. CONCLUSIONS: The operators using video display units in this study preferred to use the mouse on a table in a close to relaxed, neutral posture of the arm in combination with arm support. Short and narrow-shouldered operators worked in more strenuous postures of the arm when the mouse was located lateral to the keyboard.

Adult↗
PubMed1999

Long-term effects on symptoms by reducing electric fields from visual display units.

OBJECTIVES: The purpose of the study was to see whether the results of an earlier study [ie, that skin symptoms were reduced by reducing electric fields from visual display units (VDU)] could be reproduced or not. In addition, an attempt was made to determine whether eye symptoms and symptoms from the nervous system could be reduced by reducing VDU electric fields. METHODS: The study was designed as a controlled double-blind intervention. The electric fields were reduced by using electric-conducting screen filters. Forty-two persons completed the study while working at their ordinary job, first 1 week with no filter, then 3 months with an inactive filter and then 3 months with an active filter (or in reverse order). The inactive filters were identical to the active ones, except that their ground cables were replaced by empty plastic insulation. The inactive filters did not reduce the fields from the VDU. The fields were significantly lower with active filters than with inactive filters. RESULTS: Most of the symptoms were statistically significantly less pronounced in the periods with the filters when compared with the period with no filter. This finding can be explained by visual effects and psychological effects. No statistically significant difference in symptom severeness was observed between the period with an inactive filter and the one with an active filter. CONCLUSIONS: The study does not support the hypothesis that skin, eye, or nervous system symptoms can be reduced by reducing VDU electric fields.

Adult↗
PubMed1995

Skin symptoms after the reduction of electric fields from visual display units.

OBJECTIVES: The objective of this work was to determine whether facial skin symptoms are reduced by decreasing static and low-frequency electric fields produced by visual display units. METHODS: The electric fields were reduced by electric-conducting screen filters. Twenty subjects took part in the study while working at their ordinary jobs, first two weeks without any filter, then two weeks with an inactive filter and two weeks with an active filter (or in reversed order). The inasctive filters were identical to the active ones except that the ground cable was cut. Measurements showed that the inactive filters reduced the static electric fields nonsignificantly less than the active filters. For extremely low-frequency fields the difference was greater, and the active filters reduced the very low-frequency fields significantly more than the inactive ones. RESULTS: Most symptoms were less pronounced with active filters than with inactive filters. The differences were small, and for one symptom only, tingling, pricking or itching, the result was statistically significant. The recorded physical and psychosocial factors did not explain the reduction with the use of active filters. Days with a long period spent near a visual display unit resulted in significantly more pronounced symptoms than days with short time. The findings registered by a dermatologist did not reveal any consistent difference between the two periods with filters. CONCLUSION: The results weakly support the hypothesis that skin symptoms can be reduced by a reduction of electric fields.

Adult↗
PubMed2000

Acute response to precision, time pressure and mental demand during simulated computer work.

OBJECTIVES: The electromyographic (EMG) activity of shoulder and forearm muscles was recorded during a standardized computer task with different combinations of time pressure, precision demands, and mental demands to study the interaction of these factors and their effect on muscular response during simulated computer work. METHODS: The computer task lasted 5 minutes, and it was performed by 14 female computer-aided design (CAD) operators during 8 exposure combinations that differed with respect to time pressure, precision demand, and mental demand. Performance (number of produced drawings, mouse clicks, and errors) were recorded. The EMG activity was recorded from the trapezius, infraspinatus, deltoid, and extensor digitorum muscles. An electrogoniometer was used to measure wrist postures and movements. RESULTS: High time pressure (combined with low precision and low mental demands) resulted in higher EMG activity for all the muscles and in a small increase in the number of produced drawings. High precision demands caused a large reduction in the number of produced drawings, but not always a change in EMG activity. High precision demands and high mental demands led to no change or a reduction in muscle activity because the number of drawings was greatly reduced. CONCLUSIONS: The interaction between work pace and other exposure factors must be taken into account when the effects of changes in exposure demands on muscular response are predicted. Only then can it be predicted whether changing demands will constitute a risk of developing musculoskeletal disorders.

Adult↗
PubMed2000

Differences between work methods and gender in computer mouse use.

