Interesting to see this question here because I am reading Walter Borchenko's , Capture One Advanced Application Manual and he refers to the human eye model.
According to to Mr. Borchenko, the way the human eye captures light is with rods for color and cones for density, and that this two subsystems generate parallel data outputs that are combined at the end by our mind to visualize the external world.
He continues to explain that Phase uses a similar approach generating "2 sets of information" created from the original raw data. The streams of data are kept separated -- this it the vital element -- "The black data is saved as lightness data, and the color data is saved in a similar technology to chroma and hue information as found on the LAB color model."
Each data set can be adjusted independently.
The Manual also claims that:" In addition, the Phase One model of pixel building creates superior sharpness, color and range in highlights and shadows. this result is possible through superior quantities of color and density information even in highlights and shadows. Extreme lighting conditions also succeed with surprising hight quality"
... This Application Manual is not published by Phase one, but I know that Walter Borchenko makes content for Phase One, specifically, interviewing photographers that use the system to demonstrate the advantages compared to, say, Leaf, Hasselblad, Sinar, so, should we consider this book as an Phase One infommercial ?
But on the other side it is interesting to see the opinion of someone that works very close to Phase One and is willing to explain in detail the differences from one system to the other.