Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Computer Terminals”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 901 records · Page 50Linked to original sources
PubMed2005

Surface exploration using laparoscopic surgical instruments: the perception of surface roughness.

During laparoscopic surgery video images are used to guide the movements of the hand and instruments, and objects in the operating field often obscure these images. Thus, surgeons often rely heavily on tactile information (sense of touch) to help guide their movements. It is important to understand how tactile perception is affected when using laparoscopic instruments, since many surgical judgements are based on how a tissue 'feels' to the surgeon, particularly in situations where visual inputs are degraded. Twelve naïve participants used either their index finger or a laparoscopic instrument to explore sandpaper surfaces of various grits (60, 100, 150 and 220). These movements were generated with either vision or no vision. Participants were asked to estimate the roughness of the surfaces they explored. The normal and tangential forces of either the finger or instrument on the sandpaper surfaces were measured. Results showed that participants were able to judge the roughness of the sandpaper surfaces when using both the finger and the instrument. However, post hoc comparisons showed that perceptual judgements of surface texture were altered in the no vision condition compared to the vision condition. This was also the case when using the instrument, compared to the judgements provided when exploring with the finger. This highlights the importance of the completeness of the video images during laparoscopic surgery. More normal and tangential force was used when exploring the surfaces with the finger as opposed to the instrument. This was probably an attempt to increase the contact area of the fingertip to maximize tactile input. With the instrument, texture was probably sensed through vibrations of the instrument in the hand. Applications of the findings lie in the field of laparoscopic surgery simulation techniques and tactile perception.

Adult↗
PubMed2005

Visual effects of the luminance surrounding a computer display.

The luminance surrounding a computer display can potentially reduce visibility of the display (disability glare), result in sensations of discomfort (discomfort glare) and result in transient adaptation effects from fixating back and forth between the two luminance levels. The study objective was to measure the effects of surround luminance levels upon these functions in younger and older adults to determine recommended surround luminance levels. The younger age group comprised 20 subjects (mean age 27.9 years, range 23 - 39) and the older group 17 subjects (mean age 55.5 years, range 47 - 63). The central task was presented with luminance of 91 cd/M(2), tested surround luminance levels were 1.4, 2.4, 8.9, 25.5, 50, 91, 175, 317, and 600 cd/M(2). Disability glare was tested with low contrast (20%) visual acuity charts, transient adaptation was tested with a task that required regular fixation between the two luminance levels, discomfort was measured with a questionnaire after reading stories with different surround luminance levels, and preferred luminance was measured by method of adjustment. The surround luminance significantly affected transient adaptation (p < 0.0001), optimal performance occurred at 50 cd/M(2) and above for the young group and at 91 cd/M(2) and above for the older group. Neither low contrast acuity (disability glare) nor symptoms when reading were significantly affected by surround luminance. There was wide variation in preferred surround luminance; however, average preferred surround luminance was 86.9 cd/M(2) for the young group and 62.2 cd/M(2) for the older group, slightly below the central luminance of 91 cd/M(2). The effects of the surround luminance within the tested range are not large; however, the data show that the lowest surround luminance levels should be avoided and that surround luminance levels at or slightly below that of the central task are preferred.

Adaptation, Physiological↗
PubMed2006

The feasibility of repositioning ability as a tool for ergonomic evaluation: effects of chair back inclination and fatigue on head repositioning.

