Perceivable Thresholds for Distinguishing Different CCTs: A Preliminary Study

The influence of correlated color temperature (CCT) on the color quality of light sources has been extensively investigated. However, the limitations and nonuniformity associated with the CCT parameter have hindered its effectiveness in lighting designs and applications. To explore the color perception and visual memory of light sources with varying CCT values, three preliminary experiments based on Signal Detection Theory (SDT) methods were conducted. The discrepancies between observers' subjective judgments and the actual CCT of the light source (ΔCCT), along with sensitivity (d') and decision criterion (c), were calculated and analyzed. The results revealed that observers' color memory for light sources with specific CCT values was not accurate and significantly influenced by the observed light source's color temperature. Furthermore, disparities between high CCT group and low CCT group were also observed. The perceptible thresholds for distinguishing different CCTs were determined by both absolute ΔCCT value as well as sensitivity measure. Methodology advice was provided for future lighting research and applications in which CCT parameter was applied.