During the test, the illumination levels were increased within a wide range from 100 to 750 lx. It
was expected that the participants would perform best based on their individual abilities under
these lighting conditions. Hence, it is expected that the participants would record their minimum
number of errors under the most preferred illumination level. The number of errors made under
different illumination levels were analysed considering the percentage errors made and their mean
values for varying illumination levels.