I did a custom combination of yellow outer field, blue inner circle, and got a vibrant purple halo, which is not what I expected. I assumed it would be "yellow++", based on what I know about the human eye's colour sensitivity.
I didn't expect a strong effect, because the overlap between blue and red/green is so much less than the overlap between red and green, but bright purple is close to the opposite of what I expected. I'm genuinely puzzled.
That is interesting - I tried the setup you suggested and actually did see something that could be described as yellow++, with maybe a hint of gold/orange
It was also very intense, like staring into the sun. I observed this for both of the two default yellow tints that I could choose via the (Windows?) color picker
I have no idea why this would differ between individuals
I retried it first thing in the morning, in the dark, with my phone screen at minimum brightness, and no contact lenses in, and I got the expected result - vivid gold for my original setting, vivid yellow for yours.
After putting my contacts in, under medium ambient light, with my phone screen at medium or full brightness, I get the purple ring, but now that I'm looking for it, I can see an outer ring of gold or yellow as well.
The effects is much less pronounced if I put on my reading glasses (while still wearing contacts), so I think it must be an artifact of the contact lenses, probably in combination with the conditions they're supposed to correct (nearsightedness + astigmatism), as well as age-related inability to focus on tiny details with my contacts in.
I didn't expect a strong effect, because the overlap between blue and red/green is so much less than the overlap between red and green, but bright purple is close to the opposite of what I expected. I'm genuinely puzzled.