In previous studies, it was difficult to evaluate the productivity only by task performance. In this study, we tried to evaluate productivity not only by task performance but also by human reaction, which especially meant fatigue. Fatigue was measured by subjective votes and biological signal, which were human voice and flicker value. It is said that the Lyapunov index of human voice has possibility to evaluate fatigue. The experiment was conducted under the condition of 800lx and 3lx to examine the effect of light environment on productivity. Subjects were fourteen. As a result of the experiment, we could not find a significant difference on task performance of addition task between 3lx and 800lx conditions. On the other hand, the increasing rate of symptoms from subjective votes was significantly higher on 3lx conditions than on 800lx, and a standard deviation of Lyapunov index of “g”, “p” increased more under 3lx than 800lx. There were significant differences on fatigue in the experiment.