Poor posture has been suggested as one of the main factors contributing to the high prevalence of neck pain in video display unit (VDU) users, but no clear association between pain and any particular resting neck posture has been found. Postural awareness of the neck, as indicated by the repositioning accuracy, may therefore be an appropriate measure and potentially useful assessment tool. The objective of this study is to examine whether posture and fatigue affect the head repositioning ability in typical VDU usage. A group of 20 healthy participants reproduced a normal comfortable posture for forward, upright and backward chair back inclinations in random order both before and after fatigue of the upper trapezius muscles. Ten repetitions of the posture were recorded for 2 s each, and the angular and translational deviations from the original head position were measured with regard to the external environment (head in space repositioning) and with regard to the trunk (head on trunk repositioning). Analysis by repeated measures ANOVA showed significant effects and interactions of fatigue and chair back inclination on the repositioning errors in the sagittal plane, which typically showed systematic trends towards certain postures rather than random errors around a mean position. While further work is required to examine the ergonomic impact of impaired repositioning ability, head repositioning is sensitive to ergonomic factors such as seating configuration and fatigue, and may therefore be a useful tool for evaluation of static working postures.

Adult↗
PubMed1990

Change in visual function and viewing distance during work with VDTs.

Seven female volunteer bank clerks aged between 24 and 32 yr were selected for a laboratory trial after a preliminary ocular examination which showed them to be emmetropic or slightly myopic (less than or equal to 1D) and to have normal ocular motility or only minor deficiencies. Near and far point refraction and phorias and near point fusional vergences were measured before and immediately after a 6 h workday at a PC workstation. Eye screen distance (viewing distance) was monitored. Near and far distance refraction showed an increase and a decrease of accommodation in 13 out of 14 eyes respectively. Fusional convergence decreased in six out of seven cases: a smaller decrease in divergence was recorded in all subjects. These changes were statistically significant. Viewing distance, though showing some interindividual differences, increased considerably during the last 2 h of the trial, without reaching statistical significance.

Adult↗
PubMed1990

CRT display visibility in automobiles.

Three experiments were carried out into aspects of CRT display in the context of driving automobiles. The first focused on the combination of colours which renders information 'easy-to-read', and determined the relationship between luminance contrast and chromaticity difference. In the second a background luminance which was not dazzling at night was expressed in a chromaticity diagram. In the third the amount of information which can be read 'at-a-glance' was investigated.

Automobiles↗
PubMed1990

The ergonomic evaluation of eye movement and mental workload in aircraft pilots.

This paper presents an experiment which examines characteristics of pilots' scanning behaviour when using integrated CRT displays, and the changes in characteristics when pilots face abnormal situations. The subjects were five experienced pilots. They performed two modes of flight tasks, under normal and abnormal situations, in flight simulators with standard settings. The flight simulators were for a Boeing 747-300 (B747), which made use of electromechanical displays, and for a Boeing 767 (B767), equipped with integrated CRT displays. The results showed that the B767 pilots tended to gaze at the attitude director indicator which was displayed in the integrated CRT display. It was assumed that 'gaze-type scanning' might be one of the characteristics of pilots' scanning behaviour in cockpits which use the integrated display. By employing subjective ratings and heart rate variability to measure mental workload, no differences in mental workload between the B767 pilots and the B747 pilots were observed. However, in abnormal situations, the changes in scanning pattern for B767 pilots were found to be smaller than those of the B747 pilots. It is concluded that the application of integrated displays helps pilots to obtain sufficient information more easily than electromechanical displays do, even under abnormal situations.

Adult↗
PubMed1990

Examination of the near triad in VDU operators.

It has recently been demonstrated that the tonic level of accommodation is related to the loading of accommodative work. The aim of the present study was to investigate the effect of a sustained accommodative stimulus on the tonic level of accommodation, pupil, and convergence, i.e., the near triad, in three different groups of young (20-39 years) subjects, viz., 1. 19 professional visual display unit (VDU) workers; 2. 12 ordinary hard copy (non-VDU) workers; and 3. 19 control subjects doing different jobs from the two former groups. All had worked 25-30 h per week for over two years. Only Groups 1 and 2 had eyestrain after office work. Except for mild myopia, subjects had no eye or systemic disease upon routine examination. Accommodation was measured with an objective infrared optometer, the pupil was measured by an infrared video pupillography, and convergence was measured from the contralateral eye by photoelectronic oculography. In order to elicit tonic responses, the velocity of the target stimulus was 0.2 D (diopters) per second. Based on the data obtained from the controls, the near triad was analysed. Asymmetric response of the near triad in the right and the left eye and the existence of a hysteresis curve, especially in the pupil and in convergence, were the major findings. No abnormality was found in the control group. In the VDU group, 34.6% showed an abnormal near triad, but this also occurred in 18.5% of the non-VDU group. Even with the same complaint of eyestrain, it was concluded that VDU work produced abnormalities 1.8 times higher in the near triad produced by tonic stimulus.

