Since blue does not contribute to brightness, this creates fuzzy edges. Ask them to note which colors are easy to read and which are difficult. They should notice that dark blue signs are difficult to read at night - for example, the Qualcomm sign is a dark blue and is very difficult to read at night. It is also very difficult to read dark blue text on a black background. Older operators need higher brightness levels to distinguish colors.
Colors change in appearance as the ambient light level changes.
The magnitude of a detectable change in color varies across the spectrum. It is difficult to focus upon edges created by color alone. Avoid red and green in the periphery of large displays. Opponent colors go well together. Physics of color, color vision, color models, color perception.