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Large screens have become more popular in recent years. Because of the increasing size of displays, the amount of information presented in the peripheral visual field has gained importance in many tasks on visual display units. Users of displays are often exposed to some change or difference in luminance in or between different areas of a display, which in turn may produce a phenomenon known as discomfort glare. Discomfort glare is likely to affect cognitive performance. The performance in the visual periphery is more susceptible to disturbances as is the case for the performance in the central visual field. This study explored the effects of discomfort glare on detecting and processing peripheral visual information in a complex visual task. The task consisted of comparing the orientation of arrows presented in the central visual field and at 18° in the periphery. The arrows were superimposed on a background video and presented by a projection system in virtual reality. 50% of the presentations were preceded by a mild glare scene with a luminance of 25 cd/m2 flashed prior to the stimulus. Experimental results of 56 participants were analyzed using the theory of signal detection. A significant difference (two-tailed t-test p = 0.01) in detectability of stimuli (d′glare = 1.87; d′no glare = 2.11; Δd′ = 0.24) was obtained when comparing the performance in the two situations of glare. Results show that discomfort glare impairs peripheral visual performance in attending stimuli in a virtual reality environment. We therefore propose to consider discomfort glare as a factor affecting performance in detecting peripheral visual information. Discomfort glare should be included as a quality criterion in rating visual information, as is done in present standards of displays and lighting.

In a typical environment for augmented reality, subjects were asked to detect visual information presented at 15–28° in the periphery of the visual field. Information was displayed tachistoscopically for 200, 300 and 600 ms. Popular low cost beamer producing colour breakup was used to present peripheral stimuli. We found that exposure time affects detectability of targets. By extrapolating our results we compute that for a 100% correct detection the stimulus must be displayed for at least 2 s. Age does not affect detectability.

In an explorative task subjects were asked to track a line presented in combination with other confusing lines on a 3D display. 24 subjects performed the explorative task under three depth cue conditions which were: stereopsis, movement parallax or a combination of stereopsis and movement parallax (stereo and parallax). Task performance was assessed by recording completion time and correctness of answer. The combination of stereopsis and movement parallax gave rise to highest percentage of correct answers (84%), followed by the condition where movement parallax was the only depth cue (80%). Percentage of correct answers in both conditions was found to be significantly higher than it was in the condition with stereopsis (60%). Mean completion time was about the same in the stereo and parallax condition and the stereopsis condition. Compared to the movement parallax condition both means were significantly decreased. Accuracy in completing the task was found to be similar in 3D displays enabling movement parallax and in 3D displays presenting stereoscopic images.

Two experiments were carried out in this study. The first experiment assessed a subject's performance while carrying out a visual search task using a liquid crystal display (LCD) and a cathode ray tube (CRT) with varying refresh rate (48–75 Hz). The subject's task consisted of detecting a target character among distractor characters presented in positive contrast. Search time was similar in all conditions of the experiment. Error frequency was correlated positively with the refresh rate of the CRT. However, this effect failed to be significant (p=0.090). In the condition where LCD was used, error frequency was found to be 22% lower when compared to the condition where the CRT was used with a refresh rate of 75 Hz. A second experiment aimed to assess the role of background luminance in the same task as reported above. The task was carried out on the liquid crystal LCD. The background luminance was varied between 45 and 150 cd/m2 at the LCD and between 45 and 110 cd/m2 at the CRT. Results of this experiment revealed no statistical significant effect of background luminance on visual performance (number of hits, search time). These findings suggest that replacing CRTs with LCDs will improve ergonomics in workplaces using visual displays. Improvements can also be achieved by increasing the refresh rate of the CRT but a very high refresh rate may be required.

Aim : In this study a computer-based approach using random-dot stereograms (RDS) to assess stereopsis is presented for screening applications. Method : The TNO-test is a common method to assess stereopsis using anaglyphic RDS. This technique was transferred to computer-based use. The efficiency of the computer-based approach was analysed by testing 25 subjects for stereopsis using the computer-based approach and the TNO-test. Results : The generation of RDS did not allow an exact separation when using colour filters, regarding the spectral emission of the monitor. An adjustment of the RDS colours to the available colour filters and the spectral emission of the monitor allowed a sufficient separation. The resolution of the monitor required a viewing distance of 2 m. The results from testing the subjects did not produce a significant difference between the methods. Conclusions : A computer-based assessment of stereopsis could use analgyphic methods. The influence of the spectral emission of a monitor with cathode ray tubes and its resolution can be ignored after an optimisation of the colours to generate the RDS and an increased viewing distance for the computer-based use.

Cathode ray tube (CRT) display and liquid crystal display (LCD) were compared for their suitability in visual tasks. For this purpose visual performance was assessed by means of a search task carried out using both displays with different levels of ambient light. In addition, suitability was rated subjectively by users of visual display units (VDUs). Error frequency for search tasks carried out using LCD were significantly smaller when compared to error frequency for tasks at CRT. LCD gave rise to 34% less errors than did CRT. Reaction time in search task was found to be significantly shorter using LCD when tasks were carried out in darkness. Subjective rated suitability of LCD was scored twice as high as suitability of CRT. Results indicate that LCD used in this experiment may give better viewing conditions in comparison to CRT display.

Aim: A commonly used method to examine the ability of the visual system to discriminate colours is based on isochromatic plates, such as the Ishihara plates. This article will introduce a computer-based method to determine red–green colour deficiencies based on presenting Ishihara plates using a CRT monitor. Method: The spectral emission of the reflected daylight of the plates was compared with the spectral emission of the plates presented on a CTR monitor. The screening efficiency of the Ishihara plates was assessed by testing 10 subjects with normal and 10 subjects with abnormal colour vision, using the Ishihara plates and using the computer-based approach. Results: It was experimentally shown that despite the differences between the spectral emission of the CRT monitor and the reflected daylight of the Ishihara plates, the computer-based method discriminates subjects with colour deficiencies from subjects without colour deficiencies. Conclusions: Using a CRT monitor for screening purposes, a reduced number of Ishihara plates is recommended to assess colour vision. The suggested method uses nine instead of 15 plates and a criteria of two not correctly detected plates to determine colour deficiency.

Accurate space perception within 3D display systems could be dependent on the real observer's viewpoint relative to the displayed 3D space. In this article, a stereoscopic display system is presented, which achieves viewpoint-dependent graphical simulation of space in real time. The concept, function and construction of the equipment is outlined. Emphasis is placed on the method used to measure the observer's viewpoint. The performance of the display system with respect to the capabilities of the human visual system is discussed and finally, a brief description of an experiment to quantify observer performance is given.