Colour discrimination evaluation under multiple light sources using signal detection theory.

Colour discrimination is a crucial research topic in lighting quality studies. Till now, various experimental methods have been widely adopted. Those methods based on the traditional colour-discrimination framework primarily focused on observers' ability to perceive discernible colour differences while neglecting the impact of noise and the corresponding possibility of false alarms. In this study, signal detection theory (SDT) was introduced to enhance the rationality of the experimental design and data analysis of the current methodology. The effects of various contextual factors on colour discrimination were systematically investigated under multiple light sources by three groups of psychophysical experiments. The results indicated that compared to traditional methods, the SDT framework largely incorporated previous findings and revealed new discoveries. Separating the colour discrimination process into sensory sensitivity and decision-making criteria provides a deeper explanation for the human colour discrimination performance under various experimental conditions. Additionally, by controlling the experimental set-ups, we demonstrated that the effect of lighting on observers' sensitivity and decision criterion could be manipulated. These findings provide strong evidence for the advantages of the SDT framework when investigating the colour discrimination process.