he purpose of this research is to confirm whether there is a difference in brightness sensations between genetically determined and acquired through experiences and, if there is, to explore a relationship between the brightness sensation acquired through experiences and individual lifestyles associated with luminous environment. Eight ordinary young people, from fourteen to twenty-three years old, were asked to participate in this experimental study. We interviewed them about their lifestyles, and asked them to measure their exposed illuminance while they are staying at home, and also asked them to be the subjects for two kinds of controlled experiments : thirty-second experiment and twenty-minute experiment. The brightness sensation obtained from the thirty-second experiment correlates with the ratio of illuminance at voting to the illuminance ten seconds before voting, while that obtained from the twenty-minute experiment correlates with the illuminance averaged for the thirty seconds before voting. These results suggest that there is a difference in brightness sensations between genetically determined and acquired through experiences. We could sort out eight subjects into three groups using the results of interview and measurement of exposed illuminance at home. 0ne is for those using daylight available from windows, another is using electric light whether or not there is daylight, and the last is using both daylight and electric light. There are quite a few cases ifi which some subjects vote that it is bright enough but at the same time they want to open the shade or that it is a little dark but they want the lighting condition to remain unchanged. Those subjects belonged consistently to one of the groups, daylighting group. The same is true for another group, electric lighting group. We thus confirmed that there is a difference in brightness sensations between genetically determined and acquired through experiences.