Accommodation, Ocular↗
PubMed1990

An ergonomic evaluation of lens accommodation related to visual circumstances.

This study is intended to make clear the relationships between a number of external conditions (target luminance, size, etc.), dynamic responsiveness of the lens accommodation, and microfluctuation. Further, the effects of ageing and the difference between monocular and binocular observations are examined. These studies established that age factors have a large bearing on the ability of the lens to focus on an object, as well as affecting such abilities as the responsiveness of the lens accommodation, amplitude of lens accommodation response, microfluctuation, and contraction and relaxation time. Of these accommodation functions, such factors as contraction and relaxation time clearly reflect the ease of seeing an object. Clear relationships between the amount of diopter and the ease of seeing an object were also observed. Further, it was established that a binocular observation is more responsive (velocity of contraction) than a monocular one. As to the microfluctuation, on the other hand, clear effects of age on its spectrum distribution were recognized but no definite correlations concerning the ease of seeing an object were observed.

Accommodation, Ocular↗
PubMed1991

Shoulder muscle tension induced by two VDU-based tasks of different complexity.

This paper evaluates task complexity as a task-related factor causing the development of psychologically mediated ('psychogenic') shoulder muscle tension. Eighteen subjects performed an experimental work session, responding to simple and complex reaction time tasks which were presented on a VDU screen. Most subjects generated low-level static muscle tension during the tests. On a group level the two tasks did not have a differential effect on muscle tension. However, a subgroup of eight subjects which consistently generated higher muscle tension in the complex tests, was identified. It is argued that for these subjects the difference in muscle tension is due to an increased mental effort invested, because of the higher computational demands in the complex task.

Adult↗
PubMedDate not supplied

A method of evaluating VDT screen layout by eye movement analysis.

The method for evaluating VDT screen layout by eye movements is studied. When the subjects read from the VDT screen, the change in their line of sight was measured by their eye movements. The measured eye movement patterns were divided into the sequential and rereading processes. When related to these characteristics, the performance of subjects was found to be good when the sequential process predominated over the rereading process. The eye movement pattern was shown to change with screen layout. The eye movement pattern proved effective in determining that tabular format is more legible than textual format. This confirmed the usefulness of the method of evaluating VDT screen layout by the eye movement pattern.

Attention↗
PubMedDate not supplied

Does fatigue exist in a quantitative measurement of eye movements?

The measurement system for quantitative analysis of eye movements and distribution of eye fixation points was developed through the study. Experiments on physiological fatigue characteristics of eye movements were studied using the system. The subjects involved in the study were six young males. No significant change was quantitatively found in saccadic eye movements during and/or after five hours of rapid eye tracking tasks. The saccadic velocity of two subjects were found in binocular decreased temporarily. The maximum velocity of eye movements obtained in the present experiment was ascertained in order to produce a scale for various visual work as an ergonomic index.

Asthenopia↗
PubMedDate not supplied

Visual capability to receive character information. Part I: How many characters can we recognize at a glance?

A study was made on the capability to receive character information and the factors restricting it. The study showed that the capability indicated by the memory span was limited by the average number of characters for words that are made up of individual characters, and calculated in terms of information quantity, there was no difference among the individual characters. The differences in memory span, depending on the size of the pattern presented, was negligible. The difference in the way characters were arranged produced the difference in memory span saturation. This phenomenon is explained by the nature of the lateral interference effect working among the adjacent characters.

