The effect of color temperature of lighting sources on mental activity level.

The present study was designed to investigate the effects of color temperature of lighting sources on a contingent negative variation (CNV). Eleven male students (mean age, 23.2) volunteered as subjects. The CNV was recorded under three different color temperature conditions (3000 degrees K, 5000 degrees K and 7500 degrees K). The illuminance level was kept at 1000lx. The lighting condition caused no effect on the reaction time of the performance included in the CNV paradigm. On the other hand, the CNV was suggested to be influenced by the lighting condition. Especially, the CNV between 1025 msec to 1125 msec after the warning stimulus (S1) under 7500 degrees K was obviously larger than that under 3000 degrees K. This tendency was observed within the range between 800 msec and 1300 msec. Judging from no correlation between the light condition and reaction time, the concept of readiness potentials has little possibility for explaining the difference in CNV between the lighting conditions. Therefore, the difference in CNV between 3000 degrees K and 7500 degrees K was concluded to be originated from some differences in orienting response. The color temperature of 7500 degrees K was considered to be more activating than the color temperature of 3000 degrees K from the viewpoint of reticular activating system in CNV mechanism.