Comment by ramonaisonline

The boundary regions at 3:00, 7:00, and 11:00 are composite colors that have ~2x the brightness compared to the primary colors of red, green, and blue. For someone without a color vision deficiency, they appear brighter than surrounding colors, but the saturation really only varies with distance from the center. For example, to me, the point at 3:00 on the edge of the circle is the peak of a "ridge" in brightness, but appears as a very saturated teal.

I have a colorblindness simulator on my computer called Sim Daltonism and when I use that on the color wheel, it does indeed appear to have white, desaturated lines radiating from the center at those three angles. In the simulator, the one at 11:00 is the strongest, followed by 3:00, and the 7:00 one is faintest. My hunch is that the perceptually uniform color space samples you're looking at have more uniform brightness, so those boundaries blend in to the surrounding colors better. They look nicer to me too -- they still represent saturated, composite colors like teal, but just at a pleasant, harmonious brightness. It's very interesting to compare perception!