Environmental Engineering Reference
In-Depth Information
3.6 Effect of resolution of display type to visual symptoms
Table 6 shows the result of experiment on the effect of display resolution on the subjects.
Three level of resolution were investigated for both the liquid crystal display (LCD) and
cathode ray tube (CRT) displays, which are high resolution, medium resolution and low
resolution. The result of statistical binomial test at 5% significant level found that the overall
level of resolution using either the LCD or CRT displays causes eyestrain symptoms to the
users with more than 56% experiencing eyestrain. Others effect such as dry and irritated
eyes symptoms were experienced by 56% of users when interacting with medium and low
resolution CRT display.
3.7 Effect of contrast ratio
The result on the effect of contrast ratio to visual symptoms is described in Table 7. There
are three kind of contrast ratio investigated. They are -50.83%, +24.58% and 0%. The ratio
can vary from 100% (positive) to zero for targets darker than the background, and from zero
to minus infinity (-∞) for targets brighter than the background (Grether and Baker, 1972).
Statistical binomial test at 5% significant level shows that all contrast ratios causes eyestrain
symptoms (75% of users). Blurred vision and dry and irritated eyes symptoms were
experienced by 63% and 50% of users at contrast ratios of --50.83% and 0% (or -0.56%)
respectively.
Exact Sig.
(1-tailed)
Ratio of
Contrast
Observation
Proportion (%)
No.
Symptoms
Decision
75
63
Eyestrain
Blurred Vision
0.633
0.321
Effect
Effect
1.
-50.83%
2.
+24.58%
75
Eyestrain
0.633
Effect
75
50
Eyestrain
Dry and Irritated Eyes
0.633
0.114
Effect
Effect
3.
0% (-0.56%)
p
> 0.05 ; N = 8
Table 7. Result of Experiment and Binomial Test of Visual Symptoms of Contrast Ratio
4. Discussion
One of the parameters of cyber sickness is visual symptoms (Barret, 2004). In his handbook,
Anshel, J. (2005) mentioned that visual symptoms can vary but these mostly include
eyestrain, headache, blurred vision, dry and irritated eyes, double vision, colour distortion
and light sensitivity. The symptom most often occurs when the viewing demand of the task
exceeds the visual abilities of the user. The viewing task is influenced by the design of the
virtual environment viewed or interacted. This research has identified some attributes or
variables of the VE that may cause the occurrence of visual symptoms.
4.1 Analysis of the colour types for the virtual background design
Statistical binomial test on five types of colour of virtual background (Table 1) shows that
the colour type inflicts the users with eyestrain and blurred vision symptoms. Fig. 2 (a) and
