Psychological Determinants of Brightness of a Space

Which lighting attributes determine the brightness of a room space? We considered the perceived strength of the light source and the perceived amount of light in the space as potential determinants. We examined the relations between the actual brightness of the space and these two perceptions. In the first experiment, subjects evaluated the strength of the light source and the amount of light in the space using reference matching method. The results were consistent among the subjects, indicating they judged each of the two lighting attributes by some common criteria. In the second experiment, the brightness of the space, the strength of the light source, and the amount of light in the space of a model box were evaluated using the magnitude estimation method under various illumination conditions. We found that the brightness of the space was closely correlated with the perceived amount of light but not with the perceived strength of the light source. These results should prove useful in constructing a model for quantitatively estimating the brightness of a space.