OBJECTIVES: The aim of this study was to investigate whether gender or different methods of operating a computer mouse have an effect on performance and musculoskeletal load in the use of a computer mouse. METHODS: Thirty experienced computer mouse users, 15 men and 15 women, participated in the study. Electromyography (right first dorsal interossei, right extensor digitorum and right and left trapezius), a force-sensing mouse, and subjective ratings were used to register muscular load. An electrogoniometer was used to register the wrist movements. The subjects worked with 3 different methods, their own, a wrist-based method and an arm-based method. Gender comparisons were made when the subjects used their own method. RESULTS: The women worked with greater extension and range of motion and tended to work with a greater ulnar deviation of the wrist. They also applied higher forces to the mouse when expressed as a percentage of a maximum voluntary contraction and had higher muscular activity in the right extensor digitorum. When using the arm-based method, the subjects worked with greater wrist extension, had higher muscular activity in the right and left trapezius muscles, and had the highest ratings of perceived exertion in the neck and shoulder. The wrist-based method resulted in higher forces being applied to the sides of the mouse and the highest ratings of perceived exertion in the wrist and hand-fingers. CONCLUSIONS: Gender differences were found for musculoskeletal load, and for most of the measured variables the women worked with higher loads than the men. The work method affected performance and musculoskeletal load. Finally, subjective measures appeared to have some utility in characterizing muscular load.

Adolescent↗
PubMed2002

Effects of ergonomic intervention in work with video display units.

OBJECTIVES: This study evaluated the effect of an intensive ergonomic approach and education on workstation changes and musculoskeletal disorders among workers who used a video display unit (VDU). METHODS: A randomized controlled design was used. The subjects (N=124) were allocated into three groups (intensive ergonomics, ergonomic education, reference) using stratified random sampling. The evaluation involved questionnaires, a diary of discomfort, measurements of workload, and an ergonomic rating of the workstations. The assessments were made 2 weeks before the intervention and after 2 and 10 months of follow-up. RESULTS: The intensive and training groups showed less musculoskeletal discomfort than the reference group after 2 months of follow-up. Positive effects on discomfort were seen primarily for the shoulder, neck, and upper back areas. No significant differences were found for the strain levels or prevalence of pain. After the intervention the ergonomic level was distinctly higher in the intensive ergonomic group than in the education or reference group. CONCLUSIONS: Both the intensive ergonomics approach and education in ergonomics help reduce discomfort in VDU work. In attempts to improve the physical ergonomics of VDU workstations, the best result will be achieved with cooperative planning in which both workers and practitioners are actively involved.

Adult↗
PubMed2003

Effects of software programs stimulating regular breaks and exercises on work-related neck and upper-limb disorders.

OBJECTIVES: This study evaluated the effects on work-related neck and upper-limb disorders among computer workers stimulated (by a software program) to take regular breaks and perform physical exercises. Possible effects on sick leave and productivity were studied as well. A randomized controlled design was used with cluster randomization. Altogether 268 computer workers with complaints in the neck or an upper limb from 22 office locations were randomized into a control group, one intervention group stimulated to take extra breaks and one intervention group stimulated to perform exercises during the extra breaks during an 8-weekperiod. Questionnaires were administered before andafter the intervention, and questions were generated by the software during the intervention period. Computer usage was recorded online. RESULTS: The data on self-reported recovery suggested a favorable effect; more subjects in the intervention groups than in the control group reported recovery (55% versus 34%) from their complaints and fewer reported deterioration (4% versus 20%). However, a comparison between the reported pre- and postintervention scores on the severity and frequency of the complaints showed no significant differences in the change among the three groups. No effects on sick leave were observed. The subjects in the intervention groups showed higher productivity. CONCLUSIONS: The use of a software program stimulating workers to take regular breaks contributes to perceived recovery from neck or upper-limb complaints. There seems to be no additional effects from performing physical exercises during these breaks.

Analysis of Variance↗
PubMed2002

[Influence of electromagnetic waves on portable electronic instruments in medicine].

In this work, we considered the effect of electromagnetic compatibility (EMC) on electronic instruments used in medical facilities. We simulated and measured the intensity distribution of the electromagnetic field around portable phones and examined the influence of electromagnetic field on telemeter-type electrocardiograms (ECG) and computer display cathode ray tubes (CRT) when portable phones were brought close to them. Results showed that the waves observed on ECG are affected up to a distance of 55cm (3.55E+03V/m) from the portable phone, and the grid of the computer display is affected up to a distance of 9cm (7.16E+04V/m) in the front and 14cm (2.97E+04V/m) in the back. Therefore, to reduce electromagnetic intensity (EMI) maintaining a distance far enough from the source is effective.

Cell Phone↗