Attention↗
PubMedDate not supplied

Visual capability to receive character information. Part II: How long do we need to memorize the random characters briefly presented?

The time-related aspect of the capability to receive character information was measured and analysed. As a result, when the presentation time was shorter than one second, ability was almost constant, but when it exceeded one second it increased as the presentation time increased. It was found that when a pattern was presented without limiting the presentation time, there were linear relationships between the number of characters to be memorized and the time required to memorize all the characters correctly in the range of 2 to 6 characters, 7 to 12 and 13 to 16 (or more). These boundaries corresponded well to a unit of memory well known as the magical number 7 plus minus 2. From these results, it was estimated that a grouping mechanism exists even when memorizing characters and that it has a hierarchical structure.

Attention↗
PubMedDate not supplied

Basic study on the measuring of fatigue by the minimum audible pressure.

Nowadays, human senses of vision and hearing receive many stimulations. In particular, VDT work is commonly performed by people of all ages. Therefore, in order to regulate working hours we need to measure the fatigue due to VDT work. The current measuring system depends on the flicker value (CFF). This report describes a new measuring system which depends on the measurement of the fluctuation in the minimum audible pressure (MAP) while using the increase of threshold value as an index of fatigue, and the results of the related experiment. In Test 1, the test sound was set at the pure sound of 1,000 Hz. In Test 2, an ordinary hearing acuity inspection room was used, using the method of limit measurement and headphones (Telephonics, TDH39, MX41/AR). As a result, it was verified that the most suitable rate of increasing and decreasing audible pressure was by 2 dB or 1 dB. It was proved from these tests that the minimum audible pressure could be used satisfactorily as a practical index for absolute measurement of hearing sense fatigue.

Auditory Threshold↗
PubMed1993

Menstrual cycle effects on a VDT-based simulation task: cognitive indices and subjective ratings.

It is unclear whether the menstrual cycle affects the basics of performance, mainly task performance and cognitive functions. We examined menstrual cycle effects on VDT-based task performance, cognitive indices based on the signal-detection theory, and subjective ratings in questionnaires. We experimented in three phases: premenstrual, menstrual and postmenstrual phases. Previous studies reported premenstrual tension syndrome (PMST) in the premenstrual phase. Women used physiological and psychological strategies to cope during the menstrual phase. However, task performance, cognitive indices and subjective ratings showed no menstrual cycle effects. Thus, we can conclude that the information processing for the VDT-based task was not affected by menstrual cycle.

Adult↗
PubMed1994

The effect of motivation on shoulder-muscle tension in attention-demanding tasks.

This paper evaluates motivation as a task-related factor causing the development of psychologically mediated ('psychogenic') shoulder-muscle tension. In four separate experiments using a visual display unit (VDU) based complex reaction-time task, motivation was established by means of continuous feedback on the level of performance (relative to a preset target performance level) or by means of a money reward for good performance. In all experiments motivation improved the performance, but an increase in the psychogenic shoulder-muscle tension was only observed in the money-reward condition. It is discussed whether this difference in the muscle-tension response is due to changes in the subjects' attitude unrelated to performance or due to a superior performance in the money-reward condition.

Adult↗
PubMed1994

Ageing, computer-based task performance, and stress: issues and challenges.

An emerging problem that encompasses both traditional ergonomic as well as macroergonomic concerns involves assessing the potential implications of computer-based tasks for older workers. An increasing older workforce and the influx of computer technology into a wide variety of work settings has motivated both a re-examination of the literature concerning ageing and work performance and research that more directly addresses the computer-interactive task domain. In this paper, we overview this literature and raise a number of crucial issues concerning potential age differences in performance and stress associated with computer-based tasks. Underlying our discussion throughout is the intention of identifying the challenges that await interested practitioners and researchers.

Adult↗