Effect of Illuminance and Light Strobe on Attention and Visual Fatigue in Indoor Lighting

Abstract

For indoor lighting, illuminance is one of the important factors which can indicate the quality of lighting condition. However, with the popularity of LEDs, temporal light artefacts (TLA) caused by LED drivers or PWM technique has also become another consideration for evaluating the indoor lighting. One major factor that affects TLA is the frequency of light strobe. Even frequency is too high to be perceived, it will also have a negative impact on people’s attention and visual perception to a certain extent. Previous studies seldom studied the combination effect of illuminance and frequency. Therefore, this study combined these two factors to investigate the change of various indicators that reflect people’s attention and visual fatigue under different indoor lighting conditions. Three illuminance levels, 50lx, 150lx and 500lx and three frequency levels, 100Hz, 300Hz and 1000Hz were analyzed. A within-subject design was adopted. Twelve healthy students participated in the experiment. Subjective evaluation scales and the D2 task were used as the experimental methods. Factor analysis and MANOVAs were used for the data analysis. It was found out that illuminance significantly affected subjects’ attention and alertness (p<0.05). Meanwhile, visual fatigue such as ghosting and blurring mainly caused by frequency was affected by illuminance (p = 0.038<0.05), which proved our hypothesis.